Displaying negative values in IDW+marker layer

[GeorgA]

Hi,
I'm using Orchestra Cities - Map Panel 1.4.4 (installed in Grafana 9.1.7).

I want to display a IDW heatmap for reception strength values (RSSI). These are usually negative (e.g. -90dBm), the legend has to show some custom threshold colors (e.g. -100dBm = red, -75dBm= orange, -50dBm = green). Over the heatmap I want to add a marker layer with the exact locations and values of the measurement with the same colors, the marker data source is the same query as for the IDW layer.

Unfortunately I cannot make the IDW layer to honor the negative value range for the threshold colors. The "min" weight value must be at least 0. So I end up with a "doubled" threshold table (-100 to -50 for the marker layer, 0 to eg. 50 for the IDW layer with weight 0 to 50). Works, but the double threshold setup is tedious and the legend also shows the confusing positive values for the IDW layer.

Is there a way to display negative values in the IDW and marker layers with only one color setup?