Control feature rendering order

If enabled, Control feature rendering order allows you to define the order in which attributes will be rendered. The rendering order is set using expressions that define subsets of attributes for a rendering group, whether than subset should render in ascending or descending order, and whether NULL values should render first or last.

The following screenshot shows two expressions and their rendering options. In this case, the features that were selected in row 1 will render on top of the features that were selected in row 2, and within each row, they will be rendered in either ascending or descending order. The NULL values will be rendered first or last:

For our example, let's make sure that the larger proportional circles are rendered below smaller circles so that the smaller circles will not be hidden behind the larger circles. The following screenshot shows default rendering on the left (larger circles rendered on top of smaller circles) and controlled rendering on the right (smaller circles on top of larger circles):

To achieve this rendering of larger circles on the bottom, we simply set the attribute controlling the size of the circles to render in Descending order, as shown in the following screenshot:

Layer rendering can really improve the look of your map. So, experiment with the layer rendering methods to find the ones that work best for your overlays.