Mental Ray - Shaders


#4641

Cheers Flavio,i might just send him an inquiry as i’m having terrible results trying to achieve the elusive Silver car paint.


#4642

This is my first real attempt at serious MR shading and lighting.(with a great legup from JP’s vid tut)I have a few problems that i wondered if anyone had any advice.
On the image below: the brake discs and tire sidewall have bump mapping applied but no matter what i seem to tweak i can’t seem to get a crisp result. I thought it might be an issue with reflection settings but i’ve tried so many different settings that i’m sure i’m wrong.
The maps are pretty highres and test render fine if i apply them to the diffuse component.
The render below has pretty high settings all round.

Also,on a sidenote, does anybody know what that weird banding is that runs across the BG image? I can’t seem to get rid of it.Even if i just render it as a regular BG environment map with nothing else going on in the scene it shows up.

any input would be greatly recieved,cheers.


#4643

The banding is the arial perspective turned on in the physical sky. Just turn it off.

Fot the bump mapping, try turning the blur settings to like .1 or .01 in the map rollout.

Nice render !

Regards,
Mike


#4644

Mike is right set the blurring somewhere below .6(you may need to go as far down as it will go-.01 in some cases), and for bump maps I usually use summed area filtering.

Todd


#4645

Cheers Mike/Todd.Great to see the banding gone but unfortunately, turning the Blur amount down just made it even sharper.Is this a common issue with bump maps in MR?

i also tried summed area filtering.No joy.

Thanks.


#4646

Here’s another example of strange artifacing with bump maps.As you can see in the viewport the UV’s are pretty good.Note the weird black patches on the collar area. This dosn’t show up in the render if i disable the bump map component in the material. Has anyone else experienced similar issues pertaining to bump maps in MR?

EDIT: in the case of the shirt it was a Normal map causing the issue.

Cheers.


#4647

Jeff,i was just wondering what method you used to setup the LDRI light probe that you’ve used in your vid tut? did you just map a sphere with the background image, render it and crop in PS? If so,is there any particular material/light settings to be aware of?

Cheers.


#4648

Afraid I don’t fully understand the question. Are you asking about the creation of the light probe itself or how it’s implemented in the scenes?

If it’s about the actual probe creation process: I used a “christmas ornament on a stick” for that particular setup:

I tried to zoom in as close as possible to the reflective ornament. I then cropped the image to get a full frame image of the probe.

FWIW all that was prior to purchasing a fisheye lens for my camera that I now use to capture full 360 degree HDR panos:

If you’re asking about the actual scene setup, the scenes make use of the mental ray production shaders (the scenes should have been included with the video). To be more specific, the probe was used in the mirrorball shader.

If I’ve misunderstood your question, I apologize. Please feel free to PM me and I’ll dig out those files (I don’t have them here on my current workstation) and try to provide a more specific answer.


#4649

I am wondering if it is possible to increase/decrease the color bleed from the AO settings in the A&D material. I would like to be able to increase this. I tried outputing the AO render element with color bleeding enabled in the A&D mats, but it is still just black and white. Any suggestions ?

Regards,
Mike


#4650

I think that AO is limited to black and white. Colorbleeding with MR occurs through the FG process or with photons. Within both you can use a multiply to increase or decrease the effect. Ctrl_studio had developed a “direct occlusion” shader which is supposed to shade color but I haven´t any experience with that. Google for “ctrl.occlusion” shader.


#4651

The render element “mr Xtra Diffuse Indirect Illumination with AO” will give you an AO pass that has the color information from the AO color bleed built into the A&D material.

To try and further control it, I was just playing around with putting an Ouput shader in the Shadow Color slot. The results are interesting. Not sure how useful, but interesting. Setting the Output amount or the RGB Level to a negative value certainly increases the intensity of the colored AO, but also brightens it up to a neon glow.
Not sure how useful, but interesting.
No more time to experiment tonight.


#4652

Hi musashidan,

In that example I used a Shellac blend between two Arch & Design materials. The lower layer was a blurred A&D, while the upper was a clear coat style reflective laquer. Just testing. Don’t actually use it for anything. Doing a lot of calculations to render.

But I have found that the simple Car Paint material, when tweaked, offers good results for silver paint (see below : Car and wheels both use different setups of mr Car Paint). Much quicker at rendering too. You just need to give yourself a bigger, softer specular flare/bloom, and adjust flake sizes.

You can also set the reflections to blurry, or the flake reflections too with the Car Paint shader if you want a more soft, diffuse reflection.

As Jeff has shown. It ALL depends on the environment you are reflecting and the lighting. I love my 180 fisheye lens (and PTgui) for catching and creating HDRI environments, though mine are not all sunny US scenes :wink:

Dave


#4653

I posted this in the area, but thought this forum may be more appropriate - anyone having similar issues with car paint material in 2010?:

When using a car paint material in MAX 2010 (SP1), I’ve found that the specular reflection parameters for specular 2 don’t seem to work anymore. In MAX 2009, I can tune a nice sharp white highlight with specular 1 parameters to simulate a clear coat, then using specular 2 parameters tune in an underlying soft-edged colored highlight to accent the less glossy paint layer beneath the clear coat. In MAX 2010, I can still get the white highlight with spec1, but then when I adjust spec2 parameters, the best I can do is produce a thin colored halo around the spec1 highlight, not an independent specular reflection like in MAX 2009. I understand there are other ways to create similar effects, but none as efficient as this handy material. Any ideas? Thanks.


#4654

I can confirm the different behavior.

While it’s not an answer as to why, I can also confirm that you can replace the paint.dll file in 2010 with the one from 2009 and get the same results between 2009 & 2010.

Just make sure you keep a backup of the paint.dll from 2010 just in case you need it later.


#4655

Thank you - then I’m not mental.

I was wondering if there was some dlo/dlu/mi swap I could try - I blindly tried a couple things with paint.mi and paint_max.mi between 2010 and 2009 that didn’t work, so thanks for the dll tip - works like 2009 now.

I also saw the blend with A&D idea a couple posts back, similar to what I used to do with raytrace materials… I might try that - sounds interesting.


#4656

Hi,
I have an exterior scene, its a night time scene with a lot of trees using cutout maps for the leaves. I’m lighting these trees with Area lights as they cast shadow onto the building and I need soft shadows. This combination is making render times are astronomical.
I’ve turn the blur down 0.01 on the cutout, lower the samples of the area shadows to 16,
Is there anything else that would speed this up ?
The Final gather speed isn’t to slow it’s the the AA thats killing render times.
I did see Jeff’s tip on freezing final gather map without the cutout and diffuse.

cheers


#4657

Probably you don’t need a leaf-by-leaf shadowcasting, since the shadows are soft and they will blend. So one possible thing would be to have a shadow shader with a much simpler map.


#4658

So a shadow map, not raytrace shadows ? like a gobo map ? Faux shadow ?


#4659

Nor really. Take a look at the mental ray material. You have a slot for surface and a slot for shadow, so you can put different shaders there. So you can make a cruder approximation of your diffuse/alpha map to plug into the shadow slot, that is still gonna give you the same results, because of the shadow softness.


#4660

Thanks Glacierise,
I plug a shadow shader into the shadow slot in the ARch&design shader.
Put the mask map in the transparency and blurred it a little, it worked a treat.
Faster rendering times just lots of prep to do each material.

cheers