Displacement Bump And Normals

Maya: Renderman

Info

This is Part Two of the ‘Mudbox Bump Displace And Normal Mapping’ course. In Part one we covered how to create Bump normal and Displacement maps in Mudbox, for a film/TV SubD workflow. Now we’ll see how we can apply them to Maya and in this case Renderman’s RIS renderer.

The workflow in Renderman is fairly straight forward, but there’s still a few things we need to know. Some things are not as intuative as we might expect.

Renderman is well known for having one of the fastest displacement algorithms in the business and in the newer RIS renderer it seems like displacement is still rockingly fast. This is great news as we can use displacement more than in other renderers with little slowdown.

The normal map workflow is also great and I love how you can stack normals and bump maps together which is more difficult to do in something like Mental Ray. Once we know a couple of little tricks then it’s a very easy system to use.

 

Mudbox: Quick Recap And Maya Project Setup (2 mins)

In the last class we went over the creation of displacement maps in Mudbox. The object has been slightly updated and completed surfacing all over. But the extraction process is the same. here we talk about exporting the maps to the Maya source images folder for hassle free texture workflow.

Video 1.1: Mudbox: Quick Recap And Maya Project Setup (2:14 mins)
 

Video Notes

Quick recap of lesson one and the saving of textures to correct directories in Maya and files structure.

 

Renderman RIS Scene Setup (4 mins)

Setting Up the scene in Maya for the RIS renderer in Renderman is very easy. Not much we have to do here, just remember to apply the Renderman geometry subd approximation.

Here we setup a standard outdoor scene with an Image based Light Dome (IBL) dome and directional light.

Video 2.1: Renderman RIS Scene Setup (4:06 mins)
 

Video Notes

Setting up the scene for lighting in Renderman RIS.

 

Renderman, Normal Map Setup (8 mins)

Normal Maps are fakes, so the geometry isn’t changed. Most obviously seen on object silhoettes. There’ll be more noticable distrotion the stronger the normal map effect. Still they are super efficient and require virtually no extra time to render. they are perfect for fine detail, and background objects. In games they’re commonly used throughout.

Fake effect normal maps plug into the shader. In the case of Renderman RIS they plug into the bump slot with a RIS normal node.

We can also see normals in the viewport, (Viewport 2.0) but the shaders will need to be Maya Shaders not Renderman shaders and the setup is slightly different but just as easy. Usually we can use render layers to manage the viewport and keep it seperate from the renderman shaders. But that’s for another topic.

Video 3.1: Renderman, Normal Map Setup (8:06 mins)
 

Video Notes

Setting up Normal Maps in Renderman’s RIS renderer.
*Note: In the current video I’m learning renderman so the video is a little convoluted. Setting up normal maps is easy. I also make a mistake when i talk about the Atlas Style attribute, this attribute is for UDM tiles, that’s when you’re using more than one texture map, in the case of Mudbox that refers to a UDM coordinate system, which is good if we’re using multiple textures from Mudbox.

Normal Map Steps
1. On the shader find the “bump map” slot, you can use normal or bump maps here.
2. Map a RIS > PxrNormalMap
3. In the filename slot of the PxrNormalMap find your file texture path
4. If coming from Mudbox check the check box… PxrNormalMap > Flip X

That’s it.

Maya fileTexture Node
If you wish to use a maya fileTexture node which has some extra offset and tile settings you can map a maya file texture to the “Input Normal” slot. But this generally isn’t required.

UDM Tiles
If using UDM tiles from mudbox (multiple textures) Use the setting
PxrNormalMap > Atlas Style > Mudbox

 

Renderman, Displacement Map Setup (12 mins)

Displacement maps physically change the geometry of 3d objects. So in the case of shaders and Maya displacement maps are applied to the Shading Group, not the shader. The Shading Group talks directly to the geometry in a scene, unlike shaders which are just material properties.

Setting up a displacement map in Renderman RIS is easy, but there are a few things to be aware of, epsecially in the optimisation of render times and selecting the correct displacement type.

Video 4.1: Renderman, Displacement Map Setup (12:43 mins)
 

Video Notes

*Note the seam in this video is caused by UVs being on the very edge of the 1-0 space. Best not to have that. A fix is to change the filter type of the images. In the case of a Renderman PxrTexture Node as used here change the

Setting Up the Displacement Map in the Renderman RIS Renderer.

APPLYING A DISPLACEMENT MAP IN RIS
1. Open Hypershade
2. Find the Shading Group of the shader select it in the attribute editor
3. Map a RIS > RMSDisplacement into the displacement slot
4. Inside the RMSDisplacement map a RIS > PxrTexture into the ‘vector displacement’ slot
5. RMSDisplacement > Scalar Displacement > 1
6. RMSDisplacement > Displacement Mode > Mudbox Vector
7. Map the file texture to PxrTexture > Filename
8. *Fix for this video change the filter type to PxrTexture > Filter > Nearest

Potential Problems And Solutions
Scale is too big or small:
– Check the object is has reset transforms, scale should be 1 and it’s parents also
Seam issues:
– Seams can be present in certain UV scenarios, because of the way maya smooths UVs
– UVs shouldn’t be directly on the edge of the UV space eg 0 or 1. Image filter types slightly blur values and can cause problems. See *fix above.

If still problems check mudbox export
– Check the Map imports correctly inside of Mudbox (see mudbox Export Map tute)
– Mudbox smooth UVs must be on with export
– Check export options of map inside Mudbox

 

Renderman, Bump Map Setup (7 mins)

Bump maps work in a similar way to normal maps, only instead of a colour image bump mapping relies only on a black and white map. This is easier to texture paint so is still handy for fine detail.

Applied to the shaders bump slot use a Renderman RIS bump node. Use bumps for fine detail. Or in mudbox as per the previous class we can create a normal map from a painted bump map. This can be applied easily in RIS too.

Video 5.1: Renderman, Bump Map Setup (7:33 mins)
 

Video Notes

Setting up a Bump Map in Renderman’s RIS renderer.
Bump Map Steps
1. On the shader find the “bump map” slot, you can use normal or bump maps here.
2. Map a RIS > PxrBump
3. In the filename slot of the PxrNormalMap find your file texture path

That’s it.

Maya fileTexture Node
If you wish to use a maya fileTexture node which has some extra offset and tile settings you can map a maya file texture to the “Input Bump” slot. But this generally isn’t required.

UDM Tiles
If using UDM tiles from mudbox (multiple textures) Use the setting
PxrBump > Atlas Style > Mudbox
Layering/Mixing Multiple Normal/Bump Maps
To layer in more normal or bump maps use: PxrBump > Input Normal

 

Renderman, Colour and Other Map Setup (1 mins)

This class has been focused on normal, bump and displacement. but obviously we can map regular channels too. This video shows the application of quick diffuse shader and the process is much the same for other slots. The correct understanding of how we can apply maps to various channels including specular and specular roughness is something that’s important to understand but it hould be covered in another class in detail.

Video 6.1: Renderman, Colour and Other Map Setup (1:56 mins)
 

Video Notes

Colour map setup and other.

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