Preset for shadow bias for VraySun

[3d-laboratory]

I don´t understand why shadow bias for VraySun has a preset of 0,2m. In the nature our sun has a preset for the shadow bias of 0,000m Is there a possibility to edit this preset? And can me tell anybody why it is set to 0,2m in Vray? Is there a cause?

[nikoleta.garkova]

Hi 3d-laboratory

Yes, you can change the value as you see fit. To read more about Shadow bias and get some examples, you can visit: https://docs.chaosgroup.com/display/VMAX/VRaySun#VRaySun-Sampling
Last but not least, being set by default to a particular value is after our devs and QAs have made extensive tests and have concluded that this would be the most effective and accurate respective value.

Hope this helps.

[3d-laboratory]

Thank you for the quick answer. As I work for a long time in this field I sometimes wonder about the high values of this preset. Also mentalray had a preset of 0,25 m. To illustrate what happens with bias of 0,2 and 0,0 see the picture below. If you have small objekts on a facade lit by VRaySun in a sharp angle shadows are absolutely absent with a bias of 0,2m.

[matanov]

The issue in this case comes from your units setup. The default value is "0,2 <units>" and in most cases people work in units that fit their scene type. For example for single buildings or interiors - centimeters/inches so that bias is almost not visible while protecting them from shading problems. We can think of keeping it constantly to something small regardless of the units setup, but that might create problems for people working with large scenes (f.e. few kilometers long).

[3d-laboratory]

I thought somthing like this allready, but my system units are meters and my diplay units as well. And in the bias slot I can read "0,2m". So it seemed to be the same scale for me. And so also the results are. If bias is 0,2m the ojbects shadow begins 0,2m behind it. It is no problem for me, but it is one thing that I have to have in my head inserting a VRaySun to the scene.

[Morne]

nevermind...