[Radiance-general] Gendaymtx and ground

[Ruggiero Guida]

Hi,

I am trying to understand how to use the results from gendaymtx when my
ground is not flat but it is represented by a generic surface.

The first patch generated by gendaymyx is for the ground and it has the
units of W/sr/m2. It has a constant value for each direction below the
horizon.

If I consider a surface dA placed 1 m above the ground (assumed flat for
now) and pointing downwards, I would measure:

g x 2 x Pi [W/m2]

This is assuming that I have used the typical descriptions for the ground
geometry as an hemisphere below the horizon and that there are no
obstructions as these would change the light that is reflected from the
ground.

Is this correct?

If it is, then in order to consider grounds with generic surfaces I should
ignore the first value in gendaymtx and use the actual geometry for the
ground.

Does this make sense?

Thanks
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