Lookdev Master Class with Elvin Siew
My first post for a Lasalle College of the Arts Animation Masterclass Series!
Elvin Siew is currently working in the lookdev department at ILM Singapore doing UV unwrapping, texturing, hair grooming, shading and some shot assembly/rendering.
Here is a brief summary of what he covered:
1) Deconstruct the surface, identify material of asset.
2) References – devianart, morguefile, flickr, cgtextures, mayang, texturearchive, texturepilot, environment-textures, 3d.sk (not free)
3) Shader – Diffuse, Specular, Spec size (roughness), bump, displacement
4) In the industry, you will be handed a concept painting (sometimes) and some images ripped off google to give you an idea of how the character/creature should look like. What you need to do is to find high resolution images to start your texture painting. Be observant about the color variations. Example reference: Neil Blevins website.
5) First question to ask: How big will the asset be on screen? It will decide how you unwrap the UVs. Usually you would want to have a map double that of what is rendered on screen. Keep to square formats for efficiency.
6) Figure out the seams of your asset for the UV map. Elvin’s way of unwrapping UVs is to find a large flat area to project planar, then select the seam edges, cut the UVs there. Unfold (with unfold constraint horizontal) and relax, and repeat for parts of the map that are too tight. Use the interactive unfold sliders to do it really fast. If the solvers doesn’t give you desired results, you might just have to move the UVs manually. Align the straight outer edges of the UV map so that square textures sit in nicely at those parts (for cloth only).
7) Another way of unwrapping UVs is to modify your model by smoothing it out (average vertices), then unwrap it and transfer the UVs back to the mesh using topology space in the option box.
8) When painting textures, source as much references as possible. Start with the color map. Block out the base color with a custom brush that matches the tonal patterns of the material. Use color channels from reference photos to extract nice patterns that resembles the asset to paint color variations on the material. Further fine tune it by painting a mask for each layer.
9) Use filter > Other > Offset to make a tileable texture in photoshop. Check wrap around. Then blend the mid points with the clone brush (custom hard brush, 100%).
10) You can use TextureFrank to check your tileable texture.
11) For bump and spec maps, we can duplicate the layers that we have for the texture and control each layer’s brightness. We might want to reduce the frequency of details. An alternative way if we do not have layer control is to use the high pass filter for the bump map which is quick and easy but not as high quality.
12) To assign more resolution to one mesh, we use multiple UV tiles. Make sure each of the UVs does not go beyond the 10 units grid. The old way to do multiple materials on a single object is to use the layered texture shader (blend mode add) where we have to translate the various U and V values to match each UV shell and setting the default color to black on each file node. Elvin’s suggested way is to use the same offset method for the UVs but to chain up the file nodes through the default color attribute instead of plugging them in to the layered texture shader. There is a script to automate this.
13) Use color management in your renders so as to best match a live action plate if it is a VFX project. Set default input to sRGB so that our color maps will be read correctly. Using this method, we have to additionally set the color profile of our bump and specular maps to linear.
14) Use mia_material_x to achieve the look of most materials.
15) For skin, use the misss_fast_skin shader. Plug in the respective maps – diffuse color (desaturated, yellowish tray), epidermal (photo real), subdermal (red tint, blur), specular map, normal map. Elvin added an mib_ambient_occlusion to the overall color and tinted the dark color slightly red so as to fake a small additional darkness to the lips and eyelids to kill off the “waxiness”.