Mental Ray skills test scenes

#1

Im having problems to download both files (Emil3d, myself44)
Corrupetd files.

#2

Hi everyone, recently I finished reading the entire thread VRay-like interior renders with mental ray??? and decided to test my MR skills with what appeared to be the most popular testing scene in that forum, the famous classroom. There are great examples of superb MR skills like the scenes from Dagon and many other very skilful MR users. I would like to say thank you to all contributors for sharing their skills and renderings.

Although some of those great scene examples were posted at different times, most links are currently dead and some users like me are not among the lucky ones who were able to download those treasures. I found that examining scenes that demonstrates the best of MR from skilful users is much more useful than reading the entire MR related help a million times. Unfortunately there are no scene examples that can serve such purpose included in the official Maya documentation.

I found the classroom scene after a Google search only in Max format. Although it opens fine in Maya and comes with a few non essential geometry problems, all objects have bad or missing UVs so I had to spend about a long day fixing these to some acceptable degree.

I decided to create this thread after participating in another thread in this forum Physical Sky and … moon ? where I used my tests to share my tone mapping and color correction experiences. MrHoo asked me if I would share the scene and I decided to use the opportunity to create this thread as a place where everybody should be able to download the test scene at any time with lighting, materials, and settings set from different users to their best capabilities who are willing to share back the scene after improving it, sharing different possibilities and techniques, or simply contributing to it in any way.

Additional different testing scenes are welcome in this thread. This should be a place where users can also ask and receive help with solving problems associated with shared test scenes. I would like this thread to be limited only to solving problems and sharing skills associated to or demonstrated with shared scenes. So that users can download, open, examine, and test render the scenes themselves instead of only seeing great renders with a few posted settings that remain mystery for many users.

The most important thing it to keep all links and uploads alive at all the time. Any tips on how to achieve this successfully are very welcome. On my part I don’t mind downloading posted scenes and upload them on my space on http://rapidshare.com/ in case an original link dies.

I hope this thread turns really helpful

#3

This is the classroom scene file just converted from Max to Maya 8.5 without any further changes. class_final_vray_reset.rar

This is the same scene file but after I modified it. class_room_shared.rar
If you have trouble with the .rar file this is a .zip version of it class_room_shared.zip
The most important changes are:
The scene was scaled to more realistic dimensions. UVs were applied to all objects. There are no textures in the scene yet. Some geometry was cleaned up. Materials were assigned to the objects. The scene was organized in groups and layers with English description of objects and materials (if my English has failed you are free to correct it). The scene was lit only with physical sun and sky environment. If you render the file using Render View the result should be similar or better to this.

I said similar or better because this image is blurred. And it is blurred because it was first batch rendered to openEXR float x 32 bit file with the mia_exposure_simple disabled and then tone mapped with it using the preview options and color corrected with the addition of HSV remap and Contrast utility nodes. This process is illustrated in more details in the second half of post #12 from this thread.
And this introduces the first of many problems that I have with these test renderings:

Problem 1
Blurred result when using the preview feature of mia_exposure_simple comparing to the sharpness of the rendered file.
To reproduce this, first batch render using the modified scene after disconnecting Contrast utility from the Lens Shader slot of the camera. Next, connect back the Contrast to the Lens Shader and in the mia_exposure_simple node, check the preview box, and for a preview choose the rendered file. The blurring effect will become more obvious if the image used for the preview was rendered with Gauss filter set in the Anti-Aliasing Quality section of the Render Settings. Provided there was no problem with the blur this process could be very useful as node based post color correction solution for any HDR image.

Problem 2
This is not really a troubleshooting problem but rather sharing issues I’m facing that might be common among other users too.
How to achieve a desired goal when tone mapping and color correcting HDR images with the available options, tools, and different programs?
As most of us already know the linear High Dynamic Range images do not fit properly in the limited range and non linear gamma of our monitors. This requires a tone mapping and color correction that is mostly based on user’s eye and perception.

The following examples show my experiences with this:

Method 1: The image shown earlier in this post is what I’m capable to do so far directly in Maya. There should be no blur if the image is rendered using mia_exposure_simple at render time instead of used as a preview. I already described how to reproduce this result in Problem 1

Method 2: the image below was edited in Photoshop by using Exposure, Curves, and Selective color commands.

You can reproduce this image if you batch render using the modified scene after disconnecting Contrast utility from the Lens Shader slot of the camera and then in Photoshop run this action on the rendered image. This took me a lot of tweaking of the Curves and I never got fully satisfied from the results neither as tonal range nor as colors. Like with all other methods the challenge is to reveal details in the bright and dark areas without flattening the image too much and keeping some pleasant contrast but I wasn’t able to make it both ways. May be the fact that the scene is with somehow boring colors, lack of textures, and just one light source coming from the environment, makes this more challenging but I feel the image can be improved much more than what I’ve done so far.

