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Watershed Modeling System

WMS v8.4

TUTORIALS – Volume 1

BASIC DATA OPERATIONS

WMS 8.4 Tutorials – Volume 1

Copyright © 2010 Aquaveo, LLC

All Rights Reserved

Unauthorized duplication of the WMS software or documentation is strictly prohibited.

AQUAVEO LLC MAKES NO WARRANTIES EITHER EXPRESS OR IMPLIED REGARDING THE PROGRAM WMS AND ITS FITNESS FOR ANY PARTICULAR PURPOSE OR THE VALIDITY OF THE INFORMATION CONTAINED IN THIS USER'S MANUAL

The software WMS is a product of the Aquaveo, LLC. For more information about this software and related products, contact Aquaveo at:

Aquaveo 75 South 200 East, Suite 201 Provo, Utah 84606 Tel.: (801) 691-5528 e-mail: [email protected] WWW: http://www.aquaveo.com/

For technical support, contact Aquaveo’s tech support number at (801) 691-5530 (Monday-Friday, 8am-5pm Mountain Time)

TABLE OF CONTENTS

1 INTRODUCTION ................................................................................................................................... 1-1 1.1 EXERCISE FILES ................................................................................................................................. 1-1 1.2 STARTING OVER ................................................................................................................................ 1-1 1.3 GETTING AROUND THE WMS INTERFACE .......................................................................................... 1-2

2 IMAGES ................................................................................................................................................... 2-1 2.1 OBJECTIVES ....................................................................................................................................... 2-1 2.2 GEOTIFF FILES ................................................................................................................................... 2-2 2.3 WORLD FILES .................................................................................................................................... 2-3 2.4 IMAGE RESOLUTION ........................................................................................................................... 2-4 2.5 BUILDING PYRAMIDS ......................................................................................................................... 2-5 2.6 REGISTERING SCANNED IMAGES ........................................................................................................ 2-6 2.7 INTERNET EXERCISES ....................................................................................................................... 2-10 2.8 CONCLUSION .................................................................................................................................... 2-13

3 BASIC FEATURE OBJECTS ................................................................................................................ 3-1 3.1 OBJECTIVES ....................................................................................................................................... 3-1 3.2 CREATING AND EDITING FEATURE OBJECTS ...................................................................................... 3-2 3.3 USING SHAPEFILES TO CREATE FEATURE OBJECTS ............................................................................ 3-6 3.4 CREATING FEATURE OBJECTS USING BACKGROUND IMAGES ............................................................ 3-8 3.5 MORE FEATURE OBJECTS FROM IMAGES ......................................................................................... 3-11 3.6 DISPLAY OPTIONS ............................................................................................................................ 3-11 3.7 CONCLUSION .................................................................................................................................... 3-12

4 DEM BASICS ........................................................................................................................................... 4-1 4.1 OBJECTIVES ....................................................................................................................................... 4-1 4.2 GETTING DEMS FROM THE INTERNET ................................................................................................ 4-2 4.3 MERGING DEMS ................................................................................................................................ 4-6 4.4 TRIMMING DEMS .............................................................................................................................. 4-6 4.5 DISPLAYING DEMS ............................................................................................................................ 4-7 4.6 CONCLUSION ...................................................................................................................................... 4-9

5 USING TRIANGULATED IRREGULAR NETWORKS ................................................................... 5-1 5.1 OBJECTIVES ....................................................................................................................................... 5-1 5.2 IMPORTING SURVEY DATA ................................................................................................................. 5-2 5.3 GETTING A BACKGROUND IMAGE ...................................................................................................... 5-3 5.4 DIGITIZING DATA ............................................................................................................................... 5-3 5.5 CONVERTING CAD DATA TO A TIN ................................................................................................... 5-4 5.6 MERGING TINS .................................................................................................................................. 5-4 5.7 TRIANGULATION ................................................................................................................................ 5-7 5.8 AUTOMATED TIN EDITING ................................................................................................................ 5-8 5.9 CONVERTING A TIN TO DEM ............................................................................................................ 5-9 5.10 EXPORTING DATA TO CAD .............................................................................................................. 5-10

6 ADVANCED FEATURE OBJECTS ..................................................................................................... 6-1

6.1 OBJECTIVES ....................................................................................................................................... 6-1 6.2 DEFINING A WATERSHED WITH FEATURE OBJECTS ........................................................................... 6-1 6.3 MORE BASIN DELINEATION ............................................................................................................... 6-5 6.4 FEATURE OBJECTS FROM CAD DATA ................................................................................................ 6-8 6.5 CONCLUSION ..................................................................................................................................... 6-9

1 Introduction

CHAPTER 1 Introduction

In this first exercise you will get familiar with the WMS interface and help system. You should explore the different menus, modules and tools so that you have a good idea of the organization.

1.1 Exercise Files Each exercise has one or more files that have been prepared for you to use. You are instructed at various points to open these files. The default installation of WMS copies all of these files into a directory named “tutorial” (for example you will find them in C:\Program Files\WMS84\tutorial if you installed WMS in the default folder of C:\Program Files\WMS84). Further, the files for each exercise are organized by directory within the tutorial directory. Directories are named with abbreviations for the chapter name and the first time you open a file for each exercise you will be directed to open from the appropriate folder in the tutorial directory. Remaining files for a given exercise will be located in the same directory.

1.2 Starting Over It is suggested that you start WMS new at the beginning of each exercise. If you continue from one to another without quitting, then data, display options, and other WMS settings may not be in sync with the instructions, and may lead to confusion.

1-2 WMS Tutorials – Volume 1

1.3 Getting Around the WMS Interface The WMS Help file has a section on some of the basic elements of the WMS graphical user interface (GUI). The demonstration portion of this lesson covered most of the basic elements of the Quick Tour, but it is contained in the WMS Help file should you want to review later.

1.3.1 Self-Guided Tour The WMS Help file is located at http://www.xmswiki.com and contains basic information for some of the important elements of the GUI. In this section you should review these help pages and then practice on your own to understand how the interface works.

1. Start WMS

2. Select Help | WMS Help

3. Review these sections and then close the help page

4. Select File | Open

5. Locate the folder C:\Program Files\WMS84\tutorial\demedit

6. Open the file named “trailmount.dem”

7. Select OK


9. Open the file named “trailmountain.tif”

10. Select No if asked to convert your TIFF to a JPEG

As a minimum be sure that you are comfortable with the following operations within the WMS interface (if you have questions, search on the topic inside the WMS help page for further explanation):

• Switching modules

• Switching tools

• Zooming, panning, framing the image, and rotating in 3D

• When you are finished, use the Plan View macro to make sure you are in plan view before trying other things

http://www.xmswiki.com/�

Introduction 1-3

• Using the Display Options , Contour Options , and other macros

• Turning objects on and off and accessing menus from the Project Explorer

• Changing Display Options

• Adjusting Contour Options

• Saving a project file

Continue exploring the different elements of the interface and/or reviewing the information within the WMS Help page.

2 Images

CHAPTER 2 Images

Images are an important part of most projects developed using WMS. An image is comprised of a number of pixels (picture elements), each with its own color. The resolution, or size, of the pixels will determine the amount of area and detail represented in the image. Images are used in WMS to derive data such as roads, streams, confluences, land use, soils, etc. as well as providing a base map or “backdrop” to your watershed. In order to make use of images they must be georeferenced. Georeferencing an image defines appropriate x and y coordinates so that distances and areas computed from the image will be accurate. Because images are commonly used in Geographic Information System (GIS) programs like WMS, data developers often store the georeferencing information as either part of the image file (a geotiff file for example), or in a separate file commonly referred to as a “world” file.

2.1 Objectives In this exercise you will learn the primary ways that images are imported and georeferenced, or registered, by WMS. You will:

1. Learn how to use geotiff files

2. Learn how to use world files

3. Learn about image resolution

4. Learn how building pyramids affects image display

5. Learn how to register scanned images


6. Learn ways to download images using the Internet

2.2 Geotiff Files Geotiff images are files that store georeferencing information. This means that you do not have to specify coordinates when you read in the image – it is done for you automatically. You will also see how you can tile multiple images together.

