I am trying to take a land surface temperature raster layer and “burn” polygons into it, so that they show up in the LST layer. I know there are methods for burning streams/rivers into raster DEMs, but these would be lines, and I am not sure about polygons.
I have the following LST layer with micro-green space polygons overlaid:
As you can see, when I remove the green space polygons, they are not detected or at all noticeable in the underlying LST layer, as the resolution of the LST data (calculated from Landsat 8 bands 10 and 11) was just too low to pick them up:
I want to take my green space polygons and “burn” them into the raster layer so that they become a part of the raster layer, and would now exist as cooler temperature pixels in the shape of my green space polygons. My polygons have no temperature attribute. The lowest temperature I have in my LST layer is 8 degrees Celsius. So I would want to have my raster layer have the shapes of my polygons as just areas of 8 degrees Celsius throughout the whole shape.
Can this easily be done in QGIS? I think I need to “rasterize” my polygons first, but I am confused about how to actually imprint them onto my raster layer.