Method 3: the image below was also edited in Photoshop with a process illustrated in more details in the first half of post # 12 from this thread.

I rendered this image form an earlier slightly different stage of the scene. The most noticeable differences are the darker color of the blackboard and less FG artifacts on the walls at the upper right corner of the scene because it was rendered with slightly higher FG Accuracy of 150 and Point density of 1.2
This method requires most involvement but gives more control, although my result is far from perfect.

Method 4: this image was edited with Artizan with the following settings.

This took just a few seconds which is a pretty good result for that time and the good thing is that, like with tone mapping in Maya, the image stays always at 32 bit. I’m using Artizan just by intuition without ever bothering reading or learning how to use it and it is very easy and fun to use. However I’m still new to it and haven’t found more localized control like curves. As you can see on the image the nicer contrast comes at the expense of pale and almost colorless environment color seen through the windows and the direct lit areas of the walls. This is easier to fix in Photoshop with the use of more localized controls.

As you can see all these different methods have pros and cons with different possibilities and this is not necessarily bad but with each method I feel limited to the capabilities of the deferent tools. Of course my skill level may be also a factor in all this and I will really appreciate if other users share their workflows.

Problem 3
is the biggest mystery I ever had. If you compare all images here looking under the window sills and the heater you will notice a strange illumination difference between some of the images. The image displayed in the Problem 2 > Method 3 above and all of the partial images displayed in the last Problem 4 paragraph don’t have that strange illumination under the window sills which was not there in an earlier stage of the same scene. Initially I thought that this is caused by some differences introduced between the 2 stages like the scaling, UV mapping, cleaning of some geometry, and realignment, but after some crazy tests without finding what causes this, I decided to render again directly from the file that rendered the no problem images. To my total dismay the same file that previously rendered images without this problem now renders a different image showing this illumination problem. I’m 100% sure the file was not changed between the 2 renderings. Every time I batch render I save the file and continue with a new version of it. Not only that but Maya automatically produces a temp copy of the scene ending with some 4 digit number and the copy stays until manually deleted. On top of this I have more stages saved as different files before and after and all of them now render with this problem. There is no way I could have accidentally change so many copies in the same way. The only thing that was not the same between the previous and the new renderings was the rendering resolution which I believe should not affect things like that.

Here the 2 images were rendered from the same file – the larger is rendered earlier with 1000 x 750 and the smaller image was rendered now with a resolution of 320 x 240 from the same file. The screen shot was taken from imf_display with the same gamma applied to both just to make them brighter for better viewing.

You can clearly see the difference with the illumination problem. What the heck is going on? Is my copy of Mental Ray possessed by a ghost? Please let me know if this problem shows on your ghost free computer when you render the shared scene from the link. At one moment I thought this could be Mental Ray reading some old Final Gather maps since I have a folder full of them but I triple checked before the troubleshooting test renderings that the Rebuilt is set to on and even deleted names of any Final Gather maps from the Render Settings. I even made a test with removing all objects from the scene except the walls and the problem only became more obvious. If you render this scene with the problem still showing and find what’s causing it you will remove the biggest mystery I’ve ever encountered in Maya.

Problem 4
I’m experiencing big performance hit when rendering glossy mia_materials with high Reflection Gloss Samples. Notice the noise on the top and shelf of the desk, floor, chairs and the blackboard stand. In the scene, those most glossy materials are currently in a separate bin and set to 256 Reflection Gloss Samples. This noise become more obvious and unacceptable with lower samples and will only go away with much higher samples. The problem is that the rendering times increase exponentially when this value is raised.
Here are some noise examples of different Reflection Gloss Samples:

32 Reflection Gloss Samples

64 Reflection Gloss Samples

Even with 256 Reflection Gloss Samples the noise although greatly reduced is still there and renders about 7 times slower than 32 samples. On my slow computer this takes a lot of hours.

Any tips how to speed up rendering of glossy materials with preserving acceptable quality will be greatly appreciated

I certainly can list more problems associated with this scene but I think that’s enough for now.

Thanks for reading all this. I appreciate your feedback and contribution.

#4

I would like to see this thread growing to become a render scene archive. It would be cool!
Emil3d, Im just asking now how do you tonemap a EXR file in Photoshop ? This format seems so limited in PS, no new layer creation, no image adjustment… what is the method of tonemapping a 32 bit EXR in Photoshop?