2.2.1 Setting Preferences 1. Close all instances of WMS

2. Open WMS

3. Right-click in the Project Explorer below the tree contents and select Preferences in the pop-up menu that appears (or select Edit | Preferences)

4. Select the Image Preferences tab in the Preferences dialog

5. Verify that Image Pyramids is set to Always Build

6. Under TIFF->JPEG Conversion, make sure Convert to JPEG is set to Never Convert

7. Select OK

2.2.2 Tiling Images


2. Locate the folder C:\Program Files\WMS84\tutorial\images

3. Open “redridge.tif”

4. Right-click on the redridge image icon in the Project Explorer and choose the Crop Collar command

5. Choose the Zoom tool

6. Single-click on the image to zoom in

7. Keep zooming in until the display of the image is clear

8. Select the Frame macro

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10. Open “josephspeak.tif” (This is an adjacent 1:24000 map image.)

11. Right-click on the josephspeak image icon in the Project Explorer and choose the Crop Collar command

12. Try zooming in and see if you can see where the map seams are (hopefully you will have some difficulty, but if you look close enough you may be able to tell)


2.3 World Files Many image files do not contain georeferencing information. For example JPEG files do not have georeferencing “tags” in the file like TIFF images may have. Most organizations that make images available for use distribute world files containing the georeferencing information along with the image files. These world files usually have the same name as the corresponding TIFF or JPEG file, but with the extension .tfw (for JPEG files the extension is .jgw, or .jpgw). If you download a world file and are asked to supply a name for it, follow this naming convention. Use the following procedure to open a JPEG file and its corresponding georeferencing information in WMS:

1. Select File | New

2. Select No when asked if you want to save your changes


4. Open “richfield1.jpg”

Because there is a world file named richfield1.jpgw the image is automatically registered. If a world file for an image is not named with the .tfw (or, for a JPEG, it is not .jgw or jpgw), you would have the option of importing the world file from within the registration dialog.

The Richfield image and world files were obtained from the TerraServer web site (http://terraserver-usa.com/). You can get multiple images and tile them together as illustrated in the next few steps. This process will illustrate how properly georeferenced files overlap automatically (e.g. without the tediousness associated with tiling images). Thus, it is not necessary to be “exact” in obtaining images and files from a terrserver source; overlapping is not a problem.






You can zoom or pan and turn on/off the different images to explore how they can be viewed and used when overlapping.

2.4 Image Resolution Images are usually available in different resolutions. In this part of the exercise you will open topographic maps of the same area at different resolutions.




4. Open “tm4m.jpg”

5. Use the Zoom tool to zoom in on the image until you can see the individual pixels of the image



8. Select Display | View | Previous View

9. In the Project Explorer toggle the display of tm16m on and off to see the difference in resolution of the two images



12. Zoom in and toggle the display of the images on and off in order to observe and compare the resolutions of all three images

When you zoomed in on the three images, you may have noticed that as the map scale increased, the map showed less detail. “tm4m” shows much more detail than either “tm16m” or “tm32m”. Images are commonly available on a scale of 1:24000, 1:100000, or 1:25000. 1:24000 maps cover far less area than 1:100000 or 1:250000 maps, but they show much more detail (higher resolution). It would take thirty-two 1:24000 maps to cover the same area that is covered by one 1:100000 map. If you need a great amount of detail for your

Images 2-5

watershed, you may want to use the 1:24000 maps. However, if your watershed is very large, this size of map will provide too much detail. Thus, it would be difficult to see “the big picture” of your watershed, and a 1:100000 or 1:250000 scale map may be more appropriate.

2.5 Building Pyramids WMS 8.4 provides the option of building pyramids when each image file is opened. When pyramids are built multiple files of varying resolutions are saved by WMS so that when a large area of an image is viewed a lower, or coarser, resolution image is displayed. A higher, or finer, resolution image is displayed as you zoom in to view a smaller portion of the image. This is similar to an automatic resampling process. On the other hand, when image pyramids are not built, only the original resolution image is displayed.

The advantages of building pyramids include faster and clearer display of an image. Image display is faster due to lower resolution images being displayed for larger areas and higher resolution images being displayed for smaller areas. The clarity of image display improves in situations when the image resolution exceeds the display resolution of the screen, which often occurs as you view a large portion of a high resolution image.

Because WMS only builds pyramids for JPEG images you must convert TIFF images to the JPEG format in order to build pyramids. Image conversion can be performed by WMS either as you open the image or after opening the image. By default, WMS always builds pyramids when a JPEG image is opened or created through conversion. Nevertheless, this setting can be changed. In order to best see the difference between images with and without pyramids built, we will alter the default settings as follows:



3. Under Image Pyramids, select Prompt for Each Image

4. Under TIFF->JPEG Conversion, ensure that Convert to JPEG is set to Always Convert, and Save JPEG is set to Temporary Folder

5. Select OK

With the default image pyramids settings set, we are ready to examine the differences between building and not building pyramids. We will begin by opening a 1:24000 USGS quadrangle map without building pyramids, as follows:






The image is automatically converted from a TIFF image to a JPEG image based on the Image Preferences. This procedure may take a little bit of time.

10. Select Yes to build pyramids in the image pyramids inquiry

Notice the clarity of this topographic map. To see the differences associated with image pyramids, we will open the same file but will not build pyramids.


12. Select No if asked to save changes


14. Select No on the image pyramids inquiry

Notice that the contours of the topographic map are not as clearly defined, and that the overall look of the image is grainy when compared to when pyramids were built. Now we will reset the default image preferences.



17. Under Image Pyramids, select Always Build

18. Under TIFF->JPEG Conversion, ensure that Convert to JPEG is set to Never Convert, and Save JPEG is set to Temporary Folder

19. Select OK

2.6 Registering Scanned Images Sometimes you will not be able to obtain a geotiff image or an image with a world file. In this case, you will need to register the image manually. To do this, you will need to know the coordinates of three points on the image. These coordinates can be in a projected or geographic system. Before you scan your paper image, or download an image from the Internet, you will want to mark

Images 2-7

the three points you have selected so that you can easily find the points on the image when you register the image in WMS.

We will use a part of a soils file as a “scanned image” that will be used later to develop a soils coverage and then later to compute a composite curve number.


2. Select No if asked if you want to save your changes


4. Open “soils.tif”

An image representing soil types will appear in the Register Image dialog. Three small red X's are marked on the image (these are small and may be difficult to see). There are also three plus signs with the numbers 1, 2, and 3 by them (much larger and visible). You need to place the numbered plus signs over the small x’s and enter the appropriate coordinates in order to register the image.

5. Use the Point Selection tool to drag each red + over the corresponding X as shown in Figure 2-1. You may wish to place them close and then zoom in on the area for more accuracy. Once you zoom in there is a Frame tool that you can use to re-center the image so that you can zoom in on another registration point. Do your best to move each plus mark over the corresponding red X in the image.


Figure 2-1: Moving + Marks in Registration Dialog

2.6.1 Registering in Geographic Coordinates The coordinates for the three points are known in geographic (latitude/longitude) and so we will register using these coordinates and then convert to UTM afterwards. You can use the Convert Point dialog from the Edit menu to enter degrees-minutes-seconds and convert to decimal degrees if necessary, but in order to properly register the coordinates must be decimal degrees. Also you will notice that longitude values west of the prime meridian should be entered as negative.

1. Using the values listed in Table 2-1 to enter the appropriate x (longitude) and y (latitude) values for the three points

Table 2-1: Latitude and Longitude for soils.tif

Point Longitude (x) Latitude (y) 1 -112.481944 38.68500 2 -112.477222 38.57667 3 -112.330277 38.57611

Images 2-9

2. When you have correctly entered the three coordinates select OK in the Register Image dialog


If the image appears distorted or crooked, you may have entered the coordinates incorrectly or placed the + marks inaccurately

2.6.2 Converting the Coordinates to UTM Geographic coordinates are commonly used on maps because they provide a global reference for any point in the world. However, for engineering work a planimetric system is necessary. The Universal Transverse Mercator (UTM) projection is commonly used so we will convert the coordinate system from geographic to UTM.

