question on the Solar Energy on Building Envelopes tool

[yaron1000]

question on the Solar Energy on Building Envelopes tool
how can I get the facade wall of buildings data with a code/gis
i know the info is in the Energyyearwall.txt
am trying to know how much Energy gets the facade wall on the polygon in the city
and have a lot of polygons
thank you very much for the help
and the

[biglimp]

We know that the format of Energyyearwall.txt could be improved and we are working on an update. There is no simple way to do this but here is what I would have done:

Run a Python code in the QGIS script editor looking something like this:
from osgeo import gdal
import numpy as np
from osgeo.gdalconst import GDT_Float32

gdal_data= gdal.Open(string_variable_specifying_filepath_to_the_dem_used_in_SEBE)
grid_array = gdal_data.ReadAsArray().astype(np.float)
newraster = grid_array * 0.0
walldata = np.loadtxt(string_variable_specifying_path_to_Energyyearwall.txt, skiprows = 1)
for i in range(0, walldata.shape[0]):
newraster[walldata[i, 0] -1, walldata[i, 1] -1] = np.sum(walldata[i, 2:]

# save raster
rows = gdal_data.RasterYSize
cols = gdal_data.RasterXSize
outDs = gdal.GetDriverByName("GTiff").Create(string_variable_specifying_path_to_new_raster, cols, rows, int(1), GDT_Float32)
outBand = outDs.GetRasterBand(1)
outBand.WriteArray(newraster, 0, 0)
outBand.FlushCache()
outBand.SetNoDataValue(-9999)
outDs.SetGeoTransform(gdal_data.GetGeoTransform())
outDs.SetProjection(gdal_data.GetProjection())

The code is not tested and will probably not work the first time (I always mess up rows and columns etc.) But what I do is to create an empty matrix with the same size as the DSM used and fill those numbers with the sum of radiation on a wall pixel and then save as a raster geotiff. Then you need to find a way to relate wall pixels to a specific building using e.g. a vector dataset and zonal statistics.

[yaron-michael]

thank you very much for the help