Also, is it normal when I open your classroom scene, all objects are green, all materials are “unknown”, and when I render, everything’s grey ?..
http://i14.photobucket.com/albums/a350/myself-44/class.png

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Then, I'll contribute a bit by uploading one of my old interior test I did. I modified it to apply me newly learned methods. Before I would like to precise that [b]scenes and any files posted here are for [u]practice[/u] and [u]personal[/u] use [i]only[/i].
[/b]I archived the scene file and all the textures that come along. Scene elements name are in English. I've left pretty much all settings to default so that ppl could be free to adjust to their wishes.

*Download links at the bottom of the post. (I also uploaded to Emil3d’s RapidShare account.)
When scene is opened and rendered, it should look like the image that follows (quality could be improved afterwards; I wanted a fast render to show to overall lighting)

Overall description :

- IBL enabled (sky color)
- Physical Sun&Sky [i]disabled[/i], no mia_exposure
- 1 Maya Area with MR Area enabled. 50 000 photons; rest default
- 1 Maya Area with MR Area enabled. 30 000 photons; rest default
- 1 Direct.light sunlight. Rest default
- Render settings. Low GI and FG values.

[img]http://i14.photobucket.com/albums/a350/myself-44/3D%20projects/interiors/squareRoom.jpg[/img]

Quick adjustments made in Photoshop with Levels, Brightness/Contrast, Shadow/Highlights.
And let's hope, a lot of ppl will post up their scenes to the profit of everyone.

[img]http://i14.photobucket.com/albums/a350/myself-44/3D%20projects/interiors/squareRoomPost.jpg[/img]

—> FileFront link

#5

myself44 thanks for contributing:thumbsup:.

   Yes, Photoshop has very limited options for 32 bits per channel images but I convert them to 16 bits after applying the exposure command. You can reproduce and see all my Photoshop actions by following the instructions from Problem 2 > Method 2 section from my previous message. You have to download, extract, and use the action file in Photoshop from the provided .zip file from the link. In case you are not familiar with how to use the action file here is a quick guide:

Open the rendered x32 bit image in Photoshop SC2 or newer (you can try this with any file but just to see actions). Choose Windows > Actions (or press F9) to open the Actions palette. From its pop up menu, choose Load Actions and choose the action file which name is CC for classroom_shared.atn. It will appear as a folder in the palette. Expand the folder, Action 1, and double click on each action in order to open its dialog window so that you can examine it and apply it.

 Regarding the problem with properly rendering the scene, I don’t know what’s wrong but make sure that you open properly the file by first coping it to the scene directory of your current project and then use the Open command from Maya.

Also I can see from you screenshot that you are using Maya 8.5 without service pack 1 and this may be causing the problem. You can upgrade to service pack 1 here http://www.alias.com/glb/eng/support/maya/updates/pages/maya_85_release_notes.jsp

#6

slipknot66, thanks for you interest, your participation in this forum is very valuable:thumbsup:.

I test downloaded the files from the links in my message as well as the file provided from myself44 and both opened fine. I’m not sure why you got them corrupted but it might be because we are using .rar files. I provided a new link at the beginning of my previous message with .zip file which is larger size but may be more robust against internet travel corruption:). I hope it works for you.

#7

Hi Emil3D

sorry, I saw this thread only now and i am currently at work and can not read it concentrated.
So I will do that at home and will participate strongly in testing and sharing results :slight_smile:

I am glad about this thread because it gives me a great opportunity to step in a very early stage of the topic and grow with it

Thanks!

Cu

Dominik

#8

OKay,

I’m totally confused. I downloaded the classroom scene and did a quick test render - I noticed that there was no GI but only FG enabled?

Last time I checked (Maya 7.0) this kind of lighting was impossible with FG only. One had to use GI and then smooth out the results with FG. Is GI becoming redundant?

The other thing was that accoding to the theory FG was a “fake” rather than a true light model - something like compositing the result of an occlusion pass with a beauty pass - has this changed? The results in the classroom render above one can only get from more than one diffuse bounce but FG unlike GI is supposed to only bounce once?

Whats happening?

#9

In Maya 8.5, a Physical Environment can be created and this will add a sunlight. As for the ‘FG only’, it’s by using multibounce feature. Someone could give more detail and info on this aspect because Im not very familiar either.
But personally, I still prefer to use area photon light in combinasion with FG.

#10

Hey folks

i did this render yesterday with the render settings of Emil3D’s classroom scene.

I am quite happy with the result (render time 19 min. on my particular system) but there are to issues wich I recognized:

In the red circle on the bottom of the table I think it looks quite unnatural, because there are no shadows of the table legs.

Also the floor shader has a bit reflectivity (like the floor in Emil3Ds classroom scene) but you can not see any reflections.

