I have several topographic maps with oddly-shaped geography that extends into the margins.
Here is one example:
When I select Transparent Margins and convert these images to UTM, the marginal geography is cropped out.
Is it possible to selectively include these areas in the cropped UTM?
The initial layout of the mask is taken from the so-called neat-line which is part of the meta data in the GeoPDF file. When TransDEM shows the mask as a rectangle (before it is rendered with the yellowish background), you can modify it. With the context menu you can add the necessary new points and shape the mask as you need it by dragging the points around.