[GRASS-user] Change elevation value for entire DEM raster cell

[Rich Shepard]

   I need to change the elevation value for a specific DEM raster cell. The
first approach did not work as intended and I need to learn how to correctly do
this.

   Originally, I used a vector point map to identify the coordinates (which
are many times finer than the 1m x 1m cell size), then ran v.in.ascii using
those x and y coordinates while adding a new z coordinate. The result was
rasterized, but that one point did not change the values for all other
points within the cell.

   Can I do this with the GUI in the map display window with the raster
digitizer?

   Locating the specific cell the way I've tried doing this is quite
inaccurate. When I display the raster map overlaid with the vector map
containing the point of interest (which is on the corner of 4 raster cells),
I have not figure out how to get the information for the raster cell because
it's the vector map on the top of the stack.

   So, two questions:

   1. How can I identify specific 1m x 1m raster map cells based on the
location of a vector map point? Changing opacity of the topmost vector map
does not allow me to query the underlying raster map. With the raster map on
top of the z-stack I cannot accurately identify the raster cells that need
to have their elevations changed.

   2. Once I have the proper information to specify specific cells, r.mapcalc
allows me to change the elevation value of a point, but how to change the
elevation for the entire cell?

Looking forward to learning new skills,

Rich