Digital maps (GIS layers) are referred to as map layers in HEC-RTS. When a map layer is included in a watershed, the software displays the map layer as GIS features, points, lines, and polygons. The map layer formats that HEC-RTS can display are listed in Table 1.

Table 1 Map Layer Formats Supported by HEC-RTS

Arc Shapefiles (.shp)

This file type is the native data structure for the ArcGIS® program. Shapefiles store non-topological geometry and attribute information for the spatial features of a data set in a particular format. Usually there are three component files associated with a shapefile: .dbf, .shp, and .shx. The .shp file contains the shapes (points, polylines, or polygons) that are displayed in the layer.

Each shape has a record in the .dbf file containing descriptive data called "attributes". The .shx file contains an index that links each shape to its record in the .dbf file. For more information on shapefiles, see the ESRI Shapefile Technical Description available here: http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf

AutoCAD® DXF (.dxf)

A Drawing Interchange File (.dxf) is created by a Computer-Aided Design (CAD) package, AutoCAD®. This format is a tagged-data representation of an AutoCad® drawing file. Tagged data refers to each data element being preceded by a group code. A group code is an integer indicating the type of data element. The file created is a vector-based graphic. The DXF format is commonly used for data exported from other CAD and GIS programs.

Raster Image

The raster image formats supported by HEC-RTS are: JPEG format (.jpg or .jpeg), Graphics Interchange Format (.gif), Portable Network Graphic (.png), bitmap (.bmp), and Multi-resolution Seamless Image Database (MrSID or .sid). This .img file should not be confused with the format for raster images used by the ERDAS Imagine image processing program. HEC-RTS cannot display files in the ERDAS Imagine .img format.

Virtual Format (.vrt)

The *.vrt format is a format driver for GDAL (Geospatial Data Abstraction Library) and allows for a virtual GDAL dataset to be composed of other GDAL datasets. The primary use of this format is to group together a series of grids that should be associated together. This file format allows multiple depth grids for the same event to create a mosaic single grid. Relative file paths are saved in an XML format, as well as a histogram describing the frequency of cell values across all grids within the *.vrt.

GeoTIFF (.tif)

A metadata standard which allows geo-referencing information to be embedded into a TIF (Tagged Image File Format) file. The added metadata could be map projection datums, coordinate systems, and any other information that will establish spatial references. A TIF file stores raster graphic images and data within a single file.

Mr SID (.sid)

The MrSID® (multi-resolution seamless image database) is a propriety geo-referenced image file format developed by LizzardTech® for use with. This format compresses large raster images files like aerial photographs or satellite imagery for easier viewing. Some MrSID images contain geo-referencing and positioning information and can be placed in the watershed (from the Map Layers dialog, from Layers, click Import Image(s)).

OpenStreetMap (.osm)

This is an XML file created in the OpenStreetMap (OSM) file format, which is used for saving street map information. This file is generated by HEC-RTS in the watershed's map folder and should not be placed or edited by the user.

USGS Digital Line Graph (.dlg)

U.S. Geological Survey (USGS) Digital Line Graphs (DLGs) are created from two sources using manual and automated digitizing methods. The two sources are aerial photographs or cartographic sources. DLG files are vector representations of the data. When HEC-RTS interacts with a .dlg file it automatically creates a .dlgbin file for use.

USGS DEM (.dem)

USGS publishes the file format USGS DEM. A raster file format, .dem files usually contain terrain elevations, but the file format can be used for representing any surface. The format allows for internal documentation of the coordinate system, date of publication, etc. These values are referenced horizontally either to a Universal Transverse Mercator (UTM) projection or to a geographic coordinate system.

SMRMP (.smrmp)

Segmented Multi-Resolution Multi-Parameter (SMRMP) file (HEC-FIA) created to operate gridded data (namely, digital terrain grids, inundation depth grids, and arrival time grids) more efficiently.

ASCII NetTIN (.net)

This is an ASCII file format used to represent a triangulated irregular network (TIN). TIN data are stored in a simple format that defines the nodes, edges, and triangles contained in the TIN. This format is common for transferring TIN data between software.