Issue in merging Tree Generator and existing cDSM (created using NDVI and DEM)

[QGISUser2413]

Dear community,

I am running a scenario analysis using UMEP Solweig. I wish to implement a greening scenario, and so, as guided in the tutorial, I have created a shapefile with trees. Now, while using the tree generator tool, I am adding everything correctly, but it is only generating the cDSM for the newly added trees and not merging it with the existing cDSM.
Due to a lack of appropriate tree information,
I have used NDVI and DSM to generate the cDSM, and cross-validated it by visualizing it with a Google Earth image.
Please help. I am sharing my CDSM and the tree shapefile for reference.

New Tree Shape file:
BoTreesScenario_09072025.zip

Original cDSM:
Bo_CDSM_AlignedClip07072025.zip

Generated cDSM_scenario:
Bo_CDSM_Scenario1_09072025.zip

[biglimp]

You forgot one layer. You need to provide information where buildings are located, either through a building grid OR a DEM and a DSM layer for us to try this.

[QGISUser2413]

Here is the TIFF of the building grids attached, generated by the model.

buildings.zip

[biglimp]

Yes, you have identified a bug in the code. We will fix this but it might take some time due to Holidays etc. In the mean time, I suggest that you simply add your two CDSMs manually via the RasterCalculator (old CDSM + new CDSM).

[QGISUser2413]

Thank you for the reply. I have merged the two CDSMs manually.

[biglimp]

Hi again. I tried to find an error in the code but was unsuccessful. When I try on the test datasets that we have for Gothenburg (https://github.com/Urban-Meteorology-Reading/Urban-Meteorology-Reading.github.io/blob/master/other%20files/Goteborg_SWEREF99_1200.zip), I am able to merge the two CDSMs.

Could you try on your system, if you are able to join using the datasets in link above?

[biglimp]

@QGISUser2413 , any update on this?

[QGISUser2413]

Apologies for the late reply. I didn't manage to try the simulation with your data, as I merged the files using Python, and got busy with further work. I believe it may be working with your Gothernberg dataset, but the issue here is why it is not working with my layers? Can you please help me find the possible reason behind this?

Thank you!

[biglimp]

As I cannot locate any error, it is hard to find the reason for this. Things that could cause issue might be the format of your rasters, e.g. CRS, NoData values etc. Have a look at the Gothenburg data and compare with yours to see if you can find any apparent differences.