Read data from SDTS raster/DEM data set
[Z, R] = sdtsdemread(filename)
[Z, R] = sdtsdemread(filename) reads data from an SDTS DEM data set. Z is a matrix containing the elevation values. R is a referencing matrix (see makerefmat). NaNs are assigned to elements of Z corresponding to null data values or fill data values in the cell module.
filename can be the name of the SDTS catalog directory file (*CATD.DDF) or the name of any of the other files in the data set. filename can include the directory name; otherwise filename is searched for in the current directory and the MATLAB® path. If any of the files specified in the catalog directory are missing, sdtsdemread fails.
Elevation values can be imported with sdtsdemread from DEMs that use the SPRE Raster Profile (in use since January, 2001) as well as from older SDTS DEM data sets. Under this profile, elevations can be encoded either as 32-bit floating-point numbers (when their units are "decimal meters"), or as 16-bit integers (when units are "feet" or "meters"). The output class from sdtsdemread for both types of elevation encoding is double.
Note For details on locating map data for download over the Internet, see the following documentation at the MathWorks Web site: Finding Geospatial Data.