How to make a logical mask using a shape file?

I am using following MATLAB code to create logical mask.

 % Create a logical mask
    [Z,R] = readgeoraster(img_file.name);
    disp(R);
    [lat,lon] = geographicGrid(R);
    [Lon, Lat] = meshgrid(lon, lat);
    logical_mask = reshape(isinterior(polygon, Lon(:), Lat(:)), size(Lon));

It is giving following erros

Incorrect number or types of inputs or outputs for function geographicGrid.

Error in ds_indices_caf (line 57)

[lat,lon] = geographicGrid(R);

I request to kindly suggest me how to do it correctly.

Dava

Answer 1

[Image Analyst]

You have to define lat and lon as vectors before you use them in meshgrid to get the full matrices Lat and Lon as outputs.

[Image Analyst]

OK, you edited the code to fix the missing definitions of lat and lon, but this is what we get

% Create a logical mask
[lat,lon] = geographicGrid(img_file.name);

Unable to resolve the name 'img_file.name'.

[Lon, Lat] = meshgrid(lon, lat);
logical_mask = reshape(isinterior(polygon, Lon(:), Lat(:)), size(Lon)); 

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[DGM]

geographicGrid() doesn't accept a filename as an input argument.

[Devendra]

I have attached the data (image file and shape file) in Data.zip. Test.m is the matlab code. I request you to please have a look on it and suggest me how to make it run successfuly.

Thanks a lot for your kind cooperation.

Deva

[Image Analyst]

It looks like it probably requires the Mapping Toolbox, which I do not have. Does it?

help geographicGrid

--- help for map.rasterref.GeographicCellsReference/geographicGrid ---

  geographicGrid - Geographic coordinates of raster elements
 
    [LAT,LON] = geographicGrid(R) returns the locations of
    raster elements in geographic coordinates as 2-D arrays,
    LAT and LON. When R is a GeographicCellsReference object,
    the locations are cell centers. When R is a
    GeographicPostingsReference object, the locations are
    posting points. The location of raster element (i,j) is
    (LAT(i,j), LON(i,j)). The values of size(LAT) and size(LON)
    both equal the RasterSize property of R.
 
    [LAT,LON] = geographicGrid(R,gridOption), where gridOption
    is 'gridvectors', returns LAT and LON as row vectors. The
    location of raster element (i,j) is (LAT(i), LON(j)). The
    value of [length(LAT) length(LON)] equals the RasterSize
    property of R. The default for gridOption is 'fullgrid'.
    geographicGrid(R,'fullgrid') is equivalent to
    geographicGrid(R).
  
    Example
    -------
    R = georefpostings([0 30],[-20 20],[4 5])
    [lat,lon] = geographicGrid(R)
    [lat,lon] = geographicGrid(R,"gridvectors")

    Documentation for map.rasterref.GeographicCellsReference/geographicGrid
       doc map.rasterref.GeographicCellsReference/geographicGrid

[Devendra]

I have installed Mapping Toolbox but it still gives the same errors

Unrecognized function or variable 'geographicGrid'.

Error in ds_indices_caf (line 57)

[lat,lon] = geographicGrid(R);

Deva

[Stephen23]

@Devendra: do you have a valid license for that toolbox?

[Devendra]

I have installed trial version of Matlab 2024a.

Deva

[Image Analyst]

I believe during the trial period you get free telephone help. Call them and work through it with an actual live person. I can't help you because I do not have that toolbox.