| | 1 | 1. At this stage it is assumed you have created a GRASS project in UTM projection and imported the DEM for your area in that project. |
| | 2 | |
| | 3 | 2. Create a new GRASS project in the same database as your UTM project. |
| | 4 | 1. Let's assume the name is AREA_LL and mapset PERMANENT. |
| | 5 | 2. The projection needs to be Lat/Lon, the area boundaries are not important. |
| | 6 | 3. The resolution can also by any for now. |
| | 7 | 4. The datum should wgs84 and parameter should be 1. |
| | 8 | |
| | 9 | 2. Once you have entered the AREA_LL project, import the elevation spheroid as below; |
| | 10 | "r.in.ascii input=~arsf/dems/geoid-spheroid/ww15mgh.grd output=wwgsg" |
| | 11 | |
| | 12 | 3. Now you can exist AREA_LL, go back to your UTM project |
| | 13 | 1. Import/Re-project the elevation spheroid as below; |
| | 14 | "r.proj -n input=wwgsg location=AREA_LL mapset=PERMANENT output=wwgsgUTM" |
| | 15 | 2. Now elevated the DEM by adding the spheroid; |
| | 16 | "r.mapcalculator amap=yourDEMmap bmap=wwgsgUTM formula=A+B outfile=yourelevatedDEMmap help=-" |
| | 17 | |
| | 18 | 4. Process is complete! |
| | 19 | |