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Undead Fred
02-08-2005, 07:46 PM
I'm working on rendering out my animation I've been working on, and I definitely need to use multiple passes. I'm going to render the background first, then the characters second and key out the greened background and all that, but I was wondering what would be the best way to do the reflection pass?

I've got some glass and a little bit of a reflection on the floor and so forth, so I was going to lighten the rest of the load by rendering the other stuff with raytracing off and then do another pass with reflections. A friend of mine was trying to show me how to do it, but he couldn't quite get it to work right using a regular render layer, so I figured I would ask around here. Thanks for your time.

Daniel Whitton
02-09-2005, 03:25 AM
What I would do is use the Use Background Shader for the object that you want the pass with reflections for,all other objects and any IBL I would turn off their primary visiblity(under render stats) and render out the pass that way. If you need any fresnel reflections you could then run out a pass with a sampler info>Balck/white ramp pluggemd into the color of a Lambert, or even plug a a Ramp Shader into the color channel of your shader(got that one from MPR). Use that pass with your reflection pass in comp to control the fall off of your reflections.

Hope this helps.

Dan

Undead Fred
02-09-2005, 11:31 AM
Okay, cool. Thanks. I'm waiting for the render farm here to get up and running again, and I'll give it a shot then. Hopefully I won't have to do more than one reflection pass... I don't think I'll have the time for more than a few passes.

Undead Fred
02-17-2005, 09:06 AM
Okay, one more question- I'm having some trouble with the test scene to get the passes to compose properly... the scene is just a chair in a polycube "room." The chair's not reflective, the room is. I've got two lights in the scene with shadows. Okay, so how do I get it to render just the reflections and leave an open space for the chair? I was having trouble with the compositing doing nothing more than just laying both passes one on top of the other. You know, like having two full-frame layers on top of each other in Photoshop or something.

The way I rendered it was rendering the chair and the room with no raytracing (but I left alpha on), then rendering the reflection pass by turning primary visibility off on everything in the room and rendering that... (I also tried doing all of that plus using background on the room itself) But the problem was when I tried importing them into AfterEffects, they didn't merge at all... just sat there on top of each other (I had tried the different variations when it complained about the unlabeled alpha channel, but nothing worked). Am I doing something wrong, or is there something different I need to do?

Scott212
02-17-2005, 04:28 PM
It doesn't sound like your doing a very important part. Within your compositor you have to use layer modes to get your passes to properly lay on top of each other. Most of the time it is multiply, screen, or overlay but you can experiment with others. There is a formula for which passes generally like which mode that I'm sure you could find with a little google diggin. After their properly layered, then you just mix the layers with their opacities until you get what you like.

If your layers get weird white or grey outlines, THATS when changing the alpha channels interpretation in After Effects is necessary. I beleive maya is generally premultiplied with either white or black, but don't quote me on that.

Good Luck!

Undead Fred
02-17-2005, 04:56 PM
Ah, okay... I guess I had gotten the impression that I wouldn't need layer effects or something. Do I need to be leaving primary visibility on everything and assign Use Background to them to leave black shapes for the composite? I was pretty sure that the methods listed in the previous posts wouldn't cut out holes where objects sit (the ones that are on top of the reflective surface, but aren't reflective... not sure if that's the best wording). So, when I used a layer effect, I'd still have reflections overlapping my scene objects?

This was my plan for my passes-
1st: Fully furnished room with no characters or reflections.
2nd: Characters.
3rd: Reflections only.

I was under the impression that this would work, but I'm just having some trouble straightening it out in my head before I get started....

Scott212
02-17-2005, 05:11 PM
Here's what I usually do, and I'm not sure if it's right or the best way (in fact I'm sure it's not) but it works.

Create your scene and enable Global render passes at the bottom of the common maya rendering tab. Also, since you want to sepearate characters from furniture, you'll have to use render layers, which are different from render passes. Your layers pallete (where it says `Display`) can be changed to Render. Any layers you create here will be rendered seperately given that `Enable Render Layers` is also ticked in the render globals (right next to `render passes`).

As far as seperating passes that maya's pass system doesn't support (reflections, ambient_occlusion, etc..), I usually just duplicate the file a bunch of times. I then open up each file seperately and apply globaly the shader of my choice wether it be amb_occ, Use Background, whatever. Then I throw them in the renderfarm queue and it renders me some extra passes. If you don't have a render queue just batch render them seperately or create a render.bat file with your command line render instructions.

Cheers~

Undead Fred
02-17-2005, 05:36 PM
Ahh, okay cool. That should do it, then. I was going to put the characters in by rendering with the environment set to green, and the objects in the scene set to Use Background, then just key out the green in the compositing program. I think I may still do that for the characters, but I'm thinking that the render layers might be the answer I was looking for with the reflections combining with the rest of the room. Thanks for your help, and I'll give those a try later on today.

