Source product should be map projected - Multitemporal Compositing

Microwave Toolbox
1

Hello,

I am working on a study of an area in the German low mountain range. Therefore I am trying to minimize the influence of the terrain on the Sentinel-1 images. I am following this preprocessing workflow: Forests | Free Full-Text | Potential of Sentinel-1 Data for Spatially and Temporally High-Resolution Detection of Drought Affected Forest Stands

First I calibrate my Sentinel-1 GRD files to β() and then perform Teraiin flattening to γ(). Then I create a stack. Then I create a stack. I then want to reduce the speckling with a multitemporal composite. When I run the Multitemporal Compositing operator, I get the error message:

Error: Source product shoul be map projected.

Where does this error come from? Why does it work in the mentioned study?

Just like in the study, I use Sentinel-1 GRD and the steps:

  1. Calibrate to β()
  2. TerranFlattening to γ()
  3. CreateStack
  4. MultiTemporal-Composite

After applying the Range-Doppler Terrain correction it works, but the speckle filtering (in my case a multitemporal speckle filtering by compositing) should be done before.

Thanks for any tips