Dimension of the solar radiation results

[hxTrans]

Hello, may I know the dimension of the solar radiation results. If my input is a DSM 1 arc-second, the solar radiation will be displayed in grids of 30m*30m. Is that correct？

[biglimp]

Depends on where you are on the globe. 1 arc-second is getting smaller as you travel north from the equator (30m at the equator). Change your CRS to a meter-based system e.g. UTM to see your pixel resolution.

[hxTrans]

Great! Could you provide some instructions or guidance on how to export the value of solar irradiance on the vertical facade in QGIS?
For example, can I subdivided the facade into patches and obtain the irradiance of the centroid of each patch?

[biglimp]

The format of the current output from the model is found here: https://umep-docs.readthedocs.io/en/latest/processor/Solar%20Radiation%20Solar%20Energy%20on%20Building%20Envelopes%20(SEBE).html#solar-radiation-solar-energy-on-building-envelopes-sebe

We are currently working with an update of the format. If you have any preferences of suitable format, please let us know and we will take it into consideration.

[hxTrans]

Hi biglimp,

Sorry for the late follow-up. I found the txt file containing the irradiance of building facades.

Is there any way that I can obtain the geolocation of each pixel on building facades according to the 'row' and 'column' ? I have read the paper of Lindberg, F. et all. The simulation is very accurate. Therefore, I would like to have the numeric results besides visualization.

Many thanks in advance!

[biglimp]

@nilswallenberg , didnt you just write some conversion between rows and columns to geographical coordinates?

[biglimp]

To recalculate to geographic coordinates you need to know the dimensions and pixel size from the original raster, e.g. your DSM. The calculations looks at below:

GT(0) x-coordinate of the upper-left corner of the upper-left pixel.
GT(1) w-e pixel resolution / pixel width.
GT(2) row rotation (typically zero).
GT(3) y-coordinate of the upper-left corner of the upper-left pixel.
GT(4) column rotation (typically zero).
GT(5) n-s pixel resolution / pixel height (negative value for a north-up image).

minx = gt[0]
maxy = gt[3]            
ywall = abs(rowwall - (maxy - gt[5]/2))
xwall = (colwall + (minx  - gt[1]/2))