Display USGS DEM using geotiffread and mapshow

Hi, I'm trying to use USGS DEMs in MATLAB but after reading it in with geotiffread, mapshow produces an error. Based on the documentation, I tried

[A, R] = geotiffread('NED_10340081')
figure
mapshow(A, R);

but I get

Error using mapshow
Expected input number 1, I or X or RGB, to be one of these types:

    uint8, uint16, double, logical

Instead its type was single.

Error in validateMapRasterData>parseImageInputs (line 109)
validateattributes(A, {'uint8', 'uint16', 'double', 'logical'}, ...

Error in validateMapRasterData>validateImageComponent (line 93)
        [A, R] = parseImageInputs(mapfcnname, dataArgs{:}, cmap, rules );

Error in validateMapRasterData (line 27)
        [Z, SpatialRef] =  validateImageComponent(mapfcnname, ...

Error in maprastershow (line 127)
[Z, SpatialRef, displayType, HGpairs] = ...

Error in mapshow (line 231)
h = showFcn(varargin{:});

My matrix A is of type single...is that the problem? and how do I fix this? Thanks

[Em]

I encounter this same issue using 2013b. My file is from the Global Land Survey DEM (<http://glcf.umd.edu/data/glsdem/)>. I read the file using:

[B, R] = geotiffread('/home/mrd20/matlab/geo/data/GLSDEM_n040e060');

After applying the fix above to B (convert to double), I then find mapshow objecting to 'R' which has the type:

map.rasterref.GeographicCellsReference

where as mapshow expects either a 3-by-2 referencing matrix or a scalar map raster reference object.

I find that geoshow does not list an error condition, but creates a 'blank' plot having the correct lat/lon info on the axes.

I've been working through geospatial webinars, but working with non-WMD resources is not given attention there.

Cheers, ~ Em

Answer 1

[Dominik]

geotiffread results in a type 'single' but mapshow defaults to a 'image' that can only accept 'double' (and some other formations not including 'single'). Either A=double(A) or mapshow(A,R,'DisplayType','surface')

[Em]

I encounter this same issue using 2013b. My file is from the Global Land Survey DEM (<http://glcf.umd.edu/data/glsdem/)>. I read the file using:

[B, R] = geotiffread('/home/mrd20/matlab/geo/data/GLSDEM_n040e060');

After applying the fix above to B (convert to double), I then find mapshow objecting to 'R' which has the type:

map.rasterref.GeographicCellsReference

where as mapshow expects either a 3-by-2 referencing matrix or a scalar map raster reference object.

I find that geoshow does not list an error condition, but creates a 'blank' plot having the correct lat/lon info on the axes.

I've been working through geospatial webinars, but working with non-WMD resources is not given attention there.

Answer 2

[Wanda Crupa]

You can also show geotiff images using the imagesc(geotiff) command.However, this does not display them using geographic coordinates as needed for a map, but is great for cheking any image processing of raster data.

Example:

[geotiff1, R] = geotiffread('my_geotiff.tiff');
imagesc(geotiff1);

[Eslam Wafdy]

How to adjust the coordinates to be in WGS84?

[MaHa]

Same question