Samab 05 November 2009 06:12 AM

Jeff, that’s a neat trick putting the Transmat in the Camera Mapped Background. That’s what I was missing when I did the scene in this thread. I had trouble getting the balance between the Physical Scale setting and the EV to get the M\S\R to show white without bleaching the objects. Telling the Exposure not to affect the backgroung worked for the background, but not the white of the M\S\R material.
When I tried to re-create it in Max 2009, I could not get it right.

Samab,

I’m trying to wrap my head around what’s being discussed in this thread, but two terms are alluding me: “Transmat” & “M\S\R”.  Basically I understand what’s going on with the Background Switcher, Camera Map, Physical Scale, & some of the Matt Shadow functions, but when Jeff Was elaborating on Transmat in the Camera Mapped Background I got lost.  Can you clear this up for me?  I think “M\S\R” is short for the Matt Shadow Reflection material, but I do not want to assume that I’m reading into in correctly.

Chris Robinson
http://www.supercoonstudios.com (Under Development)
3ds Max 2011
Dell Precision 690, Intel Xeon Dual Quads @ 2.66 GHz, Dual NVIDIA Quadro FX4500s, 12 GB RAM, Windonws 7 x64

Yes, by M/S/R I mean the mr Matte/Shadow/Reflection material. Transmat is another mr shader who’s purpose is to do absolutley nothing, that may seen useless, but it does have it’s uses. An example being if you want a geom object filled with a Volume like PartiVolume. Start with an empty mr material, if you put transmat in the surface, it will have no surface, put it in the shadow too, and it has no shadow, then put the volume shader in the volume slot. You end up with a material with volume that renders but no surface.
In this case it was used to make the M/S/R material’s background be the same as the environment background. If you know the M/S/R material, you know it has a slot for Camera Mapped Background, typically it is used for a background image by putting the mr camera map background shader in it with a map. But what Jeff did was put Transmat in it instead, which mean’s it’s background is nothing, so therefore shows as the environment background which is set to pure white, but is not affected by exposure control.
What I was doing before was just leaving the M/S/R’s background colour swatch white. But that is still affected by exposure control even when the “don’t affect background and environment” is on. Which meant I had to mess around with the Physical Scale setting to get it to render pure white, not grey. Actually getting it to render white wasn’t difficult, the tricky bit was not overdoing the physical scale, so the ground was white, but I didn’t lose the shadows or over expose the subjects.
Jeff’s trick with the transmat eliminates that problem because it makes “don’t affect background and environment” apply to the ground plane too, so whatever you do with the exposure, it was always pure white.

Hey guys, I found this thread which seemed to be answering the question of doing exactly what I want.

I’m creating a 3d graph in max and want shadows and reflections, but no surface so that I can use the alpha channel to hide everything but the graph bars. I’ve read this thread and have it working someone.

at first I selected an MSR material and when that didn’t work I figured out that Transmat was the one I wanted. So I changed me plane (ground) material to a transmat and that seemed to receive shadows, but the ground plane itself did not show up in the Alpha Channel, which is what I wanted.

One small problem, I’d also like to get reflections on the ground, but without the ground plane. So I want reflections in my scene, and I want the Alpha Channel to have the reflections, but I still don’t want my plane in the Alpha Channel. Is this possible?

my specs are this quad processors, 8 Gb RAM, windows xp64bit, 3ds max 2011

garek007 08 January 2010 10:49 AM

I’m creating a 3d graph in max and want shadows and reflections, but no surface so that I can use the alpha channel to hide everything but the graph bars.

One small problem, I’d also like to get reflections on the ground, but without the ground plane. So I want reflections in my scene, and I want the Alpha Channel to have the reflections, but I still don’t want my plane in the Alpha Channel. Is this possible?

Unless I’ve misunderstood what you need, all this should be possible with the methods outlined in this thread.  See attachments.

If this isn’t what you’re needing, then you could always render out in passes/elements and composite together for the results you’re seeking.

Jeff Patton
My Website | mental ray materials & blog

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Great info from Jeff, Samab and of course Zap.  Thanks all for your insight!  Did a test scene in Maya/mr and got great results.  Unfortunately, I haven’t had the same luck with VRay. 

I’ve been banging my head against the wall the last couple days trying to replicate these results in 3ds Max 2011/VRay 1.5 to no avail.  Has anyone been able to translate this workflow to VRay?  I can get shadows and reflections to catch on a transparent plane using a Mtl Wrapper.  However, my reflections get blown out when I render against a white environment. I’m not sure if there’s an appropriate substitute for the mip_matteshadow shader or BG switcher in Vray. 

I’m using a VRay Physical Camera (exposure on) and a VRay Rect Light.  Perhaps I should test with a standard camera and Max area light next?  I’ve also attempted plugging a VRayMap into the environment slot to dial out the reflection contribution from the environment, but it’s causing my scene to crash. 

I’ve been combing through the Chaos Group forums as well and still haven’t come across a Vray solution for rendering reflections on pure white.  Any help would be appreciated.

Thanks!

Hi,

I’m using 3ds Max 2009 and having trouble with the environment background switcher. I have put it in the environment map slot then instanced it across to a slot in the material editor where I have then changed the background to white and left the environment/reflections black. I am after a white scene where a chrome material reflects a black background however the background is still coming out black...? What could be the reason for this?

Also, I have used a m/s/r material on the floor plane and like others before have said, the plane shows up in the alpha channel. How can I make it so that the objects and their shadows are the only things that show up in the alpha channel? I have read through the previous commments and I’m still confused! I think it’s because I’m not familiar with the camera map shader that they talk about.

Thanks in advance if anyone can help me!