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
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,
[Z, R] = sdtsdemread('9129CATD.ddf'); mapshow(Z,R,'DisplayType','contour')
Elevation values can be imported with
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
For details on locating map data for download over the Internet, see the following documentation at the MathWorks Web site: Finding Geospatial Data.