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EEXXPPLLOORRIINNGG MMOOOORREEAA DDAATTAA WWIITTHH QQUUAANNTTUUMM GGIISS In this exercise, you will be using an open-source FREE GIS software, called Quantum GIS, or QGIS. You can download QGIS at http://qgis.org/ for free, and install it on both PCs and Macs. While QGIS contains less geoprocessing and spatial analysis tools than ArcGIS, it is an excellent program for exploring data and making maps, and best of all, it is FREE and EASY TO USE! In this exercise, you will be working with the Moorea datasets, some of which were downloaded from the Internet, and others which have been created from past research at Moorea. All data is in Universal Transverse Mercator (UTM) Zone 6 projection, and WGS 84 datum.

ETM_satellite.tif - Landsat Enhanced Thematic Mapper (ETM) satellite image. 30-meter resolution. Source: Moorea_topo_bw.tif - Digital topographical map, in black & white. Source unknown. Moorea_topo_color.tif - Digital topographical map, in color. Source unknown. haapiti_photo.tif - Black & white aerial photograph of a portion (Haapiti area) of Moorea. Source unknown. papetoai_photo.tif - Black & white aerial photograph of a portion (Papetoai area) of Moorea. Source unknown.

Airport.shp – Airport location and runway. Source unknown. Channel_markers.shp – Channel marker locations. Source unknown. hotel.shp – Hotel location, points. Source unknown. hotel_bndy.shp – Hotel property boundary. Source unknown. island_outline.shp – Outline of the Island of Moorea. Source unknown. mooring2002.shp – Locations of moorings, 2002. Source unknown. mpa1999.shp – Marine Protection Areas, 1999. Source unknown. mpa2001.shp - Marine Protection Areas, 2001. Source unknown. mpa2002.shp - Marine Protection Areas, 2002. Source unknown. Reefs.shp – Reef areas. Source unknown. Road.shp – Main island road. Source unknown. towns.shp – Town locations. Source unknown.

111 Mulford Hall, College of Natural Resources, UC Berkeley (510) 643-4539

http://qgis.org/

Exploring Moorea Data with Quantum GIS Geospatial Innovation Facility

1. Start QGIS, by double clicking Quantum GIS (1.8) from your home screen.

When the program opens, you can see that there is a Map area, Table of contents, Overview map area, and Toolbars. Click OK to close the QGIS tip.

2. Find the “Manage Layers” toolbar, which looks like this:

This is where you add data. There is a SEPARATE BUTTON for VECTOR, RASTER, GEODATABASE, and

WEB MAPPING SERVICE data. You can also access each of these tools under the “Layer” menu.

3. Click on the “Add a Raster Layer” button:

The Open dialog opens. Set “Files of type” to GeoTIFF.

Navigate to C:\Workspace\Moorea\Moorea, and add the following layers:

ETM_satellite.tif

Haapti_photo.tif

moorea_topo_bw.tif

moorea_topo_color.tif

papetoai_photo.tif

Map area Table of

contents

Toolbars


4. Experiment with different viewing options. Clicking the x next to the feature names in the table of contents will turn the layer on and off in the viewer. Moving the layer names in the table of contents will also change the order in

which the layers are arranged in the viewer.

5. Click on the “Add a Vector Layer” button:

Click the “Browse” button. Navigate to C:\Workspace\Moorea\Moorea, and add all the shapefiles layers that

appear. Click Open twice to see the layers in your map.

6. Change the order (or turn off certain layers) until your map looks similar to the one below.

7. Change the symbology of your layers to appropriate symbols, by right-clicking and choosing “Properties.” For

example, right-click on Road and choose Properties.


8. In the Layer Properties window for the Road layer, under the

Style tab, choose from the “saved styles” at the bottom of the dialog window.

* Note that if your window does not look like the one in the image to the right, you may need to click the “New Symbology” button in

the top right corner. To fine tune your symbology selection, try adjusting the color and

width. Click “apply” to see changes on you map.

9. Under the General tab, change the Display name

to “Main Moorea Road”

This is how you can change the display name in the Table of Contents.

When you are finished setting the Layer Properties for

the Road layer, click OK.

9. Open the Layer Properties for the island_outline layer. Under the Style tab, click the button to

access more style options. Change the Fill Style to be No Brush, and the Border width to 1.5. Click OK.


