Maps SDK for Qt display Geotiff with transparent background

Question

I am evaluating the ArcGIS Maps SDK for Qt to see if it fits our needs. To test it, I have done a small project for a map and scene viewer.  In both viewers, I import a GeoTIF (data/orofotomosaic.tif in the project) which is an RBGA image. However, the image is shown with with background instead of transparency (in the attached image there's also another GeoTIF displayed in green scale which is not relevant to this post):

The way I create that raster layer is:

Esri::ArcGISRuntime::Raster *raster = new 
Esri::ArcGISRuntime::Raster("path/to/photomosaic.tif", parent);
Esri::ArcGISRuntime::RasterLayer *raster_layer = new Esri::ArcGISRuntime::RasterLayer(raster, parent);

How can I keep the transparent background of the imported TIF file?

JamesBallard1 · Answer

> But it is rendered black!

@imbachb I believe this is another symptom of the same problem with supporting raster transparency with certain formats. Someone else had reported a similar finding where transparency was rendered as solid back here: https://community.esri.com/t5/qt-maps-sdk-questions/geotiff-with-transparency-nodata/m-p/1262976#M4864

JamesBallard1 · Answer

Hi @TroyFoster. No progress on "included ranges" I'm afraid.

JamesBallard1 · Answer

Hi @apalomer-iqua.

I can confirm that we don't support transparency with GeoTiff format. Possibly it's something we could support in the future, but it's not in our plans for the moment.

There are a few options. PNG should work with transparency, but I don't know if it's possible to switch formats of your raster data.

Another possibility is to use a raster mask function:

https://developers.arcgis.com/qt/layers/add-raster-data/#mask

A notable downside to this is the mask function would only allow you define a pixel as ON or OFF, it will not give you transparency, i.e. percentage of "opaqueness". In your case that may be ok.