Shadow blur artifact issue

[Mzigaib]

I am having problems with depth map shadows when I increase the shadow blur, even with the simplest scenes it happens mostly with plane surfaces like a ground.

I must be missing something.

Can someone help?

1st pic shadow Configs(No shadow blur):

Shadow Bias - 0.05

Shadow Quality - 1

Shadow Softness - 1

Shadow Blur - 0.0

Res - 512X512

pixel samples - 1X1

2nd pic shadow Configs(With Shadow Blur):

Shadow Bias - 0.05

Shadow Quality - 1

Shadow Softness - 1

Shadow Blur - 0.1

Res - 512X512

pixel samples - 1X1

Edited September 13, 2010 by Mzigaib

[LaidlawFX]

weird your image was hiding your settings in my firefox. now it's better.

Make sure you have Transparent Shadows checked(this turns deep shadow maps on), check Depth Map Motion Blur this does what it says esp for deep shadow maps, increase the resolution to at least 1k to 2k, then slowly increase Pixel samples up until you get your right quality- it is your quality control knobs once you get everything else set. Once you get the shadow correct and if your objects are not moving turn off Auto-generate Shadow Maps to cache it.

If you are using the spot light feature, uncheck Use cone Angle for field of view and your projection angle will be the width of your shadow map.

If you are using distant light your orthographic width will control you shadow map width.

[Mzigaib]

I've made some experiments to see what can really make influence on the result of the shadow, also I took in consideration the tips given on this forum.

[Mzigaib]

I noticed that you have to combine some settings to get rid of the artifacts, this was already said here but what settings or values or combination of both could interfere on the result of the shadow?

So I did some simple tests alternating some settings and I noticed that if you use shadow blur the need of a big quality settings makes a difference but you have to also increase the Bias settings, this way I could get rid of the artifacts, just increasing the quality settings made the artifacts go away but it darkened the surface I think because it just spreads the shadows the problem was just solved by increasing the Bias.

This was just a simple test, but I am sure that the scene scale can modify these conditions, maybe someone with more experience with that can add some more information.

Any observation would be welcome.

[LaidlawFX]

I noticed that you have to combine some settings to get rid of the artifacts, this was already said here but what settings or values or combination of both could interfere on the result of the shadow?

So I did some simple tests alternating some settings and I noticed that if you use shadow blur the need of a big quality settings makes a difference but you have to also increase the Bias settings, this way I could get rid of the artifacts, just increasing the quality settings made the artifacts go away but it darkened the surface I think because it just spreads the shadows the problem was just solved by increasing the Bias.

This was just a simple test, but I am sure that the scene scale can modify these conditions, maybe someone with more experience with that can add some more information.

Any observation would be welcome.

As you light and render more you are going to come across many types of artifacts and noise. The best thing to do is to read the documentation, and do simple test like you're doing until you run across enough stuff that you gain experience, or your good at wiggling all the setting real quickly to fix it. I didn't get the setting right from settings off the top of my head, but if you read up on bias it was a good one to play with before the other settings I mentioned.

From the docs - The bias when computing shadows from this light source. This is a small distance. If occluders are within this distance, they will not be considered shadowers. This is to prevent self-shadowing artifacts due to the limited resolution of depth map shadows. Note: Increase the bias value to obtain a nice shadow when working with a large scene. Try a shadow bias 5-10% of the scene scale to start.

[Mzigaib]

Thanks for the explanation, sometimes the solution is under our nose and we don´t see it.