Scott212
02-18-2005, 04:31 PM
good luck amigo.

Undead Fred
02-19-2005, 12:16 PM
Thanks. I've got my first pass chugging away in the render farm, but I'm having another problem and I'm not quite sure what's going on...

In this one area of the room, the floor keeps magically disappearing. This one shot, for example, has the floor partially gone, but then it suddenly reappears when the camera starts moving. I'm not really sure at all why it's doing it, so any help would be appreciated.

(pictures removed)

That last picture is farther into the shot, but the floor pops back in pretty much right when the camera moves. I've done a test in another shot where the camera's still, and the floor was just fine... I'm not really sure what's causing this.

Davain
02-19-2005, 07:57 PM
try changing the "near clipping" in the camera settings.

Undead Fred
02-19-2005, 09:39 PM
A friend of mine had mentioned clipping too, and I tried setting it from 0.010 to 0.001, and that still didn't work...

Davain
02-20-2005, 12:08 AM
It will sound strange but have you tried increasing it? Try setting the "near clipping" to .1 or 1.

Undead Fred
02-20-2005, 12:32 AM
Ahh... yeah, that does sound strange, but I'll give it a try... I'll let you know if it works or not.

Undead Fred
02-20-2005, 09:23 AM
I tried turning it up to 0.1 and then 1, and back down to 0.001 and compared the results, and they were all the same (chunk of the floor missing). I also tried turning off "auto render clip plane" to see if that helped, but none of those options has so far. :sad:

Anyone know what else I can try?

Undead Fred
02-21-2005, 05:20 AM
I'm wondering if there's some sort of glitch happening that's causing it instead of a clipping plane problem? I would think that more than just the floor would disappear if it was? I had some more renders come back and I'm still having that floor issue.... some shots had even more floor disappearing. I'm wondering if it's an issue of the computers getting lazy on certain parts of the shots? Or is it still the camera?

EDIT: I've also noticed that the outside hallway has pulled a similar trick... I don't have the shot handy right now, but the shot of the front door with a section of hallway showing also has the hallway geometry missing... I've checked the render stats on the geometry, and it's SUPPOSED to be rendered...

BonoMan
02-21-2005, 08:01 PM
I'm wondering if there's some sort of glitch happening that's causing it instead of a clipping plane problem? I would think that more than just the floor would disappear if it was? I had some more renders come back and I'm still having that floor issue.... some shots had even more floor disappearing. I'm wondering if it's an issue of the computers getting lazy on certain parts of the shots? Or is it still the camera?

EDIT: I've also noticed that the outside hallway has pulled a similar trick... I don't have the shot handy right now, but the shot of the front door with a section of hallway showing also has the hallway geometry missing... I've checked the render stats on the geometry, and it's SUPPOSED to be rendered...

Hey Kurt...been working on the scene. I noticed that the more internal edges I delete the more of the surface that doesn't show up in the render. Now I know what everyone is thinking but I'm not actually deleting the geometry...just some internal edges. So there's something wonky going on with the geometry that is tripping out the render. We need to clean it up and get all loose edges merged.


edit: Ahah...just fixed it. It's a temp fix but it'll work for now. I just took the cut tool and added a little more detail and voila! The floor now appears correctly in the render.

Undead Fred
02-22-2005, 06:05 AM
Awesome. I'm thinking that the Optimize Scene thing may have tampered with the floor and a few other little things (especially since I had only recently run Optimize Scene on it and just now started getting the problems). I'm going to try and use the pre-optimized geometry, but even if that doesn't work, it shouldn't be any problem to re-make them.

I appreciate your help!

Undead Fred
02-28-2005, 01:35 PM
This post was moved to another thread... (I figured it was different enough to warrant a new thread title)

Undead Fred
03-19-2005, 09:30 PM
Okay, I've got another question. I was working on my third pass, and any of the shots with all of the characters in choke with raytracing on. In case you didn't know (I THINK I had mentioned this in the other thread I had going), the third pass is the floor, the long window on the side of the room, the sphere around the room with the environment on it, and the ribs on the windows outside of the glass. The rest has all had primary visibility turned off. I have BOT textures for anything using textures, and I had even tried turning reflections and refractions down to 3 each and separating the floor from the rest of the room. Now, my question is, are there any OTHER methods for trying to lighten the load on my renders to get the reflections to render without getting "memory exception thrown" errors? I had to go ahead and render those shots without raytracing on, but I was thinking about trying Use Background on the window and floor and making a fourth overlay layer or something. I'm not quite sure that would work, so if anyone has any last-ditch effort tricks I can try, please let me know. Thanks!

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