Strange transparent effect on opaque object

[Anonymous]

I am having a problem seeing objects that are right behind or inside of an opaque surface. I've tried a standard white material and an Arch & Design white material with the same results.  The material of the "inner" objects doesn't seem to matter either since I've applied the same white material and also see its "shadow".  Could this be a global setting that I've accidentally enabled?  Thanks for any insight on this.

[Francisco_Penaloza]

What render engine are you using??

Either way, it is not recommended to use 100% tone colors, do not use 100% whites or black, keep them around 90% or so.

Also, check your normals on that white wall.

Depending of you render engine could be other problem but we will need more information about your scene setup, render engine, GI, Lights and so.

[Anonymous]

Hi Francisco,

Thank you for the reply.

I am using Mental Ray. 

Regarding not using 100% tone colors, I reduced the white down to 90%, and am still getting the "shadow".

For checking normals, is that just applying the "normal" modifier? I tried that and it made the wall very dark.

[Francisco_Penaloza]

Regarding the normals, there is a checkbox on the modifier panel that will show you the normal orientation, it is a thin blue line (Like hair) that will point in the normals orientation, in your case you need them to be pointing out.

Another way to know is selecting your polygon and click the button flip normal, the face should be bright red, if it is dark red then the normal in wrong, just flip it and it should be fine.  There are many another way to check normal please refer the 3D Max help.

Having said all that, what is your light setup??

I can't replicate your problem.  IS that a close mesh?? it does have openings??

are you using AO option in your material?

What type of GI are you using? Final Gather alone or GI.

What version of 3D Max are you using?

I could try to guess that maybe your GI samples are too interpolated, or average. that sometimes create those dark areas in narrow parts of the mesh, but without more information or having that scene it is hard to tell.

[Anonymous]

Hi Francisco,

Thanks for the replay.

To answer your questions:

• I am using standard target spots and Omni lights
• These are not mesh objects, just standard primitive boxes
• The boxes do no have openings
• The material does not have the Ambient Occlusion box checked under the "Special Effects" dialog box
• I only have Final Gather checked - I don't have GI checked
• I am using 3DS Max Version 2017

When I bring these elements into other scenes, I don't get that "shadow" effect.  Could there be a global lighting or material setting that I need to look at?

Thanks,

[Francisco_Penaloza]

it is hard to tell from afar, could you PM me and maybe send me part of that scene to take a look here.

[Anonymous]

Hi Francisco,

Thanks for taking a look at this. Here is a model and screen shot of what I am seeing.

-Ralph

[Francisco_Penaloza · Accepted solution]

HI,

The problem was the type of shadows you are using. You had MR shadow map, those are kind of tricky to work with.

I am guessing you didn't like the hard shadows or raytraced type.

To use MR Shadow map I would recommend using the Bias check box, and reduce the size to a number very close to Zero but not zero. Then you'll have to increase the Map size (about 5000 or so) and then increase the sample (512 or so)

Now the real solution is to not use traditional lights with Mental Ray and use Photometric lights.

Then you enable shadows, Raytrace type and change the shape of your light to sphere or circle or any shape but point, (use only point with web type of lighting or IES) then increase the size of the light shape and that will control how soft or hard are your shadows.

also how close they are from the light source. just like in real life.

Your problem was that you made that wall with small boxes ( it took me a little to figure out :P)  the with MR shadow map you didn't have enough samples to average the are were two boxes connect, that why you saw the 'skeleton' of all your boxes and joints.

Just use photometric lights with raytraced shadows and you'll avoid many problems 😉

best luck.

Also give to bounces to your Final Gather, if you are only using Final Gather then you should give bounces so you get some Global illumination working.

[Anonymous]

Francisco,

Thank you so much for taking a look at this and spelling out the options - very helpful..!

Yes, I definitely like the look of the softer shadows.

I think I will take your recommendation and just use photometric lights for now on..!

Cheers

-Ralph

[Francisco_Penaloza]

Sure glade to help.

😉