I'm using QGIS to work with raster data. I have a raster dataset of a country where each grid cell is assigned a number 1-100. However, the raster is in the format of a rectangle based on the extent of the file, so all of the cells outside of the borders of the country are assigned a 0. I cannot figure out how to create a GeoTIFF that excludes these cells that have a value less than 1. Any ideas? Thanks!