1. Right-click on the soils image icon in the Project Explorer and choose the Coordinate Conversion option

2. Select the Global Projection radio button in the Object Projection section in the Reproject Object dialog

3. Select Set Projection

4. Select Geographic (Latitude/Longitude) from the Projection drop down box

5. Select NAD 83 from the Datum drop down box

6. Select OK

7. Set the Vertical System units to Meters


8. Toggle on the Specify check box in the Project Projection in the Reproject Object dialog

9. Select the Global Projection radio button


11. Set Projection to UTM, Datum to NAD 83, Planar Units to Meters, and Zone to 12 (114°W - 108° W – Northern Hemisphere)

12. Select OK

13. Set the Vertical System Units to Meters

14. Select OK

There is some distortion in the image as it is converted from geographic to UTM because a degree of longitude has a shorter distance the farther north you are, but this is normal. Any measurements taken now, or data created from the image, will have meters for coordinate values.

2.7 Internet Exercises The Internet contains many useful locations where images and other useful WMS modeling data can be downloaded. Any location that has a picture or an image of a map can provide useful information within WMS. The next two sections require Internet access and will give you practice downloading images and registering them for use in WMS.

2.7.1 Download Images from the TerraServer web site Aquaveo maintains an Internet site that points users to helpful data download locations. This site is found at: http://www.xmswiki.com/wiki/GSDA:GSDA. One of the sections on this page is to download DRG Images (maps and aerial photographs). Choose this option and then go to the TerraServer web site.

The TerraServer web site provides you with options to search by address, city, or clicking interactively on a map. Download a topographic map and/or aerial photograph for a location of interest (your hometown if nothing else comes to mind). Do not forget to get the world file. When downloading the world file, be sure to rename your world file to match the image name and have a “.jpgw” or a “.jpw” extension. You can find help on the GSDA website.

After you download your images make sure you can open them correctly in WMS.

Images 2-11

2.7.2 TerraServer and Web Services Recent advances in programming technologies include the possibility of running application services from remote computers over the internet. This capability is called a web service, and TerraServer includes a web service that WMS can call to download image and world files directly from the WMS application. Because TerraServer prepares world files in UTM NAD 83, it is important that the current coordinate system in WMS is defined to something other than Local so WMS can perform any necessary coordinate conversions. For this example you will load a portion of a DEM, convert the coordinates to UTM NAD83 and then use web services to download the topographic map and aerial photograph images.




4. Locate the folder C:\Program Files\WMS84\tutorial\dembasics\NED

5. Find and open the file named “ned_Richfield.hdr”

6. Select OK to import the NED DEM file

7. Select Yes to convert the coordinates of the DEM from geographic to a planimetric system

8. Toggle on the Specify check box in Project Projection

9. Select the Global Projection radio button.


11. Set the Projection to UTM, the Datum to NAD 83, the Planar Units to Meters, and the Zone to 12 (114°W - 108°W – Northern Hemisphere)

12. Select OK

13. Set the Vertical System Units to Meters

14. Select OK

You should now have a portion of DEM contoured and displayed. You will now load the topographic and aerial photograph images directly from TerraServer.

15. Select the Get Data tool


16. Drag a box around the extents of the contoured DEM to define the region you wish to download the image

17. Select the Web Services option

18. Turn on the TerraServer aerial photo and TerraServer topo options

19. Select OK

20. Define the name of the web files to be “CC”

21. Select Save

22. Select Yes to accept the default file naming convention for web files

23. Accept the suggested resolution of the images by selecting OK

24. Be patient; it may take 30 seconds to a minute to complete the download process. When it does complete you will see the aerial photograph and the topographic map for the box defined in the graphics window (hopefully covering the entire DEM area).

When finished the topographic map will come in on top of the aerial photograph, but you may control which one is displayed using their respective check boxes in the Project Explorer window. The lower the resolution the more detail you will see. You can go to a higher resolution than suggested but if you want a high resolution for a large area it could take several minutes to download (you should probably not try to get a higher resolution than one or two more levels than suggested).

Using the Virtual Earth map locator tool (included with WMS), you can find any location in the world. This locator tool, combined with the web service client tool in WMS, allows you to download aerial photographs and topographic maps for any location covered by Microsoft TerraServer data in the United States.

25. Select the Get Data From Map tool

26. In the Virtual Earth Map Locator window, select Map Options | Show Locator Tool menu command.

27. Enter Joseph, UT in the Where field and select the Find button.

28. Turn off the locator tool by selecting the Map Options | Show Locator Tool menu command again.

29. Select the OK button.

30. Select the Web Services option

Images 2-13

31. Turn on the TerraServer aerial photo and TerraServer topo options

32. Select OK

33. Define the name of the web files to be “CC1”

34. Select Save

35. Select Yes to accept the default file naming convention for web files

36. Accept the suggested resolution of the images by selecting OK

37. Once again, be patient as the images complete the download process. When the download process completes, you will see the aerial photograph and the topographic map for the box defined in the virtual earth map locator tool.

2.8 Conclusion In this exercise, you were taught how to open several types of images in WMS. You learned how to georeference images and build pyramids for displaying images. In particular, you should know:

1. How to use geotiff files

2. How to use world files

3. How to build pyramids

4. How to register images

3 Basic Feature Objects

CHAPTER 3 Basic Feature Objects

Feature objects are points, lines, and polygons organized in coverages by different attribute sets such as drainage features, land use, soils, time travel paths, cross sections, etc. The primary coverage in WMS is the drainage coverage, which holds drainage boundary polygons, stream lines, and outlet nodes. Most of the other coverages are secondary to the drainage coverage and are used to “map” other hydrologic parameters such as travel time or curve numbers. Feature objects are equivalent to GIS vector data, therefore, importing from GIS databases is one important way to create coverages in WMS. Another important method for creating feature object coverages is to digitize directly from the screen, using a georeferenced image in the background as a guide. In this exercise you will experiment with both methods, with the main focus being the use of the various tools and assigning attributes.

3.1 Objectives In this exercise you will learn the basics for creating and importing feature objects and managing different coverages. This includes the following:

1. Creating and editing feature objects

2. Defining feature object attributes

3. Creating coverages and specifying attribute sets

4. Using shapefiles

5. Using images to create feature objects


6. Managing multiple coverages

3.2 Creating and Editing Feature Objects The Terrain Data, Drainage, and Map modules are where the feature objects are created and manipulated. All feature objects are made from a set of points and the lines connecting the points. There are three main types of feature objects: points, arcs, and polygons. The following steps will teach you how to create and edit the different types of feature objects.

1. Close all instances of WMS

2. Open WMS

3. Switch to the Map module


5. Locate the folder C:\Program Files\WMS84\tutorial\feature

6. Open “FeatureObjects.jpg”

This is just a picture of feature objects that you will use to trace and create feature objects. Do not be confused that it already “looks” like the feature objects are created.

3.2.1 Creating Feature Arcs 1. Find the portion of the image labeled Vertices, Nodes, and Arcs

2. Choose the Create Feature Arc tool

3. Single-click on the image near the point labeled 1

4. Double-click on the image near point 2 to end the arc

While you are creating a feature arc, you can press Esc to cancel, Backspace to back up one vertex, Enter or single-click to make a vertex, and double-click to end the arc. When WMS creates an arc, each end is a node and all points in the middle are vertices.

5. Single-click at point 3, directly on top of the arc you just made

6. Double-click at point 4 to end the arc

Notice how WMS automatically links the new arc to the existing arc and creates a node at the point of intersection.

Basic Feature Objects 3-3

7. Single-click at point 5

8. Double-click at point 6

3.2.2 Inserting Vertices and Snapping Arcs Oftentimes you will have two arcs very close to each other that should share a common node, but do not. WMS has an option to snap these nodes together.

1. Choose the Create Feature Vertex tool

2. Single-click on the arc where it is labeled 7

A vertex is inserted here just as if you had clicked here when creating the arc originally. You must create a vertex at this location so that the arc can be “snapped” to this location.

3. Choose the Select Feature Point/Node tool

4. Right-click on the node labeled 5 and select Clean on the pop-up menu.

5. Make sure the Snap selected nodes option is checked

6. Select OK

At the bottom of the WMS screen, you will notice the help script is prompting you to select a snapping point.

