Ceiling Absorbing Scene Color (FG+GI) MR 8.5

[CiaranM]

I would recommend that you use the ctrl_raytype shader, which you can find here:
http://www.mymentalray.com/mymr_shaders/shaders.htm

With this shader, you will plug the floor's lambert output into the eye port of ctrl_raytype. You can then also pass the lambert output through a math node (multiplyDivide etc.) then pass this scaled value into the FG and Photon ports of ctrl_rays. Then pass ctrl_rays onto the shader group. By doing this you can scale the FG and photon contributions of the floor shader without altering its own appearance.

Very nice start though!

[RMutt]

Wa...? I'm not that advanced....I'll try my best to see if I can do what you're saying. Thanks for the help.

[eem]

I ran into an issue like this once where the light was buncing too far, too much. I found taking down the reflectance, both value and color, on the mia_material fixed it up without having to do any funky things that break from physically accurate. So I would first suggest use mia_material instead of dgs, fiddle with the different presets and reflectance settings to see how it affects the overall light distribution. The mia_material is also documented really well in the maya help file, it's worth the read if your gonna use it. Also, I would only use multibounce FG, I don't think GI would offer any benefits in this still.

[tlggungor]

maybe you should open the wood shape and select the final gather and reduce the final gather rays for wood plane...sorry for my terrible english ...

[bgawboy]

If you are using the Maya lambert, I don't understand why you are also using the photon_basic. This would make it a bit tedious to ensure that the colors are the same for your photon reflection as they are for the material. Maybe I understand if you want a different color for photon reflection, but I would start with the basic lighting characteristics first. With this scene I would agree to try FG only, enabling secondary diffuse bounce to cover for what the GI added. I also agree that the mia_material is what is now recommended over DGS, especially for this kind of scene, or anything that might start having glossiness.

Background information on how the maya materials relate to the mental ray custom shader slots ...

Using a Maya lambert in the surface slot of the SG means you are using a material, shadow and photon mental ray shader automatically. So that Maya Lambert knows how to handle transparent shadows as well as photons, and they all share the color from the UI. (These three custom mental ray slots should probably be grayed out to indicate that this is going on.)

Putting a shader in the mental ray custom shader slots in older versions of Maya used to override only the slot that was entered. For Maya 8.5, if you put a shader in the mental ray custom material shader slot, it will also clear out the shadow and photon shader that is associated with the original Maya material as seen in the Surface slot at the top of the SG AE display.

If you use the Right Mouse Button on an object and assign a custom shader directly to an object, it will not put anything into the Surface slot, and will use all the mental ray custom shader slots directly. This way you don't have to worry about what might be happening with these connections without you seeing it.

Finally, if you RMB for the mia_material in 8.5, it will stick it in all three slots for you.

[bgawboy]

A couple of other confusing terms to clarify.

In Maya 8.5, the Area light is a point light with area. The spot light has an area light AE section to enable in the mental ray tab. Even though they seem quite different in presentation in the UI, they are basically similar except for one being a point and one being a spot light. So I would say you have a combination of area lights, 1 point and the rest spots. Is there one covering the area of the window itself? Knowing where they are might help.

High samples is how many times you will sample the area light from an object with a direct hit from the eye ray. I can't remember what 0 translates to (I think 9), but I would set it to be clear. Low samples specifies the area light sampling from a surface that is back in trace depth, ie the eye ray bounced (or transmitted) and hit a different surface, and now that material is sampling the area light. The High sample limit tells us at which trace depth level to use the low samples.

[bgawboy]

Now if you want similar illumination levels as your GI, but with FG only, try using the FG scale to increase the illumination from a single secondary FG bounce, which is what Maya 8.5 now defaults to, when enabling secondary Diffuse Bounce.

If you know how to get to the miDefaultOptions node you can set this higher, but for your scene I bet just using the FG scaling factor could get you the same look (similar illumination levels) at faster rendering times.

