Working in QGIS 2.8.1 Wien.
I have a raster file with three classes:
"No data" for tiles outside of the country of interest's bounds "0" for tiles that correspond to roads "1" for all other tiles.
I want to use proximity (raster distance) to create a new raster layer of distance to roads for all tiles... but want to maintain the "no data" tiles as "no data".
However, when I run proximity, it ignores any calls to the "No data = " option and assigns distance values to all "no data" tiles. I can't type any string input into the "No data = " option, and am unsure of how to keep my "no data" cells.
How do I do this?