12/8/2023 0 Comments Arcpy define raster projectionFor your Output Coordinate System, click on and choose WGS 1984 UTM Zone 43N. Select an appropriate location for your output raster. To do this, go to ArcToolbox in the main navigation bar: Data Management Tools->Projection and Transformation->Raster->Project Raster. To avoid this, you need to project your DEM using the Project Raster tool. Using these DEMs to create a Hillshade or a Slope map (something you will do in the next section) with the default values can yield incorrect results. When we download DEMs in raster format, the spatial reference is usually a geographic coordinate system (versus a projected coordinate system). If the vertical units are not corrected to the horizontal units, the results of surface tools (e.g., Hillshade, Slope, etc.) will not be correct. It is the number of ground x,y units in one surface z unit. The z-factor is a conversion factor that adjusts the units of measure for the vertical (or elevation) units when they are different from the horizontal coordinates (x,y) units of the input surface. Before we move to the next section, you need to know about the z-factor.Is there an attribute table? Is the grid integer numbers or floating point (real numbers)? What is the current coordinate system?Ĭlose the Layer Properties dialog. In the Table of Contents, right click on your DEM file and choose Properties. Open the Coordinate System tab, and check that the Current coordinate system matches that of the DEM file. Right click on Layers, and select Properties. Why do you like to display your data this way? Think about what you would like to communicate to the viewer? You will include this map in your final PDF file.Ĭ. Then go to File->Export Map and save your map as tiff. Add your name (required) to the map ( Insert->Text). Click on Grids, and create a new grid (Graticule). To insert Grids, click on View and select Data Frame Properties. Using this menu, insert a title, legend and scale bar for your map. Then click on Insert in the main navigation bar. Which symbolizations of your DEM do you prefer? Ramp or # of classes? Click OK when you are happy with what you have.ī. Click on the View tab in the main navigation bar. If you are not happy with the results, try increasing the number of classes and see what happens.Ī. Click OK, and then Apply and look at the DEM as before. Make sure the number of classes is 5 and that the Method is Equal Interval. The histogram of the distribution of the elevation values is the central feature of the Classification dialog. It may not look good with only 5 classes! Click the Classify button in the upper right of the dialog. This will divide the values (elevations) of the DEM into a number of groups or bins, each of which can be assigned a different color. Click Apply and move the properties dialog aside so you can see what the DEM looks like in the selected map. Pick one you think will work better than the greyscale default. Try several of the color ramps to try to improve the visualization of the terrain. The default setting for grid data is Stretched. Choose Properties from the bottom of the menu, and go to the Symbology dialog. To do this, right click on your DEM file in the Table of Contents. You can change this setting in the Layer Properties dialog. Open Toolbox, go to Data Management Tool/Raster/Raster Properties/Build Raster Attribute Table. It should look like this:įirst, create a raster attribute table. Then, click on Add data button and navigate to your folder and click on Add. Your DEM will be displayed as a gray scale image with the lowest values black and the highest values white. Download the elevation data file nasa_srtm_v3.0_3arcsec_tajik_, safe it to the same folder and unzip the file. Choose File->Save and navigate to the folder on your USB stick you want to save it to and name the file “arc1_ex_XX” where XX is your initials. Begin with a new, blank document in ArcMap.
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