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matlabmappinggeotiff

reading and displaying USGS NED DEM

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? Here is a download link for the DEM http://snowserver.colorado.edu/pub/fromDominik/NED_10340081.zip Thanks PS I crossposted this at http://www.mathworks.com/matlabcentral/answers/38255-display-usgs-dem-using-geotiffread-and-mapshow

Solution

  • I finally figured it out. geotiffread gives a matrix type 'single' but mapshow defaults to show an image which only accepts type 'double' (and some others). So the solution here is to either:

    A=double(A);

    or

    mapshow(A,R,'DisplayType','surface');