UHI+UWG Questions

[AlexKDo]

Hello again.. I am trying to run UHI Feature now and I am having some trouble..
So I did:

3.16. Urban Land Cover: Land Cover Fraction (Grid)
3.18. Urban Land Cover: Land Cover Reclassifier
3.19. Urban Morphology: Morphometric Calculator (Grid)

and I am having trouble with:

3.14. Urban Heat Island: UWG Prepare
4.10. Urban Heat Island: Urban Weather Generator

In UWG Prepare I should use the vector polygon grid that depicts the modelling area(s). This should be the same polygon layer that was used in Urban Weather Generator. But in Generator I should have the parth that contains .uwg-files generated by UWGPrepare.But I dont have it since I cannot seccessfully run Prepare.

extra Question: Grid files should be the same vector polygon grid or 1 for 3.16 and a new one for 3.19?

[biglimp]

You should do LandCoverReclassifier before you use the LandCoverFraction (Grid). The Grid you use should be the same for all tools in this process.

[AlexKDo]

So I did in this order and I did a first run but I had many errors+ when I tried UWG Analyzer I pressed Generate many times but nothing happened. So this is an example of error. I think something went wrong with the previous steps I did.. This is a random PrtSc.

[biglimp]

So, open the Python Console in QGIS, rerun UWG and report the error displayed fro one grid.

[AlexKDo]

so I did this to see the error and I cancelled the generator. This is the msg

Traceback error message while caclulation grid: 168
Traceback (most recent call last):
File "C:\Users/alexk/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\UMEP-processing-main\processor\uwg_algorithm.py", line 224, in processAlgorithm
model.generate()
File "C:\OSGeo4W\apps\Python39\lib\site-packages\uwg\uwg.py", line 1176, in generate
self._compute_input()
File "C:\OSGeo4W\apps\Python39\lib\site-packages\uwg\uwg.py", line 1671, in _compute_input
road_veg_coverage = self.vegcover / (1 - self.blddensity)
ZeroDivisionError: float division by zero

[biglimp]

So it looks like you have building density = 1 (nothing but buildings) which the model so not accept. Check you input for this grid and see if that is true.

[AlexKDo]

Yes, from LandCoverage Grid I have 1 and from Morphology I have 1 too. And this is the same for all grids that are buildings.

[biglimp]

Then you must have something wrong when you calculated fractions and morphology. Can you attach two sceendumps from one grid in QGIS, one showing land cover and the other one showing your DSM.

[AlexKDo]

I have them in the same grid layer. This is an example

[biglimp]

No, I want to see your raster data in your map canvas.

[AlexKDo]

[biglimp]

Thanks.
UWG is a local scale model so your grids are too small. I recommend using grids that are at least 200x200 meters. Even larger are recommended (400x400).

[AlexKDo]

Ok. Thank you very much!