gensky result different from that in, Axel's tutorial

Hi Ji Zhang

> So, Which output is the correct one? What might causes the
> differences?

The Radiance Tutorial must be about ten years old now. I keep updating it, fixing small typos and inconsistencies, but have not felt the need to reflect the recent changes to gensky's turbidity.

Both, CIE clear and overcast are extremes that are fairly unlikely to occur in reality. As Greg said, you really need to feed in measurements, and also have a good guess at the turbidity if you are concerned about accuracy. If you can supply diffuse and direct irradiation, you might want to use gendaylit instead.

Axel

Just a side-note: the turbidity factor is _only_ used by gensky to estimate the zenith luminance. If the horizontal irradiance or zenith radiance is given using -B or -b (respectively), turbidity is ignored.

Cheers,
-Greg

ยทยทยท

From: Axel Jacobs <[email protected]>
Date: June 23, 2010 8:27:12 AM PDT

Hi Ji Zhang

> So, Which output is the correct one? What might causes the
> differences?

The Radiance Tutorial must be about ten years old now. I keep updating it, fixing small typos and inconsistencies, but have not felt the need to reflect the recent changes to gensky's turbidity.

Both, CIE clear and overcast are extremes that are fairly unlikely to occur in reality. As Greg said, you really need to feed in measurements, and also have a good guess at the turbidity if you are concerned about accuracy. If you can supply diffuse and direct irradiation, you might want to use gendaylit instead.

Axel