exercise 5 - spatial analysis and model builder

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GIS EXERCISES

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  • 5-1

    Spatial Analysis and Model Builder

    ArcGIS Spatial Analyst provides a broad range of powerful spatial modeling and analysis

    capabilities. You can create, query, map, and analyze cell-based raster data; perform integrated

    raster/vector analysis; derive new information from existing data; query information across

    multiple data layers; and fully integrate cell-based raster data with traditional vector data

    sources.

    With ArcGIS Spatial Analyst, some examples of the things you can accomplish include:

    Derive new information from existing data.

    Apply Spatial Analyst tools to create useful information from your source data.

    Some examples of things you can do include deriving distance from points, polylines,

    or polygons; calculating population density from measured quantities at certain

    points; reclassifying existing data into suitability classes; or creating slope, aspect, or

    hillshade outputs from elevation data.

    Find suitable locations.

  • 5-2

    Find areas that are the most suitable for particular objectives (for example, siting a

    new building or analyzing high-risk areas for flooding or landslides) by combining

    layers of information.

    For example, based on a set of input criteria defining that areas of vacant land with

    the least steep terrain that are nearest to roads would be most suitable for a

    development project, the following graphic shows the most suitable locations in

    green, medium suitability in yellow, and the least suitable locations in brown.

    Perform distance and cost-of-travel analyses.

    Create Euclidean distance surfaces to understand the straight-line distance from one

    location to another, or create cost-weighted distance surfaces to understand the cost

    of getting from one location to another based on a set of input criteria you specify.

    You can calculate the distance in a straight line from any location (cell) to the nearest

    source, or you can calculate the cost of getting from any location to the nearest source.

  • 5-3

    Identify the best path between locations.

    Identify the best path or optimum corridors for roads, pipelines, or animal migration,

    factoring in economic, environmental, and other criteria.

    The shortest path might not be the least-costly path, and there might be several

    alternative corridors that could be taken.

    Perform statistical analysis based on the local environment, small

    neighborhoods, or predetermined zones.

    Perform calculations on a per-cell basis between multiple rasters, such as calculating

    the mean crop yield over a 10-year period. Study a neighborhood by calculating, for

    example, the variety of species contained within it. Determine the mean value in each

    zone, such as the mean elevation per forest zone.

  • 5-4

    Interpolate data values for a study area based on samples.

    Measures a phenomenon at strategically dispersed sample locations and predict

    values for all other locations by interpolating data values. Create continuous raster

    surfaces from elevation, pollution, or noise sample points. With a set of point spot

    heights and vector contour data, create a hydrologically correct elevation surface.

    Clean up a variety of data for further analysis or display.

    Clean up raster datasets that contain data that is either erroneous, irrelevant to the

    analysis at hand, or more detailed than you need.

  • 5-5

    What is ModelBuilder?

    ModelBuilder is an application you use to create, edit, and manage models. Models are

    workflows that string together sequences of geoprocessing tools, feeding the output of one tool

    into another tool as input. ModelBuilder can also be thought of as a visual programming

    language for building workflows.

    While ModelBuilder is very useful for constructing and executing simple workflows, it also

    provides advanced methods for extending ArcGIS functionality by allowing you to create and

    share your models as tool.

    ModelBuilder can even be used to integrate ArcGIS with other applications.

    The benefits of ModelBuilder can be summarized as follows:

    ModelBuilder is an easy-to-use application for creating and running workflows

    containing a sequence of tools.

    You can create your own tools with ModelBuilder. Tools you create with ModelBuilder

    can be used in Python scripting and other models.

    ModelBuilder, along with scripting, is a way for you to integrate ArcGIS with other

    applications.