If you have suggestions share it with me :slight_smile:

All materials mia_material

thanks

Cu

Dominik

#11

Just render an ambient occlussion pass and your legs should look fine. Great image!!

#12

Are you sure all objects have ‘Visible in Reflections/Refractions’ flags set to ON? When importing objects, with some maya versions and certain import formats (.obj) these flags are set to OFF by default.

#13

you need to increase the number of rays in 4 places:

  • light shadow rays (light options)
  • shadow rays (render globals)
  • raytrace reflec/refrac rays (render globals)
  • FG reflec/refrac rays (render globals)

add an ao pass for more shadow details.

#14

Awesome render. Just some constructive comments:

  1. The couch looks a bit CG-ish in places - almost like the FG is too spread. An AO pass would also add some shadow detail between some of the cushions where it’s too soft. Some parts look perfect - like the right hand cusions but the shadows under the “sitting” cushions need more shadow detail.

  2. The corner where the walls meet looks unnecessarily occluded. This is quite standard result though with FG and GI - I think it’s something to do with the falloff or spread of the FG occlusion but I’m not sure how to fix it as I haven’t played with GI and FG since 6.5.

Can anyone suggest how one would get less of a spread / softness with regards to the occlusion because I think this is where FG starts to look a bit unrealistic. I realise this softening and spread is to help reduce flicker but how does one change the spread - radii perhaps?
Try a test render using amb_occlusion (no FG) and then the same scene with FG_occlusion (with default FG settings) and you’ll see what I mean. What needs to be tweaked to find the happy medium between render time and better occlusion?

#15

Hey guys,
thx for your replies.
@hkspowers
Yes, i thought about it before, but I would like to have it in the normal render also :-).
I also used already the built in ambient-occlusion in the mia material

@floze
‘Visible in Reflections/Refractions’ is on, because I modeled all models from scratch and didn’t import any objects.

@royterr
I cannot increase light rays, because I only use Mr sun/sky, and in the direct light options there are no shadows enabled (if I am not doing wrong now)

Raytrace reflec/refrac rays and FG reflec/refrac rays have already been increased.

I think I only forgot the shadow rays, but I am not sure now, I have to check it later at home…

@modernPrimitive

Yeah, you are right. I think the problem is that I used mia built in ambient occlusion with the sofa and the walls. I’ll try to switch it off and render seperate mib_ambient_occlusion layer.

It was quite hard to lay out the uv’s of the sofa, because I am such a noob in uv’s and I think I did it not perfectly or not in the right way… but I will fix it :slight_smile:

So I will try to improve the whole scene, remodel some objects to get it more realistic (like the strange lights :-)) and add more objects…

see you soon - very good thread (Emil3D)

Thx

Dominik

#16

hmmm…and now for some animation…

We’ve just done an interior animation with an animated sunrise to sunset. Still getting some artifacting, which we’re partly cleaning up in post but it’s approaching acceptibility.

Res: 1000x500
Rendertime: 4min per frame on an AMD X2 3800

Will link to a clip sometime when we’ve tweaked a bit more…

#17

Hey,

I did the image below now with occlusion pass…
A lot better I think, but I get the shadows under the table back (caused by the glass surface, which I wanted to get rid of it by increasing the fg rays in refraction).

I could probably avoid that by not affecting the glass surface by occlusion shader - I will give it a try these days…

There’s still a lot to do - increasing the fg point size to get rid of the speckles, for example…

I could unfortunately not use the ctrl_occlusion shader, because it is not compiled for a 64bit system. That’s a pitty!!!

Ok, thx for viewing and posting comments and critics

Cu

Dominik

#18

Hi folks,

some update with sky multiplier 1.15 and some reflections…

I am not perfectly satisfied but it is going in to the reight direction

Cu

#19

MrHoo
Nice scene, I’ve been following this since a while
What really catch my eye is your sofa model… it looks so real !
So I was wondering if you can tell me your method of making the bump map for the cushions…and also did you used a mia_material ?

keep updating, looking very good

#20

Hi myself44,

I used a fabric texture (I think from cgtextures.com) for the bump, which I repeated several times and yes, I used mia_material. Actually all materials in the scene are mia_materials…

I am not satisfied with the floor. I want to achive realistic ceramic-tile look, but it works not perfectly. I have got a map in the refl_color slot and another for bump, but I get this speckle reflections. I have to tweak a lot more I think…
Time consuming…
So if anybody has got ideas for cool realistic stone (ceramic) tiles, like bump mapping and refliction mapping workflow, share it with me please :slight_smile:

So, I’ll will add more items like pillows, shelves and so to the scene soon.

Stay tuned

Dominik