exelisvis.com / Docs Center / Using ENVI / Topographic Tools / Convert Vector Topographic Maps into Raster DEMs Topographic data is frequently available in both vector and raster formats. While each format has its advantages, ENVI offers several tools for extracting additional information from raster digital elevation model (DEM) data. For example, you can use raster DEMs to do the following: Use Convert Contours to DEM to triangulate a raster grid for the DEM from the vector records’ nodes. It is recommended that the output pixel size be set no smaller than the approximate sampling distance of the vector nodes. If the output pixel size differs significantly from the node sampling distance, the vector contour lines are automatically made more dense in an attempt to reduce interpolation artifacts. All vector records contained in the file are used unless their corresponding elevation attribute value falls outside the valid elevation range you specified. The vector data must be an ENVI vector format (.evf) file. The .evf file must contain an attribute that defines the elevation of each vector contour line. If the vector topography is in an external format file (such as a shapefile), open the data in ENVI and the import routine prompts you to convert the file into an .evf. Source.