Daylight factor: CIE uniform sky

chris · June 17, 2023, 4:47pm

The distribution of light across the overcast sky does not change much with the illuminance used to derive it. Granted, it can be a little different if the illuminance is a whole order of magnitude but you can see this for yourself with the components:

overcast_skies.gh (32.2 KB)

So the illuminance used for the overcast sky isn’t really going to have much of an effect but, if you really must know the illuminance used in the Daylight Factor recipe, you can see that it is 10,000 lux and this is even written into the filename of the sky:

github.com

pollination/daylight-factor/blob/master/pollination/daylight_factor/_prepare_folder.py#L59


      
              'recipe will simply unzip the file and simulate it as-is.',
              extensions=['json', 'hbjson', 'pkl', 'hbpkl', 'zip'],
              alias=hbjson_model_grid_input
          )
          
          
@task(template=GenSkyWithCertainIllum)
          def generate_sky(self):
              return [
                  {
                      'from': GenSkyWithCertainIllum()._outputs.sky,
                      'to': 'resources/100000_lux.sky'
                  }
              ]
          
          
@task(template=CreateRadianceFolderGrid, annotations={'main_task': True})
          def create_rad_folder(self, input_model=model, grid_filter=grid_filter):
              """Translate the input model to a radiance folder."""
              return [
                  {
                      'from': CreateRadianceFolderGrid()._outputs.model_folder,
                      'to': 'model'

In any event, I personally would not worry about the difference and I loose much more sleep thinking about the radiance parameters that people use. But, if you’re really concerned about it, then just use a Point-In-Time Grid recipe with the HB Certain Illuminance sky.