Bad Shadows/Composite Materials

[Daf]

Hi all! :)


Is there a known issue with Mental Ray (Max 2009) and composite materials? See screen grab - top block's shadow turns ugly when it falls on a composite material - this is with an MR Area Omni (altho it does it with all sorts of lights!) and Ray Traced Shadows.

When using the composite materials the only shadows that don't get nasty is the shadow map - but I'm not going to be happy using that option.

The shadow density in the screen grab is set at 9 - this is a left over experiment with shadow maps - please note that regardless of the setting the shadows look exactly the same.

Also - as suggested in another forum I have tried more/less photons with no effect at all.

Other settings that may be of interest - Logarithmic Exposure (disabling makes no difference), Final Gather (disabling makes no difference)....

Just wondering if this was the norm for MR and whether anyone had a work around.

Thanks!
Daf

http://www.dreamscraps.com/badshadows.jpg

[Shimrod]

That's very strange. :confused:


Don't you have two meshes overlapping ?
Have you tried mixing A&D materials instead of Standard materials ?

Post a sample of your file, if you want. ;)




If the problem persists, you should maybe unwrap the object to use a simple A&D.

[Daf]

Hi Shimrod,

Thank you for your reply. :)

I don't think I have any mesh overlap. And I am using mostly A&D shaders - but I need to put an image on each open face of the blocks so I was using the composite mode and material IDs.

As you can see in the sample scene - any shadow that falls on the sides using the composite materials is rendered as an ugly black block - but the shadows that fall on the A&D mats are nice and soft.

I'm sure it must be a bad setting somewhere - I'm afraid I'm a bit of a rookie at MR.

Here is the link to the archive - it's rather large even tho I tried to slim it down:

http://www.dreamscraps.com/badshadow.zip

Thank you for your help! :)

Daf

[Daf]

I posted a reply and link to example file ... but I don't see it. What's up?

[peengoh]

I used to have a very similar (http://www.mymentalray.com/forum/showthread.php?t=1429) problem with maya 2008. it turned out i needed the Service Pack! and everything was fine...

hope it helped.

[Daf]

Hi peengoh,

I am up to date on service packs - thanks.

Still waiting for a moderator to approve my post with the example file...:confused:

[Daf]

Right - okay I give up.

Will post elsewhere, but I appreciate the replies. :)

[Shimrod]

Upload it on a free hosting serivce, like Megaupload ou Rapidshare. ;)

[Daf]

Hi shimrod,

I uploaded it to my own site. That was not the issue - apparently a moderator has to approve posts with links(?) and so far it has not been approved.

Not to worry - I have posted the link to the example file on CGTalk
http://forums.cgsociety.org/showthread.php?f=46&t=795523

Please take a look if you want to. :)

Daf

[Shimrod]

I just had a look into your file and... I think you are using a very complicated method to achieve your effect.

I can't say precisely why your Composite messes up the shadows (it's caused by Opacity in the Standard materials, that's all I can say.)


Anyway, I think that your method is not the best for several reasons :

- it doesn't work ! :eek:
- it's heavy at the rendering times to compute 3 or 4 materials per object.
- the modifiers stack is quite complex and add more work to the renderer.


I would suggest (I don't say it's the best solution, but it should be lighter and more efficient) to unwrap your cubes. The shapes are quite simple (and will be more if you detach the white face, with booleans), and you will be able to make quick modifications of your different maps with Photoshop.

Moreover, I suggest you to use Arch&Design instead of Standard materials. A&D are optimized, have more parameters and are more powerful.



Sorry to not bring you the solution to your problem, but I hope I gave you some tips to find the good direction. ;)

[Daf]

Thank you so much for taking the time to look at the problem! :D

I agree that the materials are very heavy - I will look into learning to use the unwrap modifier. You are right on target about lightening the load on the renderer!

In another forum a member mentioned that there may be an issue with MR and the alpha layer in .tifs. That could be a big part of the problem as well.

I have some work to do and some learning to get to!!

Thanks again - I really appreciate the help! :)