Mental Ray Rendering Issues (Maya)

pliang

So far when it comes to rendering using mental ray I found out that objects (In Maya) only shows when there's no skybox obstructing the way...however I am currently working on a world right now and I need a skybox to go with it.

I'm using an High Dynamic Range Image map for the light source but does anyone know a more appropriate setting for mental ray to render without it? I've only used that method so far and as far as I have tried for myself, everything renders out pitch black.


Lemme know.

pyromania

For your skybox shader, do you have the file texture's outColor linked into the skybox shaders ambientColor? If you are using final gather you can light the entire scene using nothing but the texture on your skybox.

pliang

OK, have to look into that which I dont know where to start, I actually haven't tried something like that in the past so no idea what you're saying except the prolly having something to do with in the connection editor.

It'd be great if you tell me the little steps though.

And no, my skybox is juts a dome shape by itself with the default assigned to it as of now.

pyromania

Ok, when you said skybox I figured you had a large cube surrounding the entire environment that had a sky or backdrop texture applied to it. If you have a cube or sphere surrounding the whole scene you can use the texture on it to light the scene. You will either get true HDR lighting if you use a real HDR image, or fake-HDR lighting if you just use a normal texture.

Create a cube or sphere that surrounds the whole scene.

Create a new lambert shader in hypershade. Create a new file texture node and load your HDR image or sky texture.

Connect the outColor from the file node to the color and ambientColor attributes of the new lambert shader. You can do this in hypershade.

Apply the new lambert shader to the box or sphere surrounding the scene.

Now in your Render Settings turn Final Gather on in the mental ray tab. To get a good result you should increase the number of Final Gathers Rays to something like 500. You can play around with this value until you find a result you like.

Render scene.

pliang

Thanks for the info, I'll give it a run.

pliang

Alright so I did the following and from the results one thing for sure is that my HDRI image was too bright for it and the one using the texture looks better but really dark overall...if I finished texturing the environment and did the same to the other shaders would that help illuminate the scene?

Here're the results - The first one's using a featureless sky texture map, the one below is using the bright HDRI map.


Lemme what else I can do on the first one to make it better lit.

Thanks

pliang

I would also like to specify the settings I used in Mental Ray as it's one of the crucial steps...

I used raytrace shadows with default settings.

I used 600 rays for final gathering.

I used adaptive sampling with min sample at 1 and max sample level at 3

Other tabs under ray tracing was turned off or to low settings (i.e reflection level, refractions) except shadows.

Before all this when I was getting pitch black results, I used the same settings but used the hdri map as an environment map.

aesir

I cant help you at all with the MR issues, but I really liked the enviro so i wanted to throw in some compositional ideas.

Put a plane as close to the camera as realistically possible in the top left corner, probably just the front end of the plane. Whatever looks good.

And add a point of interest like a tank or an explosion at the end of the long street.

pliang

Yep, I actually do have a tank in there but I used an older version of the scene for ease, good ideas though however.

pliang

So now I've done texturing everything in the scene and generating diffuse, bump and some normal maps as of now but does anyone know a good way to generate smoke besides faking it with billboards?

Keg

there is maya's fluid setup if you have that, but that's not really game orientated. other way would be particles

pliang

ic...unfortunately I've never touched those before, I'm gonna have to check that out later or perhaps later on recomp it with after effects. I was thinking of making a 10 sec short clip of the scene with animation in it so by then I'll try those out.