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View Full Version : (F9) and (F10) issues. Need advice


4dartist
02-17-2003, 05:13 PM
Having Problems with F9 and F10

The renders turn out different. I get this artifacting when i use F10 or LWSN in the shadows and having trouble resolving it.

This 1st one is a frame of LWSN and the F9 render.
http://www.4dartist.com/cgtalk/Goodandbad.jpg

This is just another from of LWSN or F10 render. The artifacting is all over the neck. Also during the LWSN render if the character rotates his head sometimes the artifacting goes away. And i can't F9 600 frames of animation hehehehe.
http://www.4dartist.com/cgtalk/Bad.jpg

All my shadows are shadowmaps. I do have negative lights in there, Using the shadow trick. (Light A 100% with shadows and Light B -100% without) I say this becuase its on odd trick and maybe other people have had this cause problems but maybe not. It works find in other scenes and some frames of the animation. I don't ahve any raytracing shadows.. (mainly cause they are so sharp) And Raytrace shadows are on. Refection Refraction and Transparency raytrace are on as well. mainly for the eyes of the character.

Any ideas? Thanks for anyhelp!

Jockomo
02-17-2003, 08:21 PM
Shadow maps are evil!
I would suggest using either raytraced shadows, or area lights.

I have a feeling that your problem is related to the fact that shadowmaps have a particular resolution. The jagged edges that are showing up are related to the aliasing that happens because the shadowmap size is too low.

Your inconsistance with LWSN may be due to the fact that SN has a different "shadow image" buffered which is created on the fly in each version of SN running. (notice the "cache shadow map" feature.)

Attached is an example of a really bad shadowmap. The shadowmap resolution is really low- like 120ish- just to amplify the problem for an example.

I could be wrong about some of this, as this is just the way I understand it, and welcome any clarification. But hopefully this is the right track to solving your problem. I have avoided shadowmaps eversince I saw the jaggies moving around on a object that was static in an animation, so things may have changed some since then.

Rabid pitbull
02-17-2003, 08:38 PM
that is odd that a still renders differently depending on f9 or f10...

seems like more than shadow map trouble. just as a side note if you use shadow maps shading noise reduction can be helpful with tearing.

4dartist
02-17-2003, 08:43 PM
Hum... My shadowmap resolution is up to 1024 on most of my lights. And looks perfect in F9. I don't think its cause the reso is too low on the maps, but what you were saying about cache shadow maps is interesting. I opened the manuel and it says it will use the same shadowmap for the whole "Render Session" Does that mean Same map for every frame? or samemap for every pass for 1 frame? not that i think this little button is a fix to my problem but was interesting.

Jockomo I have a question for ya! You use raytracing shadows right? So how do you get them nice and soft like you can with shadowmaps? I like the idea of raytrace shadows. But they look like sharp lines nomater the distance. I image there is a pluggin or 2.. or 200, is that what you use? or is there a way in LW to get better lookin raytrace shadows?

Area lights.. *shiver* I LOVE the way they look, but i tried a scene with them in there and OMG my rendertime went from 5mins to 40mins a frame. :( That would take us a week to render a shot. I must admit im not a lighting or rendering master by any shape or form, this is hard work for me.

Rabid pitbull
02-17-2003, 08:56 PM
using the cache map feature WILL screw up animations, espescially if motion blur is on.. only for stills.

4dartist
02-17-2003, 09:24 PM
I rendered out 300 frames last week using LWSN on 4 different computers and most were ruined by that artifacting that you see on the 1st post. So opened LW and rendered the same frame that was bad in the LWSN render and it looked good. So last weekend i set up LW to render 400 frames (on one processor) using F10 instead of Screamernet and 90percent of the frames show the artifacting issue. So without even closing LW after the render finished i hit F9 and rendered one of the frames that was bad, and it looked good. Now after closeing LW and doing more renders i can't actually reproduce the artifacting.. I am trying the F10 again and rendered 3 frames that showed up bad in the weekends render and they seem fine. So i guess ill try to render a portion of the animation tonight and see the results in the morning. I swear LW hates me.

4dartist
02-17-2003, 09:26 PM
Rabid Pitbull: Thanks thats info im glad to hear. Another thing to double check so i don't accidently ruin hours of renders hehe 8)~

Jockomo
02-17-2003, 09:35 PM
sigh, I wish I had an answer for ya :\
Personally what I do is similar to what you were originally talking about. 2 lights in the same position, one is used to light the object and has shadows off, the other is used to create the shadow(much lower intensity).

Unfortunately imo lightwave doesn't have a particularly good solution for rendering soft shadows with good render speeds.
I could be wrong, and hope someone can show me the light. (eww pun unintended)

The thing about the cache shadow map is also what leads me to believe your problem with LWSN is related here too... The shadowmap is an image that is generated at render. Since they are relatively low resolution images, they will be different each time they render. (especially when rendered from 2 different engines or instances of SN.)

Try cranking up your shadowmap size on all of your lights, waaay up, just to see if that makes a difference.

DigitalDeuce
02-17-2003, 09:52 PM
Increase your shadow map size -- good advice.

There's a really good article in Keyframe magazine on Shadowmaps -- recommended reading.

4dartist
02-17-2003, 10:59 PM
OMG lol!!! I missed a light that had cache shadowmap checked! Which would probably explain why when i render frames 455 - 458 they look great and any one frame alone it looks good but when i start at from 1 and go from there it looks bad as the animation goes on. I smacked that one silly light around a little bit.. We cried.. we laughed...
Thank you guys sooooOOOOOOOOoooooo much... I would never have solved this without you!

:applause: :applause: :applause: :applause: :applause:

Well i guess i won't know till tomarrow when its done rendering hahaha!
*prays*

Rabid pitbull
02-17-2003, 11:05 PM
phew!! let us know...:thumbsup:

4dartist
02-18-2003, 05:13 PM
Sweet love it worked 8), that issues has been wracking my brain for a couple weeks now! But i was able to render about 300frames over night on about 5 processors and they all look great! My boss was glowing today 8)~ after he found out the problem was resolved. Thanks guys so much!

:bowdown: <---- ME!!!

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