How to add a map created in QGIS to a Matlab plot

Question

I am generating a number of plots in Matlab. I want to overlay these over maps I have created in QGIS. I thought the best way would be to import the maps as a geotiff into Matlab and then overlay my plots over the image. I have saved the project as an image, generating a tiff and a tiffw file.

I got stuck trying to import and display the tiff and tiffw file in Matlab. I am working with QGIS 2.10.1 and Matlab R2012b.

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Here is what i have tried so far:

Matlab has a geotiffread() function to read geotiff files. Using this function to read the .tiff produces the following error.

Error using geotiffinfo>readinfo (line 259) The file 'GeoTest.tiff' does not contain any GeoTIFF Tags. Use the function IMFINFO to obtain information about the file.

I was able to import the .tiffw file into matlab using the code.

filename = 'GeoTest.tiff';
RGB = imread(filename);
worldFileName = getworldfilename(filename);
R = worldfileread(worldFileName, 'planar', size(RGB))

But still have to figure out how to put that into a figure together with my plot.

Answer 1

In QGIS, export the map as in image via 'save as image' in the file menu and choose 'tiff' as the file type. This will produce both a .tiff and a .tiffw file. The .tiffw file is known as a World File. As far as I can tell the .tiff file is not a GeoTiff file, or at least, Matlab does not recognise it as a GeoTiff file.

There seems to be an issue with the way QGIS generates its tiff files, to fix this do the following:

Open the file in an image processing program (I used ImageJ) and then save the file as a new tiff file.

In Matlab, use mapshow() to display the 'new' tiff file. Make sure the tiffw file is in the same directory.

mapshow('myMap.tiff')
ha = mapshow(X1,Y1,'DisplayType','point','Marker','s','MarkerEdgeColor','k')
hb = mapshow(X2,Y2,'DisplayType','point','Marker','o','MarkerEdgeColor','k')
legend([ha hb],'Stations', 'Assets');    
axis off