Recently I got the SRTM DEM from Cgiar,which based on WGS84/EGM96.
and I merged the tiles to one tiff file. I want to get the WGS84 ellipsoidal heights.
According the steps from the Arcgis Help 10.2 "Converting from orthometric to ellipsoidal heights",I do the whole steps,but I found the tif file was not changed,the height was the orthometric height based on EGM96 geoid. I Want one tif format DEM with ellipsoidal heights based on WGS84 ellipsoid.
I don't know where the problem is?
The steps I followed :
Create a file geodatabase
- Click the Catalog button on the Standard toolbar. This opens the Catalog window. In the Location text box, type C:\arcgis\ArcTutor\Raster and press ENTER.
- Right-click the Raster folder and click New > Folder. Name the folder Exercises.
- Right-click the Exercises folder and click New > File Geodatabase. Rename the new file geodatabase ImageGDB.
Set the default geodatabase
Right-click the ImageGDB geodatabase in the Catalog window and click Make Default Geodatabase.
Create a new mosaic dataset
- Right-click ImageGDB in the Catalog window and click New > Mosaic Dataset. Type HMA in the Mosaic Dataset Name text box.
- Click the Coordinate System browse button . Expand Projected Coordinate Systems >, choose wgs84 world mercator.prj, then click OK. Click OK on the Create Mosaic Dataset tool dialog box.
Add rasters to the mosaic dataset
- Right-click the SRTM mosaic dataset in the Catalog window and click Add Rasters. This opens the Add Rasters To Mosaic Dataset tool.In the Raster Type list, choose Raster Dataset.
- Click the drop-down arrow and click Workspace.
- Click the Input browse button. Navigate to C:\arcgis\ArcTutor\Raster\Data\SRTM_tif and click Add.
- Check Update Overviews.
- Click OK to run the tool.
Add the Arithmetic function
- Open the Catalog Window and navigate to the mosaic dataset. Right-click the mosaic dataset and click Properties.Click the Functions tab.
- Right-click the Mosaic Function and click Insert > Arithmetic Function.
Input Raster 1 is identified as the current contents of the mosaic dataset and will not be changed. Click the Input Raster 2 browse button and navigate to the \pedata\geoid folder in the ArcGIS install location.Choose the WGS84.img and click Add.
- Click the Operation drop-down arrow and click Plus.
- Click OK to close the Raster Functions Properties dialog box.
- Click OK to close the Mosaic Dataset Properties dialog box.