GeoServer flips the WMS v1.3.0 image when applying a heatmap style on a layer with a CRS EPSG:4326

Question

I was trying to apply the following heatmap style to an unprojected layer (EPSG:4326) in GeoServer.

*{
  
  transform: vec:Heatmap(weightAttr:1, radiusPixels:40
    
    , pixelsPerCell:5, 
    
    outputBBOX:env('wms_bbox'), outputWidth:env('wms_width'), outputHeight:env('wms_height'));
  
  raster-channels: auto;
  raster-color-map-type: ramp;
  raster-color-map:color-map-entry(#008000, 0.005,0)
                   color-map-entry(#4B53BC, 0.05, 0.3)
                   color-map-entry(#003348, 0.1, 0.4)
                   color-map-entry(#0099EE, 0.2, 0.5)
                   color-map-entry(#D51606, 0.4, 0.6)
                   color-map-entry(#FF9C33, 0.6, 0.7)
                   color-map-entry(#FFCD42, 0.7, 0.8);
  
}

The image displays correct when using WMS v1.1.1 but on v1.3.0, the WMS image gets flipped.

I have replicated the behavior on a default GeoServer layer: Manhattan (NY) points of interest.

Points:

WMS v1.1.1:

WMS v1.3.0

---

However, projected layers such as sf:bugsites seems to display correctly.

I believe this is not intended behavior but that the best solution for now is to work with projected data or stick with WMS v 1.1.1?

Answer 1

This is intended behaviour, and is required for WMS 1.3.0. Its documented as https://docs.geoserver.org/latest/en/user/services/wms/basics.html#axis-ordering

I would stick with WMS 1.1 unless you need something in 1.3.0. Using a different projection or adapting to WMS 1.3.0 are also valid solutions.