7. Select the vertex you just created (labeled 7).

WMS snaps the two arcs together and changes the vertex at point 7 to a node.

3.2.3 Deleting a Portion of an Arc Now that the main arc you created has two nodes along its length, you can delete the center portion only.

1. Choose the Select Feature Arc tool

2. Select the portion of the arc between nodes 3 and 7

3. Press the DELETE key, or right click and select ‘Delete’, to delete the arc

4. Select OK


You can also create arcs between two existing nodes. Practice this by reforming the arc that you just deleted.


6. Click on the node labeled 3

7. Click on the node labeled 7 to re-form the arc

3.2.4 Converting Vertices to Nodes WMS uses vertices and nodes for different purposes. For example nodes can have attributes while vertices simply define the shape or position of the arc. Sometimes you will need to change a vertex to a node or a node to a vertex.

1. Choose the Create Feature Vertex tool

2. Click on the arc somewhere between nodes 3 and 7

3. Choose the Select Feature Vertex tool

4. Right-click on the vertex you just made and select Vertex <-> Node on the pop-up menu.

You should now see a red node at this location. You have effectively broken the arc in half. You have also made it possible to define attributes (e.g. a drainage outlet) at this location.

3.2.5 Converting Nodes to Vertices Just as you can change vertices to nodes, you can change nodes to vertices. It is not necessary in most cases to do this, but can leave you with a “cleaner” representation of your feature arcs. For example you now have to manage and assign attributes to one arc instead of two because converting a vertex to a node merges two arcs together.


2. Right-click on the node you just converted and select Node <-> Vertex on the pop-up menu.

You can see that the node has been changed back to a vertex.

3.2.6 Building Polygons Find the portion of the image labeled Polygons.



2. Single-click at the point labeled 1 on polygon A

3. Single-click on points 2 through 10

4. Single-click on point 1 again to end

5. Trace polygon B in the same manner

You should now have two closed loops made out of the arcs just created. They are not polygons at this time – they are still just arcs.

6. Right-click on the Drainage coverage and select Build Polygon on the pop-up menu.

7. Select OK to use all the arcs

The two polygons should now be drawn with a thick line instead of the thinner arc lines. Polygons are built from their constituent arcs and it is during the build polygon function that the appropriate topology is established.

3.2.7 Assigning Attributes Each of the nodes, arcs, and polygons you created were created with default properties or attributes. WMS allows you to change the attributes of feature objects.

1. Choose the Select Feature Arc Tool

2. While holding the SHIFT key down, select (multi-select) all 5 arc sections in the Vertices, Nodes, and Arcs portion of the image

3. Select Feature Objects | Attributes

A dialog will come up allowing you to choose whether you want the arcs to have the Generic, Stream, Pipe, Lake, or Ridge attribute.

4. Select the Stream option

5. Select OK

The arcs should now be colored blue. Each arc portion should have a small blue arrow on it. These arrows show the way the stream you have created flows. The original direction you created the arc determines the way the stream flows now. Stream arcs should always be created from downstream to upstream. You should also be able to see that the lower node on the arc looks different now. WMS has automatically changed it to a drainage outlet instead of a generic node.



7. Double-click on the lower node (now an outlet)

A dialog comes up showing that the node now has the Drainage outlet attribute. For any feature object (point, line, arc) you can select and then choose the Attributes command from the Feature Objects menu, or double-click to bring up the attributes dialog.

8. Select OK

Just as you can change the attributes of arcs and nodes, you can change the attributes of polygons.

9. Choose the Select Feature Polygon tool

10. Double-click anywhere inside Polygon A in the polygons portion of the image

11. Select the Drainage boundary type

12. Select OK

Polygon A should now be drawn in a thick colored line.

13. Double-click anywhere inside Polygon B

14. Select the Lake/Reservoir type

15. Select OK

Polygon B should now be drawn in light blue.

3.3 Using Shapefiles to Create Feature Objects One of the most important features of WMS is the ability to automatically create feature objects using shapefiles.



You will import shapefile data differently depending on whether the computer you are working on has ArcView installed on it or not. For this exercise, the two ways are basically equivalent. However, if you have ArcView installed, you have access to more data types and display options.


3.3.1 Importing a Shapefile and Mapping to Feature Objects 1. Right-click on “GIS Layers” in the Project Explorer and select Add

Shapefile data.

2. Open “streams.shp”

In order for the shapefile to work correctly, streams.dbf and streams.shx must be located in the same directory as streams.shp. This is true for all shapefiles.

3. Choose the Select Shapes tool

4. Draw a box around all the shapes to select them all

5. Select Mapping | Shapes -> Feature Objects

This is the GIS to Feature Objects Wizard. It is used to map shapefile data to feature objects in WMS.

6. Choose Next

The spreadsheet that is presented shows each shapefile attribute in capitalized letters. In this file, you should see DRAINTYPE, LENGTH, SLOPE, etc. Underneath each attribute is a dropdown box containing the WMS attributes you can choose to map the shapefile attributes to.

7. The DRAINTYPE attribute should be mapped to Drainage Arc type

8. The LENGTH attribute should be mapped to Stream length

9. The SLOPE attribute should be mapped to Stream slope

10. The DMANNINGS attribute should not be mapped (Not mapped)

This attribute cannot be mapped because there is not a corresponding WMS attribute available to map it to.

11. The BASINID attribute should be mapped to Stream basin id

You can scroll through the mapping spreadsheet to see the value that is assigned to each attribute for each shape.

12. Click Next

13. Click Finish

14. Toggle off the streams.shp shapefile in the Project Explorer to see result of mapping the shapefile to WMS feature objects.


You have now imported a shapefile containing streams and basins, converted all the shapes to WMS feature objects, and mapped data from the original shapefile to WMS attributes.

3.4 Creating Feature Objects Using Background Images Another important feature of WMS is the ability to create feature objects using background images as guides. For instance, you may have a soil use map you want to read into WMS. The following procedure explains how this is done.

3.4.1 The Project Explorer First, you will need to create a new coverage by utilizing the Project Explorer on the left hand side of the WMS main window.

The Project Explorer displays and allows users to manage the current coverages and data in WMS.


2. Select No if asked if you want to save your changes

In the Project Explorer, you should see a folder entitled Map Data. You should also see the default coverage listed (always a Drainage coverage when beginning a new project) in the Coverages folder. From the Project Explorer, you can manage the default coverage, make new coverages, delete coverages, edit coverage properties, and change the active coverage.

3. Right-click on the existing coverage in the Project Explorer, named Drainage

4. Select Rename

5. Enter PracticeDrainage for the new coverage name

6. Right-click on the Coverages folder

7. Select New Coverage

8. From the Coverage type dropdown box, select Soil Type

9. Notice that the coverage name is automatically changed to Soil Type

10. Select OK

11. Click on the PracticeDrainage coverage


You can see that this coverage shows up in color and bold, while the Soil Type drainage is in gray and regular font. This means that the PracticeDrainage coverage is the active coverage.

12. Select the Soil Type coverage to make it active

13. Uncheck the box next to the PracticeDrainage coverage

14. Now the PracticeDrainage coverage is not visible. Turn this coverage back on to make it visible again.

3.4.2 Reading in Images Now that you have added a soil type coverage, you can read in the soils image.


2. Open “soils.img”

3.4.3 Manually Digitizing Feature Objects


2. Make sure that the Soil Type coverage is selected

3. Starting anywhere on the border of the large orange area, outline the entire region, labeled D, with an arc

You can be as accurate as you like. If you wish, you can even zoom in to get a closer view of the image. You will have to end the arc by double-clicking in order to be able to select any other tools, such as zoom, pan, or show all. Once you have zoomed to the location you want, you can just pick up where you left off. Remember that when you click near an existing vertex or arc, WMS will automatically snap the new arc to the existing one.

4. Outline all the other soil type polygons similarly, without creating arcs on top of previously defined borders

NOTE: When outlining the other regions, simply start somewhere on the previously created arc and proceed around a border without re-drawing where another border has already been defined by arcs.

5. Right-click on the Soil Type coverage and select Build Polygon

6. Select OK to use all the arcs


Check to make sure that each soil use polygon is completely outlined. If one or more polygons do not build correctly, check to be sure that the arcs surrounding the polygons are completely closed.

