Mental Ray

Physical Sun and Sky and Linear Workflow /  by Xuan Prada

  • First of all activate Mental Ray in the Rendering Options.
  • Create a Physical Sun and Sky system.
  • Activate Final Gather. At the moment should be enough if you select the Preset Preview Final Gather. It’s just for testing purposes.
  • Check that the mia_exposure_simple lens shader has been added to the camera. And Check that the gamma is set to 2.2
  • Launch a render and you’ll realize that everything looks washed.
  • We need to add a gamma correction node after each texture node, even procedural color shaders.
  • Connect the texture file’s outColor to the “Gamma Correction” node’s value. Then connect the “Gamma Correct” node’s outValue to the shader’s diffuse.
  • Use the value 0.455 in the gamma node.
  • The gamma correction for sRGB devices (with a gamma of approximately 2.2) is 1/2.2 = 0.4545. If your texture files are gamma corrected for gamma 2.2, put 0.455 into the Gamma attribute text boxes.
  • If you launch a render again, everything should looks fine.
  • Once you are happy with the look of your scene, to do a batch render you need to put the gamma value of the lens camera shader to 1.
  • Under the quality tab, in the framebuffer options, select RGBA float, set the gamma to 1 and the colorspace to raw.
  • Render using openExr and that’s it.

Dealing with normal maps in Softimage /  by Xuan Prada

Yes I know, working with normal maps in Softimage is a bit weird sometimes, specially if you worked before with 3D Max normal+bump preset.

I’ve been using the same method over the years and suited fine for me, maybe would be useful also for you.
I prefer to generate the normal maps inside Softimage rather than Mudbox or Zbrush, usually works much better according to my tests with different assets.

  • So, you should import in the same scene both geometrys, high and low. Don’t be afraid of high poly meshes, Softimage allows you to import meshes with millions of polygons directly from Mudbox or Zbrush.
  • With both meshes in your scene be sure that they are perfectly aligned.
  • Check the UV mapping of the low resolution mesh.
  • Select the low resolution mesh and open the ultimapper tool.

- The most important options are:

  • Source: You have to click on your high resolution mesh.
  • Path: Where your normal map texture will be placed.
  • Prefix: A prefix for your texture.
  • Type: You can choose between different image formats.
  • Normal in tangent space: The most common normal map type.
  • Resolution: Speaks for itself.
  • Quality: Medium it’s fine. If you choose high the baking time will increase a lot.
  • Distance to surface: Click on Compute button to generate this parameter.
  • Click on generate and Softimage will take some time to generate the normal map.
  • The normal map is ready.
  • Hide your high resolution mesh.
  • Grab one of the MR shaders and drag it to your mesh.

- Use a normal map node connected to the bump map input of the shader.

  • Choose the normal map generated before.
  • Select the correct UVs.
  • Select tangents mode.
  • Uncheck unbiased tangents.
  • Hit a render and you’ll see you normal map in action.
  • Cool. But now one of the most common procedures is combining a normal map with a bump map.
  • I’m using the image above.
  • If you use a bump map generator connected into the bump map input you will have a nice bump map effect.
  • Find below the final render tree combining both maps, normal and bump.
  • The first bump map generator has two inputs, color matte which is a plain white color and the normal map with the options which I already commented before. Be sure to select relative to input normal in the base normal option of the bump map generator.
  • The second bump map generator is your bump texture where you can control the intensity increasing or decreasing the factor value.
  • The vector math vector node allows you to combine both bump map generators.
  • Connect the first bump map generator  to the first input and the second one to the second imput.
  • In the operation option select vector input1 + vector input2.
  • Final render.