1. Import raster data. Use the File | Open... command to import GIS data files such as Shapefiles or raster files. Alternatively, drag and drop the file into the Graphics Window in GMS. 2. Import TIN elevation (optional). Use the File | Open... command to import TIN files. Alternatively, drag and drop the file into the Graphics Window in GMS. Note: TINs can also be generated in GMS using scatter point elevation data.