Wh would you use a shadow bias higher than 0.0?

[markus_s_cg]

I've noticed some weird shadows in some scenes I've been rendering lately, for example when using a scene bought from evermotion, and I discovered that for some reason the v-ray sun had a shadow bias of a few maybe 0.2 cm, and in other cases more (maybe due to rescaling a scene. This is creating a weird effect where the shadow was further away from the casting object. Why would you need a shadow bias higher than 0.0?

[^Lele^]

0.0 is bad as you may get disappearing shadows altogether.
It's not as bad, however, as the state of the shadow bias section of the docs as it is right now, so sorry about that.

In general, Shadow Bias is a dark art, as it depends on distances and scene sizes.
A low, non-zero value is generally fine (type 0.02 in the box, provided your units are sensible, ofc, like Cm, or mm, and not meters or kilometers.).

[Buck]

in centimeters in Maya, I usually set all of my lights to .001 if I'm doing shots of anything medium range and especially for close up shots. For wide shots or shots not close up it usually doesn't seem to make a difference.

I've tried putting it to zero and I don't remember having any issues, but I've been warned that there could potentially be issues. So I leave it at .001 usually

[markus_s_cg]

Thanks for the feedback! I tried setting it to 0.0 and didn?t have any problems. Maybe there is something going on under the hood that converts it to a very low value, like 0.001 without telling the user (if 0.0 is not a good value)? Anyways, thanks for the info!

[Art48]

0.0 is bad as you may get disappearing shadows altogether.
It's not as bad, however, as the state of the shadow bias section of the docs as it is right now, so sorry about that.

In general, Shadow Bias is a dark art, as it depends on distances and scene sizes.
A low, non-zero value is generally fine (type 0.02 in the box, provided your units are sensible, ofc, like Cm, or mm, and not meters or kilometers.).

On that note, the default bias for the VRaySun is 0.2. That is huge. I have run into issues with this (forgetting that this was 0.2 and not the default 0.02 as everywhere else) often times, and I have to remember to set it correctly and I can't use the defaults here.
It would be really good if the VRaySun defaults to 0.01 or 0.02 instead of 0.2

[tricky]

This is one of those annoying 'defaults' that needs more intelligence. Our scenes are always (well, 99% of the time) in meters, and if we don't forget to change the value (we typically always use 0.0 and it hasn't ever given us a problem) shadows on 'normal' sized objects (curbs, bris soleil etc) do not work properly. Why can't these defaults have a bit more intelligence so that they respect the scene units?

It's like with the default physical camera setup: why oh why would anyone want those default settings???

[Richard7666]

This is one of those annoying 'defaults' that needs more intelligence. Our scenes are always (well, 99% of the time) in meters, and if we don't forget to change the value (we typically always use 0.0 and it hasn't ever given us a problem) shadows on 'normal' sized objects (curbs, bris soleil etc) do not work properly. Why can't these defaults have a bit more intelligence so that they respect the scene units?

It's like with the default physical camera setup: why oh why would anyone want those default settings???

this is something I've never really thought about, do you have any examples of the difference you could post, showing where you've had it misbehave?

[tricky]

Next time it crops up I will post it.

[LudvikKoutny]

I hope this value will soon be removed and handled internally. I don't think shadow bias is something an end user should come in contact with.

[^Lele^]

I hope this value will soon be removed and handled internally. I don't think shadow bias is something an end user should come in contact with.

I'm all ears for suggestions, personally.