Tip: To get an illumination reference, use a test render with FG+GI, or high secondary diffuse bounce FG without GI. Use the reference for setting the FG scaling factor.

Finally, with this background, we can address the brown tone. Since the scaling factor is a color input, you could use it to tone down the brown diffuse reflection (I wouldn't call it absorption) in your scene from the floor. I would also guess that the heavy brown tone comes from floor bounce but no wall bounce. Though most of the light comes in and hits the floor first which then colors it brown. If there is glossy/specular on the floor, see if that can be set to a whiter color. Then the secondary specular FG bounce (reflection) could be added in to tone down the brown color as well. It might be subtle, so compare saved images to see any differences.

[RMutt]

Thanks for the replies guys.I've been busy...sorry for taking so long.

CiaranM, I currently don't have any ctrl shaders installed. I'll give this a try soon.

tlggungor, I couldn't locate a final gather setting for the material in the attribute editor.

rygoody and bgawboy, I get the impression it's the material...I'll do a test and post my results. I never heard of using mia_material before...I'll read up more on this.

I tried lighting the scene with FG only and it got way to dark and rendering times shot up.
I also tried switching multi bounces for FG to on and played with a wide range on settings...little to no change.

[Ash-Man]

here is my $0.02 on the topic.....
I would think it has to do with the photons size and the number of divisions your ceiling have.

I can’t tell from the picture , but if you post a Wireframe , it might either proof or deny my theory

Add more subdivisions in the ceiling simply by using the cut tool, so the photons can reach to the neighboring pixel rather than having to stretch sp far and wide

[RMutt]

I subdivided the surface...got the same exact result.

[romeu]

you could try lowering the irradiance color of the floor shader.

or instead of the texture of the floor mapped in the photon shader difuse, try using a similar color with less saturation.

[Ash-Man]

is it just a plane...does it have a thickness ?

[RMutt]

The ceiling itself is part of an object with a total of 5 faces while the floor is just a plane. In essence the scene is a room....but only the floor has been segmented in order to attach the wood texture to it.

http://img383.imageshack.us/img383/945/30233626ul5.jpg

Several people have requested the scene as per curiosity with regard to the quality of the render in contrast with the short render time.

I ask that you do not reclaim use of my scene in your personal work or commercial activity. Please offer your assistance if you can by taking a look at the scene, noting your revisions to solve the problem/s and repost the file.

Link 1 (http://www.sharebigfile.com/file/146465/Rmutt-Room-Scene-zip.html)
Backup (http://download.yousendit.com/1C3AE8E62AE10094)

I took out the chair, as you should have no use for it...

http://img394.imageshack.us/img394/4323/84742176ws8.jpg

[talama76]

I took a quick look to your scene and the first thing i noticed is that you have visible in reflection and visible in refraction turned off for all the object (this usually happen when you import from obj).

Also your scene size is probably too small (60 x 90 cm).

Sorry for my english

Ciao,

Luca

edit: i double checked and you don't have vis. in refrlection/refraction turned off. I need to sleep more :). sorry

[tlggungor]

I try to render your scene...And change the dgs shaders and replace the mia_shader


http://i53.photobucket.com/albums/g66/tolgahangungor/tolgahan1.jpg

this shader included ao pass and render is very fast...2500 x 1700 it tooks 2.5 hours ..

[ghostlake114]

I have look at your scene and must say you are using a "weird" setting when eliminating light intensity also do not use a light shader for intensity. So your lighting is base all on photon intensity. This is so interesting and I never try it before... althogh in theory, this will cause weird in decay but your scene look good and render time is impressive!
===
With this setting, no need for any tonemap shader (mia_exposure,ctrl_buffer) because you do not have any overburn area...

[RMutt]

Very nice work tlggunger, could you repost or pm the file so I can better understand the changes you made. It's much easier for me to understand by seeing the visual changes.

ghostlake114, could you explain more about using a light shader to control intensity? My render is lit through the photons....I was usder the impression that the combintation of real lights + photons should be used for interior scenes. Could you talk more about this and tonemapping...I know absolutely nothing about these things.