3.4.4 Assigning Feature Polygon Attributes Now that you have created the soil use polygons, you will need to assign the soil use attributes to the correct polygons.

1. Choose the Select Feature Polygon tool

2. Double-click on the yellow polygon labeled B

The Soil type mapping dialog should come up automatically. Just as in the first part of the exercise, double-clicking on a feature object brings up a dialog allowing you to select or edit its attributes. Since you are now using a Soil Type coverage, the automatic attribute for a polygon is Soil Type.

3. Choose the Add soil ID to list button

4. Choose this button two more times, so that there are four soil types in the list box

We will now assign soil types to the WMS Soil IDs.

5. Under Soil type properties, notice the drop-down buttons used to assign relationships to the Soil IDs

6. Soil ID 0 should be assigned to Soil Type A

7. Soil ID 1 should be assigned to Soil Type B

8. Soil ID 2 should be assigned to Soil Type C

9. Soil ID 3 should be assigned to Soil Type D

10. Since the polygon we clicked on originally is Type B, select Soil ID 1 from the WMS soil ID list and choose the Apply button

11. Double-click on the polygon labeled A

12. Select Soil ID 0 from the WMS soil ID list and choose Apply

13. Similarly, assign Soil ID 2 to all the polygons labeled C and Soil ID 3 to all the polygons labeled D

14. Make sure each polygon has the proper Soil ID assigned by double-clicking on each and checking the soil type in the Selected Soil Properties box


3.5 More Feature Objects from Images WMS handles land use images the same as it does soil type images. You will now read in a land use image, digitize polygons, and assign land uses. You need the land use image (and the resulting land use polygons) to be on its own coverage, so you will need to create a land use coverage.

1. Right-click on the Coverages folder in the Project Explorer

2. Select New Coverage

3. From the Coverage type dropdown box, select Land Use

4. Select OK

Usually you would open the land use image and digitize the land use polygons yourself. Here, you will open a completed file. To use the completed file, complete the following steps:


6. Open “luse.map”

If you were digitizing the image yourself, you would complete the following steps:

1. Select Images | Import

2. Open “luse.img”

As outlined in Parts 3.4.3 and 3.4.4, you would trace all the land use polygons with arc segments (while in the Map module), build polygons, and then map the land use IDs to the correct polygons.

3.6 Display Options WMS has many display options to help you tailor the look of your project to your needs. You can change options such as polygon colors, presence of nodes and vertices, and legends using the Display Options command.

1. Right-click on the Soil Type coverage and select Display Options on the pop-up menu.

2. On the Map tab, check the Color Fill Polygons box

3. Uncheck the Points/Nodes and Vertices boxes


4. Choose the Soil Type Display Options button at the bottom of the spreadsheet

5. Select the first Soil ID listed in the list box and click on the color square to the right

6. Choose a new color from the color palette

7. Change the colors of the other soil groups uses if you desire

8. Select OK

9. Check the Soil Type Legend box

10. Select OK once again to exit the Display Options dialog

You can continue to explore the display options if you wish. If you wanted to assign new colors to the land uses, you would need to make the land use coverage active before going back into the Display Options dialog or switch to Land Use in the coverage type combobox

3.6.1 Managing Coverages Using the Project Explorer, you can choose to hide and/or show coverages and designate which coverage is the active coverage

1. From the Project Explorer, toggle off the check boxes for the PracticeDrainage and the Soil Type coverages

2. Click on the land use coverage so it will be active

Now only the land use coverage will be visible on the screen. The other coverages still exist; they simply will not show on the screen until you turn their visibility back on.

3.7 Conclusion In this exercise you should have learned the basics for creating and importing feature objects and managing different coverages. Both these concepts are central to your understanding of WMS. You should now be able to:

1. Create and edit feature objects

2. Set feature object attributes

3. Create coverages and specify coverage attribute sets

4. Import shapefiles


5. Use images to create feature objects

6. Manage multiple coverages

7. Import and edit feature objects from DXF data

4 DEM Basics

CHAPTER 4 DEM Basics

Digital Elevation Models (DEMs) are the most commonly available digital elevation source and therefore an important part of using WMS for watershed characterization. A DEM is a rigid data structure that contains a two-dimensional array of elevations where the spacing between elevations is constant in the x and y directions. In the US, DEMs are downloadable from the Internet at 30-meter (1:24,000 map series) and 90-meter (1:250000 map series) resolutions. The USGS has recently deployed the National Elevation Dataset which is a continuous elevation map at 30-meter resolution. Blocks of 100 MB or less can be downloaded for free from the NED website.

The Arc/Info ASCII grid format is common throughout the GIS world and is common outside the US. The basics of downloading, importing, editing, and displaying DEMs will be demonstrated in this exercise. Actually using the DEM for watershed delineation is the subject of the next chapter.

4.1 Objectives In this exercise you will learn the basics of importing, viewing and preparing DEMs for automated watershed delineation. This includes the following:

1. Importing USGS DEMs from different formats

2. Tiling multiple DEMs together

3. Editing DEM elevations

4. Setting DEM display options


4.2 Getting DEMs from the Internet In this part of the exercise, you will learn how to download DEM data from the National Elevation Dataset website at http://ned.usgs.gov/. Instead of bookmarking this site, you can bookmark the GeoSpatial Data Acquisition (GSDA) homepage: http://xmswiki.com/wiki/GSDA:GSDA. This site contains links to this and many other sites where you can get DEM data.

If you do not have an Internet connection you can still work through this exercise using the files which have been downloaded already and placed in the tutorial directories by skipping ahead to section 4.3 now.

4.2.1 USGS National Elevation Dataset The USGS National Elevation Dataset (NED) provides continuous 1:24,000-scaled DEM data for all of the contiguous US and 1:63,360-scale DEM data for Alaska. To access this data, complete the following steps:

1. Go to http://seamless.usgs.gov, and then click on View and Download United States Data. (You could also go to GSDA site and click on DEM, then click on DEM Data from USGS Seamless Map)

2. Choose the Find tool and type in “Richfield”

3. Click the OK button

4. Find the Richfield in SEVIER county, UT and click Goto

5. On the Display Tab on the right of the screen, click on the arrow next to Hydrography

6. Select the check boxes next to National Atlas and NHD Streams and National Atlas and NHD Waterbodies as shown in Figure 4-1. The map should automatically update.

http://ned.usgs.gov/�

http://xmswiki.com/wiki/GSDA:GSDA�

http://seamless.usgs.gov/�

http://www.emrl.byu.edu/gsda�

DEM Basics 4-3

Figure 4-1: Display Layers

7. Use the Zoom tool to frame the area shown in Figure 4-2


Figure 4-2: Zoom Window

8. Under the Download section, choose the Download Area tool

9. Make the rectangle shown in Figure 4-3. An order confirmation page should come up

Figure 4-3: Download Selection Window

DEM Basics 4-5

4.2.1.1 Getting the Format Correct By default the DEMs are downloaded in a format (binary ArcGrid) that WMS cannot read. However there are options for the data like the file format that can be changed. Using the Modify Data Request option you can change the file format from ArcGrid to GridFloat. The GridFloat format is recognized by WMS. Here is how you do it:

1. Select the Modify Data Request button

2. Select GridFloat from the Data Format drop down box next to National Elevation Dataset (NED) 1 Arc Second

3. Select the Save Changes & Return to Summary button

4. If you are using Internet Explorer as your browser, hold down the Ctrl key and click the Download link when the request summary page displays again. Keep the Ctrl key pressed until after you select the Save button to save your file. Save the .zip file to a location where you can unzip it

5. Use WinZip, or any unzipping utility to unzip the file that you download. If you were not successful downloading the DEM data you can use the DEM file located in the NED directory

If you wish, you can open this DEM in WMS.


7. Open WMS


9. Locate the folder C:\Program Files\WMS84\tutorial\dembasics (or wherever you saved your files)

10. Open “ned_Richfield.hdr” (or the .hdr file within the NED directory you downloaded and unzipped)

11. Select OK

12. Select No when prompted to convert coordinates

WMS should read in the DEM, and it should be similar to other DEM files you have read in.


