Bump Displacement Map Workflow
Maya: Mental Ray
Normal Bump and Displacement Maps are extremely useful for geometrical details (bumps, dints scratches, scales, warts, pores) on environments, objects, animated meshes. They are also useful for general scene management and optimisation.
All methods require the mapping of sculpted/painted detail onto low resolution (base) meshes for deformation, animation and rendering.
We can use the 3 map types, bump, normal and displacement. Each has it’s own advantages and disadvantages….
1. Bump Maps: Easy to paint fake for very fine details. B&W Map
2. Normal maps: Best fake solution, used in games or fast to render, no change to silhouette. Hard to pain, usually sculpted or converted. Coloured maps. Tangent Space Normal Maps are blue/purple and are the best solution for characters.
3. Vector Displacement Maps: Projected accurately using tessellated meshes at render time (most accurate but slower renders) Vector displacement (coloured maps) have the advantage over B&W displacement that it can displace concave surfaces. We also use the “absolute tangent space” for most objects in MR, this type supports deformation.
We can still use black and white displacement to extract height map information for other textures. This is useful in some circumstances for diffuse, specular and even bump etc.
What Are Bump Displacement and Normal Maps
When to Use Bump Normal and Displacement Maps
– Bump Maps are handy for very fine detail, they are easy to paint and are handy in situations where poly counts on sculpts get ridiculous
– Normal Maps are fast to render and are created by baking sculpted detail, they are superior to bump maps. Use when displacement isn’t necessary
– Displacement Maps are used when it’s important to have all the details render correctly and be seen in the silhoette. This is perfect quality and can match sculpts exactly, but require extra time to render correctly so are usually used on foreground objects or big chunky detail.
– Sometimes it’s best to poly model details. Extact when to use modelled detail or maps is customisable and depends on a lot of criteria. Usually what method is easier to produce and render given quality at the screen resolution of the final product?
Matching Maya UVs in Mudbox
Bump Maps in Mudbox
Important: Exporting Bump Information to Maya Note
Mesh Preparation: Matching Subdivision Smooth for Mapping Sculpts
– Mudbox subdivision surface algorithm matches Mayas
– Match subdiv levels on the base mesh and sculpt so only the difference is mapped
– Use same meshes/vertex counts where possible so subdivision methods can be used in the extract
Sculpting With Sculpt Layers For Later Use
Creating a Height Map For Other Textures with Displacement
Mudbox: Extracting Normal Maps For SubD Base Meshes
– Hires sculpt mesh to Hires Base Mesh
– Use Subdivision where possible
– Use Raytrace and tweak the distance when intersection errors
– Blend maps in photoshop or paint out purple to solve issues
– 8 bit colour is normal
– for linear workflow be sure to make linear under texture image settings
Mudbox: Vector Displacement Maps For SubD Base Meshes
32 bit Vector Displacement Maps are the highest quality displacement map type. We’ll use absolute tangent space in almost every case. It should work for any type of mesh that uses subD’s.
* Note In Maya we’ll need to use the MR approx editor in Maya with the “Subdivision” Approximation type. And be sure to set the texture’s color profile to “Linear” if using Linear Workflow. (see other section below)
– Use Vector Displacement Maps at 32 bit colour, exr of tif is fine
– Match the same poly subdiv level for both the base mesh and the sculpted mesh… this should be level 4+ The displacement will calculates differences based after the smooth is applied, since we’ll be smoothing the base mesh in Maya.
– Target Models (use the base mesh with a high smooth level… be sure to change the levels to highest here)
– Source Models (use the sculpted detail mesh)
– Smooth Target Models (off)
– Smooth Target UVs off for MR (on for Vray, Renderman)
– Use Crease and Hard Edges: Off unless you’re using ceases
– Smooth Source Models off
– choose your image size and antialiasing quality (go high for final quality lower for testing)
– Vector Displacement Options (these settings will need to match mayas in the MR displacement node)
– Absolute Tangent: The one we use most often for deforming meshes
– Relative Tangent: For mudbox stencils etc
– Object: Can use for spinning objects which don’t stretch and deform ie meteor
– World: If the object doesn’t move in the scene
In Maya to match remember to use “Subdivision” Approximation and tweak settings (other section) in MR and switch the texture type to “linear”
Sending To Maya
MR: Assigning Displacement Maps In Maya
1. find the shader and assign it to geo
2. select the “shading group” connected to the shader, this is not the shader, find the “shading group”!
3. map into the displacement slot of the shading group
4. on the displacement node detach the file from the displacement slot
5. map a new file texture to the vector displacement slot
6. make sure the object and it’s groups are frozen transforms to 1 of scale
7. on the file texture if using tiles set to mudbox
8. on the file texture colour profile set to raw
9. the file should render but will be slow. (this is using maya displacement not mental ray) And might not look super awesome.
Right now the map is setup for Maya but not Mental Ray.
10. MR setup. Setup approx editor to optimise render times and better quality (mental ray displacement)
MR: Maya Approximation Editor for Displacement
In Maya (from Mudbox) once the displacement map has been applied we can render and see our object. However MR is having to convert the maya style displacement.
The maya style (not MR style) is very inefficient and takes forever to render. It’s much better to use the MR style displacement as there will be less artifacting and seams are better too.
To do this use the Approximation Editor…
Window > Rendering editors > Mental Ray > Approximation Editor
Select the model and hit create in the approx (usually subdiv method not displace).
Subdivision Type is used if the object is Subd’s (3/ctrl alt 3 smoothing).
After creating the Approximation you can find it by selecting the mesh and it’s in one of the mesh’s tabs. Approx is mesh based, so you need to put it on all models with displacement.
Find the approx on the mesh in the attribute editor then…
Switch to spatial type for good results in the drop down
“Spatial” uses a smart algorithm which speeds renders times up significantly without loosing quality. Tech terminology is that it uses “adaptive tessellation” for rendering efficiency.
Brief description of Spatial settings…
Length: Defines the triangle length for calculating how detailed the poly counts are (also this is clamped by the max and min subd levels). Usually start at 1 with the “View Dependant” chekbox on. Lower values show more detail and are sharper, but there’s a limit to how small you can go.
View dependant: (checkbox) switching this to on makes the length relative to pixels. Length becomes pixel length, not world length (cms or mms). Pixel length may cause some artefacts in animation. But should be barely noticeable if used correctly with setting
“Length” below 1 (pixel).
Min Max: The min and max subdivisions act as limiters. How many times can the mesh be subdivided at it’s max and min levels? Remembering the subdivision levels are smart depending on how far from camera and depending on the length settings.
Sharpness: Will help maintain the sharp square look if desired it’s quite subtle.
Approx style fine: (checkbox) Get lots of detail and is efficient style. I usually switch this on.
Suggested Approximation Levels in MR
1. Approx > subvision > create
2. Switch Spatial Type (found on the mesh in the attribute editor)
3. Checkbox view dependent on
4. checkbox fine on
5. Length 1
6. Render and adjust the length to suit you, the smaller the number (not 0) the sharper the displacement. 0.5 gives heavier render times but nice sharp displacement.
Maya: Mixing Bump or Normal and Displacement Mapping
Maya: Mixing Bump and Normal Mapping
Converting Bump Map to Normal Maps