[eem]

Ok I looked through your scene. The changes I made are:

-Changed mitchel filter to triangle 2 2, I just like this one, it's fast and softens it just a little

-turned off GI

-Turned off radius control for FG, it's unneeded
-Set FG accuracy to 100, 400 is just waay too high, you could even get away with 50
-point density to .1, you may want to use more than .1 if you had a more complex scene
-interpolation to 100
-FG secondary diffuse bounces on
-filter 1, play with this setting, it has a direct effect on interior lighting levels

-put mia_material on everything, adjusted it properly, you can read about mia_material settings in the maya docs.
-Turned AO on in the mia_materials, set to detail, set radius to 32, roughly half the room size

-Deleted all your lights, created just physical sun and sky, pointed the sun at the windows. The FG calculation is good enough now that you really don't need to to do tricks like putting lights in the window. You can rely on just FG

-Your normals were pointing the wrong direction on the walls, I flipped them. You also modelled the windows as a hole in the mesh, so I had to reconstruct a portion of the wall. Don't make holes in your mesh, always keep atleast one edge running to every window.

http://www.yousendit.com/transfer.php?action=download&ufid=B772949871806BEF

[RMutt]

:eek:

rygoody WOW...thanks for your help. I haven't even looked at the scene yet, but it's quite obvious that you took time to lend your assistance in every way possible. This comes most appreciated as it's the little things...those quabbles that no one corrects us about that add up to problems later on down the production pipeline.

Once again-thanks for your assistance.

[myself44]

Looking at your scene I find the lighting awesome. I know, it's not very constructive, but if I could light as good as you are, I'll be happy.
Im just have a curiosity here, every scene I see, the light size is always huge, why in my scenes, the light is always very small, does it have an influence ?

I just cant get GI and FG work, whatever I do. Also, I wanted to learn from your scene, but cant open it : wrong version...

http://i14.photobucket.com/albums/a350/myself-44/int.png

[RMutt]

I never really considered light size as a factor in my scenes. I size my area lights to that of the window dimensions. For spot lights I make them large because most of the tutorials (guys like dragon and others) explain that your are effectively using the spot light to represent the sun.

I'm about to look at rygoody's scene. It seems like MR Physical Sun and Sky might be a better solution for lighting a scene realistically.

I would like to help you, but I no longer have Maya 7.0 on my workstation. Will an .obj file work? IE include the node/texture connections?

In any case-when I understand what changes were made to the scene I'll do my best to explain the setup.

[RMutt]

rygoody, there's a white buildup...almost residue on the floor. What do you think is causing this? I also obtained the same result:

http://img404.imageshack.us/img404/3161/58821201ww6.jpg

I tried changing the floor texture...thinking it could just be something I didn't notice, but that's not the source. Reflections of the walls and windows maybe? :shrug:

http://img207.imageshack.us/img207/395/33469746ah2.jpg

[tlggungor]

how can I post my scene ?

My mail : tlggungor@yahoo.com

[RMutt]

I like to use http://www.yousendit.com

[slipknot66]

Honestly i see nothing wrong with your render, the light is bouncing around because the room its empty.As rygoody did, you can control the amount of bounces or even if a material reflects too much inderect light.

[RMutt]

I've seen your renders in the other threads in this section and they are impressive. So that coming from you tells me I'm getting somewhere.

Mia_material is amazing. I started reading up on it in the help files last night and the opportunities to create realistic materials are much broader than the normal maya shaders.

From what I understand thus far it seems to be the foundation material upon which you add your various nodes and settings. From this backbone you can create beautiful results in terms of metals, stone, ceramic, glass, glossy wood and flooring. all the materials that are perfect for interiors...so much so that they say it:

"The mental ray mia_material is a monolithic material shader that is designed to support most materials used by architectural and product design renderings"

The settings are easier to understand and the help documents go through them in such a way that even an impatient learner like myself can understand and absorb the material (no pun intended). I haven't been this excited about Maya in a while.:)

[RMutt]

rygoody, I think the color on the wood is due to the reflectivity settings. Things like reflectivity, reflection gloss and reflection gloss balance.

