Mapping files include vector files for displaying polygons or points, and raster terrain files. Vector data can be loaded into HEC-MetVue, for visualization and basin average computations, as shapefiles. Shapefiles in and of themselves do not contain enough information to draw maps intelligently. For example, suppose a shapefile that has twenty Polygon definitions. Nothing within the shapefile specification informs us what these polygons represent. The polygons could represent lake surfaces, basin outlines, or a political district. It is useful to relate this polygon line to an attribute type so that it could be displayed as a double width green line or a dotted blue line. Point values, such as a rainfall gage location can be defined in a shapefile. But, again, nothing in the shapefile specification defines what this point represents or even a name to give it. Custom specifications must be defined that are in addition to the shapefile specifications in order to supply enough information to make use of the spatial features.
Terrain can be loaded into HEC-MetVue, for visualizing elevation via a TIF file. A Terrain node was added to house the TIF file. The terrain layer combines a raster and hill shade layer together to draw the terrain elevation with coloring and shading to represent elevation changes. The hill shade layer can be turned off in the Layer Settings tab if the user wants to view just the raster data. It is recommended that the display coordinate-system matches the coordinate-system of the selected TIF for the fastest and most accurate rendering.