4.3 Merging DEMs The area you are studying may lie across two or more DEM quads. WMS is able to merge multiple DEM files that span quad sheets. To see how this works, complete the following steps:



3. Locate the folder C:\Program Files\WMS84\tutorial\dembasics

4. Find and multi-select “josephpeak.dem”, “redridge.dem”, “marysvalecanyon.dem”, and “trailmountain.dem”

5. Choose Open

You will be taken to the Importing USGS DEMs manager. The area covered by the DEM you have selected will be colored in a box near the center of the dialog. The boundaries of your DEM area will show up in the four edit boxes.

6. Select OK

By multi-selecting the DEMs you want, you can read in all the quads you need at the same time. WMS is able to read in an unlimited number of DEMs at a time (unless your computer runs out of memory). You can read in multiple DEMs in the standard USGS format (from the WebGIS site), the SDTS format, or Arc/Info ASCII grid format, but you cannot mix and match formats in WMS (you could export any DEM in the Arc/Info ASCII grid format in order to get them all to a common format, though). You cannot tile multiple DEMs from the NED site (this should not be a problem though since the data from this site is “seamless” in the first place).

4.4 Trimming DEMs WMS allows you to select the portion of the DEM you need and eliminate all of the surrounding elevation points. This can be done either with an existing polygon or with a polygon entered interactively.

4.4.1 Trimming DEMs 1. Right-click on DEM in the Project Explorer and select Trim | Polygon

2. Choose the Enter a polygon interactively option

DEM Basics 4-7

3. Select OK

4. Click each of the four vertices of the polygon shown in Figure 4-4, double-clicking on the last to close the polygon

Figure 4-4: DEM Trim Area

4.5 Displaying DEMs

4.5.1 Contour Options WMS has several options for displaying DEMs. You can change the contour display options by following these steps:

1. Right-click on DEM in the Project Explorer and select Contour Options… in the pop-up menu

2. Under Contour Interval, select Number of Contours and set the edit box value to 10

3. Select OK

You can see that there are fewer contours and they are spread farther out now.

4. Right-click on DEM in the Project Explorer and select Contour Options… in the pop-up menu

5. Under Contour Method, select Color Fill


This option will “color in” the contours.

6. Choose the Legend button

7. Under Legend Specifications, check the Display Legend check box

8. Select OK twice

You can go back into the Contour options dialog and explore more of the contour display options if you wish.

4.5.2 Point Display Step Next you will explore the point display step option:

1. Right-click on DEM in the Project Explorer and select Display Options in the pop-up menu.

2. Change the number in the Point Display Step edit box to 4

3. Select OK

You can see that the display is not as smooth now.

4. Right-click on DEM in the Project Explorer and select Display Options in the pop-up menu.

5. Change the Point Display Step to 12

6. Select OK

7. Change the Point Display Step back to 2

Raising the point display step will allow your DEM display to refresh noticeably faster, especially if your computer is slow. Although WMS is not drawing every DEM point, each point that was read in is still there, so changing the point display step does not change the accuracy.

4.5.3 Shading Options Now you will explore the shading options:

1. Select Display | Display Options

2. Select Lighting Options

3. Toggle on Use light source

DEM Basics 4-9

4. Click on the globe to move the light source and adjust the slide bar to change the amount of ambient light

5. Select OK

Changing the position of the light source and the ambient light alters the display of the DEM. You can experiment with these options to accentuate the elevations that are most important for you to see.

4.5.4 Views Many times it is easier to see the DEM elevations from a view other than the plan view.

1. Select Display | View | Oblique View. (Alternatively, you can also select the Perspective View macro )

It is now much easier to see the changes in elevation on the DEM. If the elevation relief cannot be seen clearly, you can change the Z-magnification to accentuate the elevation relief.

2. Select Display | View-Z Magnification

3. Enter 3 in the edit box.

4. Select OK

The image will redraw on its own. You will see the elevation relief better now.

4.6 Conclusion DEM data for the United States is found in several places on the Internet. Data is available for most areas of the US and some parts of other countries. DEM data is very useful for delineating watersheds in WMS.

In this exercise you should have learned how to do the following:

1. Import USGS DEMs in different formats

2. Tile multiple DEMs together and edit DEM elevations

3. Set DEM display options

5 Using Triangulated Irregular Networks

CHAPTER 5 Using Triangulated Irregular Networks

Triangulated Irregular Networks (TINs) are constructed from a scattered set of xyz vertices. They can be used for visualization, as background elevation maps for generating new TINs or DEMs, or to obtain cross sections for hydraulic models. WMS has powerful tools for importing and manipulating TIN data.

5.1 Objectives The following topics will be covered in this exercise:

1. Importing survey data

2. Digitizing data

3. Triangulation

4. Automated TIN editing

5. Manual TIN editing

6. Creating a TIN using a conceptual model

7. Converting a TIN to a DEM

8. Exporting data to CAD


5.2 Importing Survey Data 1. Close all instances of WMS

2. Open WMS


4. Locate the Folder C:\Program Files\WMS84\tutorial\tins

5. Open “surveytm.txt”

6. Leave the default settings. This is a tab delimited file exported from Excel. Select Next

7. For WMS data type choose Survey Data

8. In the File preview spreadsheet, ensure that the first, second, and third column types are mapped to X, Y, and Z, respectively

9. Select Finish

10. Right-click on surveytm under Terrain Data in the Project Explorer and select Display Options in the pop-up menu.

11. Toggle Unlocked Vertices on in the Tin Data tab

12. Select OK

You should now see the points from the surveytm.txt file your read.

13. Select Edit | Current Coordinates to set your current coordinates

14. Select the Global Projection option


16. Set Projection to UTM, Datum to NAD 27, Planar Units to Meters, and Zone to 12 (114°W - 108°W – Northern Hemisphere)

17. Select OK

18. Set Vertical Units to U.S. Survey Feet

19. Select OK

Using Triangulated Irregular Networks 5-3

5.3 Getting a Background Image Skip section 5.3.1 if you are not able to connect to the Internet using your computer.

5.3.1 Getting a Background Image Using TerraServer

Using an Internet connection we will now download the topographic map image directly from TerraServer and open it in WMS.

1. Select the Get Data tool

2. Drag a box around the extents of TIN vertices to define the region of the image

3. Toggle on the TerraServer topo option

4. Select OK to start the downloading process

5. Enter “TrailMtn” and click Save

6. Click Yes to accept the default file format for web files

7. Select OK to accept the suggested resolution. It may take 30 seconds to one minute to complete the downloading process.

WMS will automatically open the image after downloading it. If you were able to successfully complete all the steps in this section you can skip section 5.3.2.

5.3.2 Open Background Image


2. Open “trailmountain.tif”

3. Zoom in around the vertices

5.4 Digitizing Data 1. Select Display | Toolbars | Digitize to turn on the Digitize toolbar at

the bottom of the screen

2. Click on the Digitize Mode button, which is located on the Digitize toolbar, to turn on the digitize mode


3. Enter a Z value of 6800 ft in the white box

4. In the terrain data module , select the Add Vertices tool from the TIN toolbar (make sure you do not select the Create Feature Point tool from the Feature Objects toolbar—it looks the same as the Add Vertices tool)

5. Digitize the 6800 ft contour by using the background image to add vertices

6. Click on the Digitize Mode button, which is located on the Digitize toolbar, to turn off the digitize mode

7. Select Display | Toolbars | Digitize to turn off the Digitize toolbar at the bottom of the screen

5.5 Converting CAD Data to a TIN Often terrain data is stored or processed in a CAD program in the form of contours or triangles. In either case the 3D data points (x,y,z) can be converted from the CAD data to TIN points and triangulated in WMS.


2. Select No when asked if you want to save changes


4. Open “contours.dwg”


6. Select CAD | CAD->TIN

7. Select OK

The points defining the contour lines contain x, y, and z coordinates so when the points are converted to TIN points and retriangulated, you are left with a 3D TIN surface. You can zoom in, rotate, change the display or contour options in order to better visualize your TIN if you would like. You can also read other CAD files with 3D points and convert them to a WMS TIN.