I was playing around with a new scene while at work today to see if I could improve upon my last wood texture. Ignore the walls...as I didn't have time to tweak mia_material settings for them walls. The wood is still pretty rough, obviously still needs lots of tweaking, but a good first attempt I think for a first try with mia_material.

http://img19.imageshack.us/img19/5871/10343929am1.jpg

I also want to start playing around with the mia_exposure_simple. I always read threads with posters talking about gamma...but never figured it out. They get into it a bit in the Help but not much.

I'm so envious of all the beautiful Vray renders on the net. I'd like to work my way towards that level in maya w/ MR. :) I think your renders Slipknot, exemplify what I'm talking about...really great stuff.

[tlggungor]

change your gamme settings to 3.000

[myself44]

ok there's a bit of confusion for me... when you talk about lights : spot light , ok. Area light, is it the spot light with the mentaray area light OR the area light of maya..?

If i understood, you place an area spot light for each window(s) to shoot photons and you place a spot light to create the sun light?

[eem]

The white on the floor is a reflection, the way it looks is because I bump mapped it as well with 'no diffuse bump' checked in the mia_material. Which makes it only bump the specular/reflection which is how you do that lacquered wood floor finish.

[RMutt]

God this thing has me frustrated. I"m trying to brighten the scene and I've tried several approaches without the results I want.

I've tried adding GI via an area light in the window everything from 50,000 photons to 5,000,000,000 and no change...I must be doing something wrong. Do I have to attach an mib_photon_basic to the mia_material for it to absorb photons? I'm not sure if it does it automatically or i need to plug it in manually. I tried both approaches with a result that isn't much brighter.

I'm attaching the scene for anyone who'd like to take a look and offer some advice/assistance. Here is a recent render with a better wood texture applied to the floor. No post processesing in PS:

http://img54.imageshack.us/img54/144/77769529ry5.jpg

I've tried changing the frame buffer Gamma setting to (1/2.2=0.455) but the result looked washed out. At first i thought it looked better with the new gamma...but if you look at the left side of the floor...the wood looks washed out. Not hat it was vivid to begin with, but I want the floors texture to be more vivid and I don't know how to accomplish that. I should also note that there's a seperate gamma correction of 0.455 attached to the floor texture:

http://img180.imageshack.us/img180/6743/washedoutfx0.jpg

I tried adding GI....but the color doesn't "pop" the way I want it to. I'd like the render be have a brighness and contrasts similar to this:

http://img293.imageshack.us/img293/4778/02sp6.jpg

Another issue I'm having is the bump map for the floor isn't showing up. It might not be necessary, but it's annoying me that it isn't showing up. I'd just liked to see how it looks.

Scene link: http://download.yousendit.com/965B4FD3767B4A10

[RMutt]

bumping this thread.

[eem]

Why are you adding GI to brighten it? Shooting more photons into it will not brighten the scene as the photons will be sampled to the same brightness of the room. Photons are samplers of the light, they are not light. You don't even need GI, it serves the same purpose as the final gather secondary diffuse bounces. When you turn on GI it actually disables diffuse bounces on the final gathering. For still shots secondary diffuse bounces is the better method to go about it as it's easier to set up and it only samples the lighting where the camera is pointed, GI shoots photons all over the place.

When using the physical sun and sky the only thing that affects brightness is the exposure controls. As the brightness of the sun shape is driven by the physical sun calcuations and you don't want to artifically inflate it. Go into the tonemapper attached to the camera and turn up the gamma and the gain. Or attach the tonemapper from ctrl_buffers and start reading about how to use it in the ctrl_buffers threads because it is a superior tonemapper to the defaul mental images one and will produce better results when setup properly.

