Adding detail with alphas
The process was something like the following:
Model a shape that you want to use as alpha in ZBrush and export as OBJ
Import it to ZBrush, place it in the canvas and then press 'T' to drop the tool
Click In the brush palette and choose the MRGBZGrabber brush
With the MRGBZGrabber brush selected, click-and-drag anywhere on the canvas until it covers the whole canvas. When you release it, ZBrush will capture and store color and ZDepth information from the canvas
You will find the ZDepth information in the alpha sub-palette. Select the alpha and export
Open it in Photoshop and adjust the document size to be square
Using custom-made alphas to add detail
With the high-res retopology done, I imported all the pieces back into ZBrush as separated SubTools for final detailing and polishing. I used the alphas I created and also, with the Standard brush, I added some folds on the fabric and rubber areas.
Polishing the sculpt and adding final detailing
From the beginning I wanted this to be a character for a game, so once the high-res model was done, it was time to work on the game model. At this point the process was very similar to the 'High-Res Re-topology' step.
I again used Decimation Master on my high-res model to get a lower polygon count version (1). Then I could import it into Maya for the re-topology, but this time for the game-res version, something around 15k to 20k polygons (2). Once the re-topology work was done I then split the model into a few parts which each one could have their own UV sets and textures – head (yellow), hair (red), eyes and teeth (green) and body (blue) (3).
It's important the break the materials up like that because you want to be able to control the material properties and resolution independently from each other, especially the head since it is usually the focal point of the character.
Converting the high-res model into a games version
Another thing to take in consideration here is the facial topology. It's important that the loops are placed respecting the face structure, muscles and so on. That will allow the face to have a better deformation when animators are working on the face expressions. Although that wasn't the goal here, it is always a good practice to do them.
Textures were pretty straight forward. Normal map and occlusion map were baked with xNormal
. Cavity maps were extracted from normal maps in Photoshop with a personal set of actions, but you could get it with the xNormal filter for PS or nDO. For the face I used real photo reference projection in Mudbox
Working on the topology of the face
To give the character some attitude in the final render, I decided to pose the model just like the concept. For that I imported game model back into ZBrush and used the transpose tools.
The process of posing is as follows:
Mask out the portion of the model you want to pose
Select the Transpose Rotate tool and place on of the ends of the transpose line at the desired pivot point
Click-and-drag the other end to rotate and pose the unmasked portion
Using the transpose tools to pose the model in ZBrush
I basically followed these three steps to pose the whole body. It took some back and forth, masks, touch ups and right placement of the transpose tool to get everything correctly posed but it was, definitely, much faster than the traditional way of rigging.
To render this character I used Marmoset Toolbag
. It was really good because it gave the model that in-game look since it's pretty much a game engine. But before taking the model to Marmoset, there are a couple of things that you need to do when exporting the model from Maya to Marmoset.
Make sure you split the model based on the UV sets, and name them accordingly to each object for easy management later, then make sure you select them all to export at the same time
Then go to File > Export Selection. In the Export window, choose OBJexport as your file type and make sure Groups is turned on. This is important to guarantee that the model will be exported as separated objects instead one object together
Importing it into Marmoset you will get a list of chunks that match the objects exactly in Maya, and then you will be able assign one material for each one of them
The process of rendering in Marmoset Toolbag
After I was done assigning all the materials, with the correspondent textures, I made a quick a lighting setup. First I chose Garage in the Sky Lighting Presets (1) to use as my global lighting. Then I added a couple of dynamic lights (2), one over the head (A) to slightly illuminate the face and another far on the side (B). After that it was just a matter of placing the camera, adjusting the field of view, which in this case was pretty low, 15.00, and rendering it (3).
Adding a lighting setup to the scene
With the mask in the alpha channel of the rendered image, I could easily isolate the character from the original background (A). I added an occlusion pass in Multiply mode to give it a little more shadow information (B). Then I created a simple background in Photoshop that matched the lighting in the render, painted some ground shadows (C) and added some layer adjustments to tweak the color and saturation to get my final render (D).
Compositing the final image
The final render
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