5.6 Merging TINs Sometimes, especially when building a hydraulic model, you will want to merge elevation data from different sources together into a single TIN or DEM.


For example, you might have survey data that represents the bathymetry of a stream channel stored as contours in a CAD program that you want to merge with DEM data from the USGS. Merging data from several sources can be especially useful for hydraulic modeling applications. In many hydraulic modeling applications you need to “cut” cross sections that include both the channel geometry (obtained from a survey of the channel) and the floodplain (obtained from a USGS DEM).

Merging two or more elevation data sources into a single TIN is a 3-step process. First, you need to make sure the coordinate systems of each set of elevation data match each other…all the elevation data needs to “line up” and all the elevations should either be in US Customary or SI units. Second, convert each set of elevation data to a separate TIN. Third, merge all of your TINs into a single TIN using the merge TINs command. This section of the tutorial will show how these three steps are used to merge separate elevation sources in the WMS.



3. Open “tmcontours.dwg”

“tmcontours.dwg” is a DWG file from a CAD program containing contours for a small area. You want to merge the elevation data in this file with data from a DEM. First, you will convert this DWG file to a TIN. To convert this file, you first want to convert these contour lines to arcs. Then, you will redistribute vertices on the arcs. Finally, you will convert the arcs with the redistributed vertices to a TIN. When you have contour lines, you normally do not want to convert them directly to a TIN because the vertices along each contour line might be at a random or undesirable spacing to generate a quality TIN.


5. Select CAD | CAD -> Feature Objects

6. Turn off all the layers except CAD layers_arcs

7. Select OK

8. Change the Coverage type to General and select OK to create the CAD layers coverage

9. Select CAD | Delete

10. Select the Select Feature Arc tool

11. Use Edit | Select All to select all feature arcs


12. Select Feature Objects | Redistribute

13. Enter a Spacing of 20

14. Select OK

When you redistribute the vertices, WMS interpolates elevations for any new vertices on the arc from existing arc vertices. You have now redistributed the vertices on the arcs to a good spacing and are ready to convert the contours to a TIN.

15. Select Feature Objects | Arcs -> TIN Vertices

16. Right-click on the TIN that was created (New tin) in the project explorer and select Triangles | Triangulate on the pop-up menu


18. Select Feature Objects | Delete to delete all of your original contour data from this session of WMS

19. Select OK to clear all of your map module data


21. Open “trailmountain.dem”

22. Select OK in the “Importing USGS DEMs” dialog

You have now read a USGS DEM. To merge this DEM with the TIN you have just created from the CAD contours, you need to convert the DEM to a TIN and make sure all your TINs are in the same coordinate system. Currently, the XY coordinates of your DEM and TIN are in meters in the same UTM coordinate system, but the elevations on your DEM are in Meters while the elevations on your TIN are in feet.

23. Under Terrain Data in the project explorer, right-click on the New tin and rename the TIN to “CAD Contours”

24. Right-click on the DEM and select Convert | DEM -> TIN | All

25. Turn on the Delete DEM option (leave everything else as originally set) and select OK

26. In the project explorer, right-click on the “CAD Contours” TIN and select Coordinate Conversion

27. Select the Global Projection radio button in the Object Projection section in the Reproject Object dialog


28. Set Projection to UTM, Datum to NAD 27, Planar Units to Meters, and Zone to 12 (114°W - 108° W – Northern Hemisphere)

29. Select OK

30. Set the Vertical Projection to NGVD 29(US) and the Units to U.S. Survey Feet

31. Select OK

32. In the project explorer, right-click on the “CAD Contours” TIN and select Merge

33. In the Merge TINs dialog, select the All –> button.

To merge these TINs together and delete any regions of overlap between the TINs, you must order your TINs in the correct order in the list of TINs to merge. They should be ordered in the priority used for merging TINs. Put your least accurate TIN at the top, the most accurate at the bottom.

34. Select the Delete overlapping regions button.

35. Move your TINs up or down so the CAD Contours TIN is at the bottom and the TIN from your DEM (New tin) is at the top.

36. Select OK and wait while your merged TIN is generated from your existing TINs.

37. Select OK

38. In the project explorer, select the CAD Contours and New tin TINs and hit the Delete key to remove these TINs now that you are done with them.

You have now created a merged TIN that is a combination between your CAD contours and your USGS DEM. You could use this TIN for hydraulic modeling or could convert this TIN to a DEM so it can be used for hydrologic modeling.

5.7 Triangulation In order to edit the TIN according to the steps in this exercise we will delete the existing data and read in a TIN file before we triangulate the data.




41. Open “digitizetm.tin”

42. Right-click on the TIN (New tin) in the Project Explorer and select Triangles | Triangulate on the pop-up menu.

5.8 Automated TIN Editing WMS has automated methods of editing TINs to provide a representation of terrain that is useful for drainage analysis. These methods include data transformations and eliminating flat triangles and pits. Data transformations may be useful for repositioning data if it is not originally located in the correct position because of survey errors or an unknown coordinate system. After transforming coordinates, you should always set your current coordinate system if it is known. Capabilities to eliminate flat triangles and pits still exist in WMS, but they are seldom needed since flat triangles and pits pose few problems when using the DEM-based watershed delineation tools in WMS.

5.8.1 Transformations Run the cursor over the TIN and notice that the z values in the help strip at the bottom of the WMS window are in feet. The XY values on this particular TIN are in meters, and you want the X, Y, and Z units all in meters so they match when you delineate a watershed. In this section, you will convert the Z values from feet to meters. You would normally do this using the coordinate conversion tool. This section simply demonstrates how the transform tool works.

1. Select TIN | Vertices | Transform

2. Enter 0.3048 for the Z Scale value to scale the elevations in feet to meters

Notice that there are several other options for transforming TIN vertices, including options to translate and rotate vertices on the entire TIN.

3. Toggle on the Frame image after transformation option

4. Select OK

Run the cursor over the TIN and notice that the z values in the help strip are now in meters.


5.9 Converting a TIN to a DEM If you are delineating a watershed, you will want to convert your TIN to a DEM. This section demonstrates how to delineate a watershed from a TIN by converting the TIN to a DEM.

1. Right-click on the TIN (New tin) in the Project Explorer and select Convert | TIN->DEM on the pop-up menu.

2. Enter a cell width and cell height of 10

3. Select OK

4. Select Yes

5. Switch to the Drainage module

6. Select DEM | Compute TOPAZ Flow Data

7. Select OK

8. Select OK

9. Select Close once TOPAZ finishes running (you may have to wait a few seconds to a minute or so)


11. Select DEM Data and change the Minimum Accumulation For Display to 0.05 mi2

12. Select OK

13. Select the Create Outlet Point tool

14. Create an outlet as shown in Figure 5-1


Figure 5-1: DEM outlet

15. Select DEM | Delineate Basins Wizard

16. Select Delineate Watershed

17. Select Close

18. A drainage boundary is created using the DEM data. The basin data for this drainage basin is computed

5.10 Exporting Data to CAD Data that is visible on the screen can be converted to CAD data and then saved for use in CAD programs.


2. Select CAD | Data -> CAD

In order to view only the newly created CAD data we will hide all other data.

3. Hide the Map Data Coverages folder in the Project Explorer by toggling its visibility check box off

4. Hide the Terrain Data folder in the Project Explorer


6. Select DEM Data and toggle Color Fill Drainage Basins and Fill Basin Boundary Only off


7. Select OK

8. Select CAD | Display Options

9. In the Visibility column toggle “Drainage_arcs” off

10. Select Apply. Notice the CAD data that disappears when selecting this button

11. Select Cancel

12. Select File | Save As

13. For Save as type choose the DWG files (*.dwg) filter

14. Enter a filename and select Save

6 Advanced Feature Objects

CHAPTER 6 Advanced Feature Objects

In a previous exercise (chapter 3) you learned how feature points, lines, and polygons are created and organized into coverages. In this exercise you will continue to learn about the creation and editing of feature objects, with a focus on creating drainage coverages, the primary coverage used in WMS to develop watershed models.