  • 5-6

    GIS Laboratory Exercise 5a Exploring the ArcToolbox Objectives: In this exercise, you will:

    - Be able to orient yourself with ArcToolbox - Locate some of the ArcInfo tools

    Exploring the Toolbox To be an effective GIS desktop application it should have almost all the necessary tools for processing. In ESRI ArcInfo 10, the necessary geoprocessing tools are made available to users. It might be for 2D or 3D processing requirements. For this part of the exercise, we will locate ArcToolbox. ArcToolbox can be accessed through ArcMap or ArcCatalog.

    o Run ArcCatalog.

    o On ArcCatalog toolbar, move your mouse over the ArcCatalog icon . A description

    appears that signify the name of the button which is ArcToolbox window.

    o Click on the ArcToolbox icon to open the ArcToolbox window. ArcToolbox window can

    also be accessed by clicking Geoprocessing menu then ArcToolbox (as shown below).

    A dockable window will now appear bearing the name ArcToolbox. You can dock this window to

    any area within ArcCatalog.

    1. Observe how ArcToolbox organized the tools. What did you observed?

    ________________________________________________________________________

    ________________________________________________________________________

    ________________________________________________________________________

    o From the ArcToolbox window, expand Conversion Tools and expand To Geodatabase.

    Right-click on Cad To Geodatabase and select Help from the pop-up menu.

    2. State the capability and usage for this tool. (Hint: Base your answer from the Summary.)

    _______________________________________________________________________

    o Close the ArcGIS 10 Help window.

  • 5-7

    o Put your attention to the Catalog Tree docked window (this is by default located on the

    left side of ArcCatalog).

    The Catalog Tree dockable window shows the Folder Connections, Toolboxes, and other

    hierarchical representation of ArcInfos components. This of course would depend on your

    settings using the ArcCatalog Options.

    o Click on the Customize menu and select ArcCatalog Options.

    o If necessary, select the General tab. From the list on the General tab, make sure that

    only Folder Connections (always shown) and Toolboxes are checked. If necessary,

    uncheck Hide file extensions and click OK.

    Creating Personalized Toolbox

    As you have observed, only the items you checked on the ArcCatalog Options General tab is

    now available. Hiding the items that are not necessary for now will be more helpful in

    organizing the ArcCatalog Tree.

    o Using the ArcCatalog Tree expand Toolboxes. Using the knowledge of the path you

    learned earlier, locate CAD to Geodatabase.

    o From your Folder Connections, connect to your home directory (e.g. Z:\).

    o On the ArcCatalog Tree, right-click on the home directory you have added, select New

    and click on Toolbox.

    o Check that on the center pane the tab is set to Contents.

    On the center pane, observe that Toolbox.tbx with a type of Toolbox has been created. Using

    this feature, you will be able to organize your own set of tools that you will need for your GIS

    processes.

    o Rename Toolbox.tbx into myToolbox.tbx. (Hint: Right-click on Toolbox.tbx and click

    Rename.)

    o Again using either the ArcToolbox window or the Catalog Tree, right-click on the Cad to

    Geodatabase tool and click Copy.

    o Right-click on your myToolbox.tbx toolbox container and select Paste.

  • 5-8

    Observe that the tool is now copied to your myToolbox container. This would give you the

    comfort of locating your needed tools. Still your myToolbox can contain another type of

    container inside which is call a Toolset. A Toolset is like a folder that can contain the actual

    tools. Using the Toolset will allow you to segregate your tools according to their uses or by any

    categories of your preference.

    o Using the Catalog Tree right-click on your myToolbox, select New and click Toolset.

    o Rename the Toolset into Conversion Tools.

    o Right-click on the CAD to Geodatabase tool located inside your myToolbox and choose

    Copy from the popup menu.

    o Right-click on your own Conversion Tools toolset and select Paste.

    An error message appeared telling us that the copying of the tool was unsuccessful (as shown

    below).

    This is because we already have the existing tool within our myToolbox. Therefore, we have to

    remove first the tool and make a copy once again, but this time specifying the toolset as the

    destination.

    o Right-click on the CAD to Geodatabase tool inside your myToolbox and choose Delete.

    Click Yes on the Confirm Delete window.

    o Once again locate CAD to Geodatabase tool from the ArcToolbox/System Toolboxes,

    right-click on it and paste it to your Conversion Tools toolset within your myToolbox.

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