You can add as many types of map layers as needed. In HEC-RTS Version 3.1.1, HEC-RTS can transform coordinates "on-the-fly" as long as a map layer's coordinate system is defined properly. For example, for an Arc shapefile there is an associated projection (.prj) file. The projection file contains the mathematical formulas that relate to the spherical coordinates on the globe to flat, planar coordinates.
Map layers are added from the Maps menu in any of the HEC-RTS modules. When a map layer is added to the watershed, HEC-RTS reads the coordinates of points, lines, and polygons on the map layer and resets the geographic extents of the watershed equal to the smallest rectangle that will contain all objects in the map layer. When adding more than one map layer, you must ensure that each map layer is projected in the same coordinate system (). For example, if an Arc shapefile (.shp) is added that displays the major streams in a watershed area, the geographic extents will change according to the projection of that shapefile. If the shapefile is projected in State Plane Coordinates in feet, HEC-RTS will set the geographic extents accordingly, and the units of the stream alignment will be in feet.
To add map layers:
- From the HEC-RTS main window, from the Maps menu, click Map Layers, the Map Layers dialog will open (Figure 1).
- From the Layers menu, click Add Maps, the Select Map to Add browser (Figure 2) will open.
- Select the desired map layer format from the Files of type list. Select the filename, and click Open. The Select Map to Add browser will close (Figure 2). The selected map layer will display in the map window, and in the Map Layers dialog (Figure 1), the map layer will display under the Map Layers tree.
When enabled, the Create Copy checkbox (default) on the Select Map to Add browser (Figure 2) will copy the selected map layer to the active watershed's directory structure under the maps folder.