6.1 Objectives In this exercise you will learn the how to create and import feature objects and manage different coverages. This includes the following:

1. Using feature object drainage coverages for watershed delineation

2. Advanced feature object editing functions

3. Assigning appropriate feature object attributes

4. Importing and editing feature objects from CAD data

6.2 Defining a Watershed with Feature Objects By using a combination of stream arcs, outlet nodes, and basin polygons, you can develop an entire watershed without the use of a digital terrain model. The watershed can be to scale or a schematic. Of course, if it were not to scale, polygon areas and stream lengths would not be valid for your hydrologic model.


In this section of the exercise you will create the Aspen Grove watershed from an image of a scanned paper map with clearly marked streams and basin boundaries.


2. Open WMS



5. Locate the folder C:\Program Files\WMS84\tutorial\featureadv

6. Open “aspentrc.img”

You should see a portion of a USGS quad map with basin boundaries outlined in red and the stream network in black.

6.2.1 Creating Basin Boundaries We will begin by creating the basin boundaries, but it does not matter whether the basins or streams are created first.



3. Make sure that the arc type is Generic and Select OK

4. Beginning at the outlet point (lower right) trace out the entire watershed boundary. You do not need to follow every detail; take as much time as you want.

5. Now create each of the three sub-basin boundary arcs on the interior of the watershed. Begin by clicking on a point near the junction in the center of the watershed and ending by clicking near the intersection of the arc previously created for the exterior boundary.

6.2.2 Creating the Stream Network The stream network is created in much the same way the basin boundaries were. The only thing to note is that in the upper basin the basin boundary comes very close to the stream. You will need to zoom in on this region in order to avoid conflicts with the snapping tolerance.


Advanced Feature Objects 6-3

2. Choose the Stream feature arc type

3. Select OK

4. Create the main channel from the outlet of the watershed to the outlet point for the two upper basins. Begin by clicking near enough to the boundary arc at the outlet so that it snaps to it and end by clicking on the basin junction point.

5. Create the two branches of the lower basin by clicking on a point near the stream arc just created and double-clicking at the most upstream point of the branches in the image.

NOTE: As you create new vertices on stream arcs you should always do so from downstream to upstream.

6. Choose the Zoom tool

7. Zoom in on the region shown in Figure 6-1

Figure 6-1: Junction of Main Channel in Aspen Grove Watershed.


9. Create the initial portion of each stream by clicking on the junction point (intersection of red boundary lines in the image) and going as far upstream as is possible on the zoomed image. End by double-clicking.

You needed to zoom in order to avoid conflicts with the auto-snapping feature. However, if you click too close to an existing arc, you will get a message that the stream is illegal and you will need to try again.

You can end the stream at one location and then continue defining after zooming out by beginning at the point where you left off.


10. Select Display | View | Previous View

11. Finish defining each branch. Begin the branch by clicking near the point you left off with and ending by double-clicking at the terminal point of the stream.

In order to define separate basins at the junction point you will need to convert the node at the junction to an outlet node.


13. Select the junction point in the center of the watershed corresponding to the intersection of the streams and the sub-basin boundary arcs that you just created.


15. Set the attribute to Drainage outlet

16. Select OK

6.2.3 Building Polygons At this point the watershed boundaries are only arcs. In order for them to become polygons you must create the polygon topology.

1. Right-click on the Drainage coverage and select Build Polygon

2. Select OK when asked whether to use all the arcs to build the polygon (WMS excludes the stream arcs when building polygons).

3. Choose the Select Feature Polygon tool , double click on each basin polygon, and change the type to Drainage Boundary

6.2.4 Updating Geometric Parameters 1. Right-click on the Drainage coverage in the Project Explorer and

select Display Options on the pop-up menu

2. Select Map Data and turn on the Color fill polygons option

3. Select OK

In order to transfer the basin area and stream lengths and to compute them in appropriate units for hydrologic modeling, you need to compute the basin data. This will make it possible to use the polygon area in any of the hydrologic modeling interfaces.


4. Right-click on the Drainage coverage in the Project Explorer and select Compute Basin Data. This command computes areas, perimeters, and centroids for each of the sub-basins and assigns these values to the hydrologic modeling tree

5. In the Units dialog, select the Current Coordinates button

6. Make sure the Horizontal and Vertical units are Meters (the base units were UTM meters)

7. Select OK

8. Set the Basin Areas units to Square miles

9. Set the Distances units to Feet

10. Select OK to compute the sub-basin data

6.3 More Basin Delineation Now that you have the basics of digitizing a watershed from a topographic map and developing the correct topology for the watershed, you can try it again without the “burned” in lines on the image or the step by step outline.

6.3.1 Single Basin Delineation For the first part of this exercise you will delineate the entire watershed as a single basin.




4. Open “uppertrailmt.jpg”

You should have a portion of a scanned topographic map that has already been georeferenced. You should now delineate the watershed as a single basin, including the streams as indicated by the blue lines. Your final watershed should look similar to Figure 6-2 with an area of about 1.5 square miles. Step by step procedures will not be given this time, but you can refer back to previous sections for help and to the Figure 6-2. The following are a list of things you will want to remember:


5. Start by digitizing the streams and remember to make sure the feature arc attribute type is set to stream and that you digitized from downstream to upstream.

6. Digitize the boundary with arcs that are of type generic

7. Build polygons once you have created the arcs that form the boundary

8. Compute the basin data when you are done and make sure that the model units are meters

Figure 6-2 Delineated Upper Trail Mountain Watershed as a single basin.

6.3.2 Adding Sub-basins Once you have successfully digitized the watershed as a single basin, add two interior outlets as indicated in Figure 6-3 and digitize the sub-basin boundaries. Note in Figure 6-3 that the sub basin on the left side is defined by converting the vertex just below the junction of the stream to an outlet, thus treating that branch as a single basin, whereas the outlet for the right sub basins is placed on


the node that defines the junction of the streams, thus creating a separate basin for each upstream branch. Some important considerations are:

1. For the left side basin you will need to convert a vertex to a node

2. Be sure to change the attribute of the node defining the outlets to type outlet

3. Digitize the sub-basin boundaries with generic arcs and rebuild the basin polygons when you are done

4. Compute basin data

Figure 6-3 Delineated Upper Trail Mountain Watershed with sub basins.

Outlet at junction

Outlet below junction


6.4 Feature Objects from CAD Data You may have CAD data available (or shape files which would follow a similar process). DWG and DXF data can be automatically converted to feature objects in WMS.



3. Ensure that you are in the Map module


5. Open “af.dwg”

6. Select CAD | CAD -> Feature Objects

The dialog that opens shows a check mark for each layer that will be converted to feature objects. We will convert all layers and accept the default coverage type (which should be Drainage) and name (which should be CAD layers).

7. Select OK

8. Select OK to accept the coverage type and name

9. Select CAD | Display Options

10. Toggle off the check box at the top labeled Display CAD data

11. Select OK

Because these lines were created in AutoCAD, we cannot be sure that the streams were created using the WMS conventions for direction (and in most cases they will not be). In order to fix any such problems you can use the Reorder Streams command. By selecting the most downstream node in a stream network and invoking the Reorder Streams command, you tell WMS to ensure that all arcs are ordered downstream to upstream from the selected point.


13. Right-click on the left-most node in the interior of the basin (the left-most node on the portion that forms a network inside of the arcs forming a boundary) and select Reorder Streams on the pop-up menu.

14. Choose the Select Feature Line Branch tool


15. Select the arc attached to the left-most node (the node that was just used to reorder streams)


17. Select the Stream type and select OK

Each stream now flows the proper direction, toward the one drainage outlet at the left of the stream network. This outlet needs to be snapped to the basin boundary.


19. Right-click on the drainage outlet and select Clean on the pop-up menu.

20. Make sure Snap selected nodes is checked

21. Select OK

22. Choose the node on the basin boundary closest to the drainage outlet

23. Right-click on the CAD layers coverage and select Build Polygon

24. Select OK

This set of streams and basins is now properly ordered and connected and is ready to be used for hydrologic analysis.

6.5 Conclusion In this exercise you should have learned how to do the following:

1. Use feature object drainage coverages for watershed delineation

2. Assign appropriate feature object attributes

watershed modeling system - aquaveowmstutorials.aquaveo.com/tutor84_vol_i.pdf · 1-2 wms tutorials...

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