Merge Grid Files

Function

This command creates a grid file by merging together two existing grid files, grid1 and grid2. The current grid is grid1 and the program will prompt for a second grid. These two grids must overlap with the same location and resolution. The inclusion and exclusion perimeters apply to grid2 such that the merged grid will consist of grid2 cells within the inclusion perimeters and outside the exclusion perimeters and grid1 cells everywhere else. The result is stored in the current grid.

No elevations are calculated on grid cells that extend beyond the extent of the data. Extrapolation can be used to calculate elevations for the grid cells that are beyond the data limits. The prompt Extrapolate grid to full grid size? shows when there are grid cells with no elevation in a grid (.GRD) file. Extrapolation fills in all the grid cells. The method to extrapolate uses a safe calculation that tends average out or level the extrapolated values. So extrapolated grid areas are not as accurate as grid areas within the limits of the data.

Prompts

Select Source Grid 1 File Dialog
Enter a name for the existing grid1 file. The default directory is the Carlson data directory.
Extrapolate grid to full grid size [Yes/<No>]? press Enter
Select Source Grid 2 File Dialog
Enter a name for the existing grid2 file.
Select the Inclusion perimeter polylines or ENTER for none. press Enter
Select the Exclusion perimeter polylines or ENTER for none. press Enter
Merged Grid File to Write Dialog
Enter a name for the new grid file.

Pulldown Menu Location: Surface
Keyboard Command: mergegrd
Prerequisite: Two grid (.GRD) files
File Name: \lsp\makegrid.arx