Sprite_rendering_artifact_( With Deep Shadows ) !!!

[cellchuk]

Hey Guys,

I am working on a tornado effect and using sprites. However, I am getting some artifacts on renders when I use deep shadows. Not in every frame but some of the frames are coming out with this artifact. It basically renders, a part of the image with deep shadows and leaves the other part.

and these are the settings for the shader and the light...

I was wondering if any of you guys had this artifact before.

Waiting for suggestions and replies..

Thanx.

[zoki]

hi

try changing light direction

probably Miguel will tell you best

but after some experimenting after his tutorial and 3d buzz movies I got lots of this kind of artefacts

the way I read it guys usually setup light rig separetly for sprites and the rest of the scene

You must carry in mind that sprite is just flat 2d card in space which is oriented towards camera

so they are very sensitive toward light angle tahat hits them

z

[cellchuk]

hi

try changing light direction

probably Miguel will tell you best

but after some experimenting after his tutorial and 3d buzz movies I got lots of this kind of artefacts

the way I read it guys usually setup light rig separetly for sprites and the rest of the scene

You must carry in mind that sprite is just flat 2d card in space which is oriented towards camera

so they are very sensitive toward light angle tahat hits them

z

Hey Zoki

thanx for the reply,

I m already using a seperate light rig for the sprites. I experienced that the lighting is very important in sprite rendering. However, those artifacts just comes out when the deep shadows are on.

And also the strange thing is that the artifacts doesnt appear in every frame.

-Actually, I've spent lots of time in rendering sprites and I realized that errors just occurs when you make a fast render For instance ( Mantra ip render, Render Farm )

It generally doesnt give too much artifact when you make a " normal , calm , slow " render .

So yeah basically thats the problem that I have at the moment.

Thanx

[zoki]

hi

check also this pdf if you didnt already

http://www.sidefx.com/index.php?option=com...&Itemid=132

here they explain a little more about shadowmaps

It might be also resolution of deepmap issue?

in the viev tab of light you can set it and read about it in upper pdf

and raise z depth samples to 3 3

z

Edited June 7, 2007 by zoki

[cellchuk]

hey,

I ve already tried different z-depth sample rates, unfortunately didnt work.

thanx for the PDF advice. I' ll check it out again maybe I can find some tips about deep shadows.

cheers.

[old school]

When the shadow map is generated, the sprites orient themselves to the light.

When you render the final image, the sprites orient themselves to the camera.

That's the error.

There is no work-around except to use copied grids or move the light close to the camera to mitigate the effect.

This technique works best when the light is more perpendicular to the sprites as viewed from the camera anyway.

I wonder if there is merrit for an RFE to have an option in the sprite procedural to orient the cards to a specific camera. This would allow more severe light angles (to a degree) generating shadow maps.

[Marc]

One good method of doing it is to copy primitive spheres to the points with alpha and render those as dshads. That way you'll get a nice falloff to your shadow when you use it on the sprites, and you don't have to worry about lighting direction.

Cheers

M

[cellchuk]

Hey,

Thanx for the advices. This explains the error

I'll try that out and let you know about the results

cheers

[cellchuk]

Hey guys,

I fixed the error.

the problem was the shadow maps.

I was using 1 single map for the whole sequence.

Then I generated different maps for each frame by adding $F3.

so the problem is fixed now.

Cheers.

[MIguel P]

Hey guys,

I fixed the error.

the problem was the shadow maps.

I was using 1 single map for the whole sequence.

Then I generated different maps for each frame by adding $F3.

so the problem is fixed now.

Cheers.

I never had this problem, and I don't use a sequence to generate the maps... but thank you, If I have the problem in the future I will know how to fix it.