10. Open the Layer Properties for the Reef layer, and under the Style tab, change the Transparency slider to be

50%.

Explore the Map Navigation Toolbar

Hover over each tool in the Map Navigation toolbar to see what they do:

1. Zooming & Panning

Experiment with zooming in and out, using the zoom buttons. With the zoom in/out tools, you can either draw a box around the area you want to zoom in/out on, or you can click once.

Use the pan tool to move the map around while staying at the same scale, or zoom level. There are many ways to move around your data – use the tools that you like best!

a. Click on Full Extent to zoom all the way out to all layers.

b. Click once on a single layer to “select it” in the Layer List, and then click on Zoom to Layer: This will zoom your map to the extent of that layer only.

2. Identifying

The identify tool can be a good way to browse the attribute information behind

the geospatial data. Attributes are data that correspond to a spatial location, whether

it is a point, line, or polygon shape.

a. First click once on the towns layer to select it in the Layer List.

b. Using the Identify tool, click on a town polygon. You can read the information about the feature that you clicked, in this case, the town’s name. QGIS also has the


ability to automatically derive the area of selected polygon features, as seen in the results window.

c. Explore other layers, such as the reefs and hotels, by identifying features.

Be sure to select each layer in the Layer List to select it, before identifying it!

3. Measuring

The measure tool is very good for performing fast and easy distance measurements.

a. Click on the measure tool.

A message might come up that looks like the one here. If it does, then you’ll have to set the Projection.

b. Go to the Settings menu, then to Project Properties. Under the Coordinate Reference System (CRS) tab, set the Projection to Projected

Coordinate Systems > WGS 84 / UTM zone 6S.

If you can’t find it in the list, you can search for its ID by clicking “EPSG ID” and searching for

“32706”.

c. Click once on the left side (west end) of the island… and then on

the right side (east end). Each left click will start a new segment. Right click to end the measurement.

Try measuring some features of interest.

d. You can also measure areas using the Measure Area tool from the

drop down:


4. Exploring the Attribute Tables

a. Select the Channel_markers layer in the Layer List, and click on the “Open Attribute Table” icon: A window called Attributes table - Channel_markesr opens. This is the attribute table for your

Channel_markers layer.

5. Build a query

From the attribute table, you can click on Advanced search (see circled above). The Search query builder window comes up.

a. Double-click on ID0.

b. Click on LIKE, because you are going to search for all markers that may include the word ‘pylon’ c. Click on the “Sample” button, to view a sample of the values in that column field.

d. Double-click ‘pylon - Port’. See below for illustration.

e. Click “Test” to make sure the syntax is correct. Then click OK.


This finds THREE MATCHES that include the word ‘pylon - port’ in the values of that column field. These are automatically selected, and are highlighted in yellow on the map.

6. Selecting features

The select features by rectangle tool can help you find out the attributes of two or more features in a

layer at once. a. Close the attribute table if it is still open, and click on the drop down arrow for the select tool. Choose the Select Rectangle Tool

b. Click on the Channel_markers layer in the Layer List/Table of contents to select it. c. Draw a box around several channel markers on the map.

e. Click on the “Open Attribute Table” button, and the Channel_markers attribute table opens. All the points that were selected are now highlighted.

Explore other tools

The two toolbars you have not used yet include: The DIGITIZING toolbar:

The Digitizing toolbar is used to create new data (“digitize”) data on your map, or edit existing data. You have the ability to create/revise both spatial data (where a point, line, or polygon data exists), and the

attribute/tabular data (the attribute data behind the spatial data).


PLUGINS:

The Plugins manager (Plugins | Manage Plugins) gives you access to many tools that are extensions of QGIS’s core functionality

Some recommended plugins include:

Add Delimited Text Layer

o Convert a list of xy coordinates to points

GdalTools o Convert between different file types

Interpolation plugin

o Create a raster surface based on values within a vector point layer

Raster Terrain Analysis Tool

o Create Slope, Hillshade, and Aspect raster layers

from a DEM.

Spatial Query Plugin

o Make spatial queries to vector data

fTools

o Adds a suite of geoprocessing tools under the “Vector” heading in the main applications drop

down menus.

.

Export your map view by going to the File menu Save as Image... and change the “File Type” to JPG.

Create a map layout by going to File New Print Composer… This opens the print composer where you can design a map with scalebar, legend, etc.

Save your map by going to the File menu Save Project, or by clicking on the Save icon:

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