Matching Up Topo Maps in TransDEM

[activerail]

I've created several routes now with TransDEM. The only problem I've had is trying to match up multiple topo maps. Is there a way to "clip off" the white borders of the maps so that they can be lined up (patched together). I have had a off set of 20-30 meters in several cases.

[geophil]

Is there a way to "clip off" the white borders of the maps

Yes, there is.

For paper map scans you would normally start with "Crop Image Margins", but this often does not suffice.

The more complex clipper is called "Transparent Margins" and it works with as mask that you shape yourself. It starts with a rectangle but you drag the points and add more as you like to fit the edges of your map.

"Transparent Margins" can be set before and after georeferencing. If set afterwards, georeferencing information will not be lost!