In an earlier post I wrote how I created a mash-up map with MapTiler. There is an option in MapTiler to set transparency for a color, but this didn’t work for me at the time. I therefore created a small script to convert the background color to transparent and to process all PNG tiles generated by MapTiler using the PNGNQ utility.
I am working on a new online map and this time setting the background color to transparent in MapTiler works like a charm. I wonder whether this is because the function only works on indexed images and for some reason I did not get indexed images after exporting the raster file last time.
Like last time, I exported my GRASS raster layer as a georeferenced tiff file using the r.out.tiff function. The NODATA / background color was white. So after opening the tiff file in MapTiler, I simply marked white as transparent (second screen of the MapTiler wizard, see image below).
The rest of the steps are fairly obvious, just follow the steps of the MapTiler wizard.