Another thing, you don't really need to change any settings in the scene I posted to brighten it. Just render it to a 4x32 exr format then adjust the exposure and gamma in photoshop. Or even take it into HDR shop and run a more advanced tonemapper on it for better results.

The brighter more contrasted look of the office render you posted is partially due to the windows being bigger letting more light in and the room being smaller, bounces pick up more light. But primarily the look it has is caused by the tonemapper used in it. IIRC, that is a shot showing off the ctrl_buffers tonemapping functions isn't it? The lighting I set up in your scene is correct, it's about as physically accurate as you need to get. If you want to change the final look you do it through tonemapping. Try using the ctrl_buffers tonemapper.

[RMutt]

Thanks :) I'm been avoiding the ctrl stuff...but I guess their use is inevitable.

[Gabba]

I'm with rigoody, try the ctrl_buffer or another tonemapping!
I've downloaded your scene. For the bump mapping, create a mia_material node and use the SG of this node. Don't create a connection to a lambert SG. I think that is what don't let it work. If you don't get any result even trying to do directly with the mia SG, try other values in the values of the bump mapping!
For the gamma problem with the framebuffer. If you used the phjysical sky Maya create a simple tonemapper and attach it to your camera (the simple_exposure) so you have a gamma correction, let's say a 2.2 gamma correction by default. If you don't detach this node, and apply another 2.2 gamma correction it's obvious that you have a washed out look! You have doubled the gamma correction! So if you want to your wood look right (maybe I'm wrong I don't know if in this case the gamma must be added each other) but you must do 1/(2.2*2)=0.227 so in your gamma correction node you need to put a value o 0.227 instead of 0.454. Maybe I'm wrong with the calculation of the right value for the gamma correction. But I think that the problem is the double gamma correction. The one of the lens shader and the one of the framebuffer.
When I can I upload an images ;)

[Gabba]

Here is an image i did. The bump is too strong just to let you see how it work (I used the way i said before). Byeeeeeeee!

[Tobbe]

If you are using photons... don't forget to make sure you have the mia_material attached to the "Photon Shader" slot in the shading group.

Cheers.

[CiaranM]

You should stick with using GI photons as well as FG. I would argue against using FG multibounce alone.
When you use photons, not only will you get more of a "physically accurate" result, but you will be able to calculate many, many bounces in no time at all. FG will then smooth out the illumination and bring out some details.
Try doing a FG multibounce render with more than 3 bounces and any kind of accuracy and you'll be waiting a loooong time.

[eem]

CiaranM, would you be willing to set up the scene properly with GI? I'm curious to see a comparison test vs seconday FG bounces.

[cpan]

IMO FG+sec diff bounces is nice in outdoor scenes. But in this kind of indoors, GI+FG might be a better option.

a first test with GI+FG
http://img153.imageshack.us/img153/5242/rmuttroomsceneie4.png

[RMutt]

Very impressive Yashu. :) Would you mind posting the scene so that others can observe the changes first hand.

I'm beginning to think I prefer the look of the GI+FG over just FG with Multi bounce. The ceiling absirbtion is still here even though i swithced over to Mia_Materials. I figure i need to play around with some of the settings a bit more before I get it right. This is the original scene since I'm at work right now and the only one I could find.

http://img522.imageshack.us/img522/1834/75129609pw2.jpg

[myself44]

Very impressive Yashu. :) Would you mind posting the scene so that others can observe the changes first hand.

I'm beginning to think I prefer the look of the GI+FG over just FG with Multi bounce. The ceiling absirbtion is still here even though i swithced over to Mia_Materials. I figure i need to play around with some of the settings a bit more before I get it right. This is the original scene since I'm at work right now and the only one I could find.

http://img522.imageshack.us/img522/1834/75129609pw2.jpg

Wow, nice rendering. Can you tell me which settings I have to enable/tweak to have this depth of field effect in my images ?

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.