Creating an SRTM service with the Visualize Elevation process

Shuttle Radar Topography Mission (SRTM) data includes digital elevation models of the earth's surface, with measurements derived from the return signals received from two radar antennae on a spacecraft. Each data file covers a one-degree-of-latitude by one-degree-of-longitude block of earth's surface. You can use the Visualize Elevation process to display this elevation data using various methods of visualization.

The following procedures involve creating a new image service definition, adding SRTM data, then generating a shaded relief using the Visualize Elevation process.

Learn about the Visualize Elevation process

Creating an SRTM image service definition

步骤：

1. Open ArcMap.
2. Click the Image Service drop-down arrow on the Image Service Definition Editor toolbar, point to Advanced, then click New Service Definition.

   The Image Service definition dialog box is displayed.

3. Type the path and name in the Service definition text box, or click the browse button to navigate to the location and provide a name.
4. Click the Spatial reference browse button and choose a spatial reference file for either a geographic or projected coordinate system.
5. Click the Service type drop-down arrow and click Elevation.

   The default values for Number of bands, Pixel type, Bit depth, and Color space for the Elevation service type appear. You can change these values.

6. Click OK to create the new image service definition.

   The new image service definition is added to the table of contents as a customized group layer.

7. Click the Image Service drop-down arrow on the Image Service Definition Editor toolbar, point to Advanced, then click Add Raster Dataset.

   The Select Raster Type dialog box is displayed.

8. Double-click Elevation.
9. Click SRTM-3.
10. Click OK.

    The Add SRTM-3 Data dialog box is displayed.

11. Select a file or folder that contains raw SRTM files with .hgt extensions.
12. Click OK.

    The raster datasets are added to the image service definition, and footprints are displayed as green rectangles.

Applying the Visualize Elevation process

步骤：

1. Click the Image Service Properties button on the Image Service Definition Editor toolbar.

   The Image Service Properties dialog box is displayed.

2. Click the Service Processes node in the left of the dialog box.
3. Add the Visualize Elevation process.

   Learn how to apply a process on an image service definition

4. Click the Edit button to change the required process parameters.

   The General tab is displayed by default.

5. Click the Visualized As drop-down arrow and click Shaded Relief.

   Keep the default parameters for Altitude (45.0), Azimuth (315.0), and Z-Factor (1.0).

6. Click the Symbology Source tab.
7. Click the Symbology source drop-down arrow and click Generated On-the-fly.
8. Click the Range source drop-down arrow and click Computed from AOI.
9. Click the Computation method drop-down arrow and click Standard Deviation.
10. Click the Symbology Properties tab.
11. Change the values for First color and Last color if desired.

    These colors are used to create the color ramp.

12. Click OK.
13. Click OK to close the Image Service Properties dialog box.
14. Click the Image Service drop-down arrow on the Image Service Definition Editor toolbar, point to Advanced, then click Build.

    The Build Options dialog box is displayed.

15. Make sure Compute output pixel properties is checked.
16. Click OK.

Creating service overviews and compiling

步骤：

1. Click the Image Service drop-down arrow on the Image Service Definition Editor toolbar, point to Advanced, point to Optimize Service, point to Overviews, then click Define.
2. Click the Format drop-down arrow and click JPEG 2000.

   Since the data is stored as 32-bit, you should keep it in its original format in the service overviews to preserve the pixel values. To do this, the format can be JPEG 2000, or the format can be TIFF with Compression method set to Uncompressed.

3. Click OK.
4. Click OK on the message box letting you know the service overviews have been defined.
5. Click the Image Service drop-down arrow on the Image Service Definition Editor toolbar, point to Advanced, then click Build.
6. Make sure Generate derived images is checked.

   By default, Compile service is checked. Checking Generate derived images operation creates the service overviews you've defined.

7. Click OK.

   The image service is first compiled, then the service overviews are generated. Once this is complete, you can preview and publish the image service.