Is there a way in QGIS to prioritize the layering order overlapping polygons. I have a shapefile with numbers in the attribute table from 1-20. Each number is associated with its own polygon. I want to layer the polygons from highest number to lowest. I would like to colour fill them as well. And it's basically a contour map.
There is an option to activate the
Control feature rendering order under Symbology:
in which you can identify the rendering order based on a field:
However, since overlapping polygons are considered topologically incorrect, it is better to clean the contour polygon to get rid of overlappings. The solution is to use v.clean tool from
Processing toolbox -> GRASS GIS 7 commands -> Vector -> v.clean, and in cleaning tool use
Break. Please have a look at Cutting all polygons with each other - mega slicing answer which solve this issue with illustrations.