Once a blank DEM has been setup (Create DEM >> Setup Blank DEM), elevations can be assigned by sampling an external raster DEM or Triangular Irregular Network (TIN).
| Note: | Only DEM pixels that have no data will be sampled from the external DEM. This allows for several DEMs to be sampled to complete the CatchmentSIM DEM. For example, a highly detailed DEM with some missing data could first be sampled followed by a lower resolution DEM to fill in the blanks. Alternatively, the blanks can be filled in by using the interpolate DEM function (Create DEM >> Interpolation Tools >> Interpolate Remaining Areas) |
Sampling a raster DEM can be useful because it allows the DEM information to be preserved while changing the DEM resolution and projection. When this function is selected you may be asked to provide the projection of the source DEM (unless it is inherent eg., SRTM DEMs are always in lat/long). If you decline to select the DEM projection when prompted, the DEM will be assumed to be in the same projection as the project.
| Note: | If you have several DEMs that you wish to sample, or a number of DEMs that cover different regions of the CatchmentSIM DEM, these can be group selected using Ctrl and Shift buttons or dragging a rectangle in the Open File dialog box. |
