Advanced Skeleton Tool Installation
After installing the advanced skeleton tool, I setup a new project file and referenced my model mesh from the old file. When the model was referenced into the new file I noticed that the colours of the mesh were dark, despite the use of lights being turned off. I noticed that the colour management settings were different to my old file, and later learnt that the old settings had been dropped in the newer versions of Maya. I switched the colour management settings from ACES to unity neutral-tone map to get similar colours to the referenced file. The colours weren't exactly the same, but this was something I would later deal with.
Refining Mesh Topology and Textures
Before I begun the rigging process it was clear to me that there were some changes that needed to be made to the mesh. It became evident to me that when the characters arms were lifted up, there were segments of vine that were protruding.
I remedied this issue by pushing the geometry inside of the stone. This made for a much more subtle end to the vines.
I also made some slight changes to the head geometry. I made the eyes more oval so texture stretching wouldn't be as noticeable for when the mesh is deformed when blinking.
The initial topology of the head was not ideal and wouldn't have deformed well if the facial rig was applied.
The image above is the reference that I used for retopology. I started with low poly shapes to make it easier to identify the different areas of the face. This made it easier to create more edge loops later that helped further define the topology.
After the retopology process I smoothed the mesh to create more geometry for higher quality facial deformation.
Following the same process as assessment one, I unwrapped the new mesh and replaced the UV shell of the old head in the UV map. I made sure to orient the new shells the same way so that I didn't have to retexture the head from scratch.
The new UV shell placement meant that I still had to make small adjustments to the texture in Mudbox. Afterwards I also generated a bump map using the new texture.
Body Rigging and Skinning
After the final adjustments to the mesh had been made, it was time to rig the character. I loaded a biped fit skeleton preset from the advanced skeleton tool. I deleted any of the joints that didn't apply for my character and aligned the remaining joints with the mesh.
On each of the joints I adjusted the fat weights so that when the joint controllers were generated, they were approximately the correct sizes. I wasn't too concerned with getting these correct straight away as the controllers could be resized whenever.
After generating the advanced skeleton and joint controllers I checked to make sure everything fit properly and was symmetrical. Once I confirmed this I used the pole vector check box to identify what direction the elbow and knee joints were bending. The direction of the knee joint was incorrect so I adjusted this by moving the knee joint forward to create a slight bend in the intended direction.
Next I needed to bind the rig to the mesh. I decided upon 'option 2' which makes use of a skin cage to apply skin weighting. I knew that this wouldn't create ideal skin weights for this particular mesh. This didn't matter as I would have to fine-tune the weights for my mesh regardless of the initial method.
Skinning the stone and foliage objects was simple, I just made the joints have 100% influence over their matching mesh segments.
Skinning the vines proved most difficult throughout the skinning process. It was challenging to make the vines deform and stretch realistically. I found the whole process was a lot of trial and error with blending the skinning along the vine in different areas. The advanced skeleton animation tools proved extremely useful for testing joint rotations quickly and efficiently.
I found the wrist was especially difficult because the vines had to rotate in all directions without weird deformations. This made it impossible to use uneven influence to counteract the joint bend direction.
Some of the vine geometry was clipping through the stone when bent on a couple of different joints. The knee in the image below was particularly troublesome and kept clipping into the stone no matter where I blended the weights.
This is most likely due to the lack of edge cuts in the mesh. Making use of one of the techniques in the image below would have assisted with a cleaner deformation. In hindsight I should have also taken the position and direction of deformation into account when creating the interwoven vine mesh.
Calisthenics test Playblast
I generated calisthenics animations using the animation tester provided by advanced skeleton. This allowed me to easily rotate all the joints separately by 90 degrees. I then exported a playblast animation that can be viewed below.
After reviewing the playbast, I noticed that some of the finger joints had slight influence over parts of the arm and wrist. I went back and fixed these issues using the colour ramp option to help identify areas of low influence.
Facial Rigging and Skinning
Rigging and skinning the model's face was definitely the most challenging component of this assessment. This was mainly due to the design and style of my stone golem. When I began applying the fit skeleton for the mesh, there were 2 major issues that I had to deal with. My character didn't have any nose or eyeball geometry. This was a major issue because the advanced skeleton face setup required inputs for these, otherwise the build process would fail.
Due to time constraints I was not able to go back and sculpt a stylised nose for my character. To complete the fit skeleton nose selections I decided to select vertices around the same location the nose would be. This would allow me to complete the selection process and complete the build with no errors.
I wanted my golem's eyes to remain the same, as I liked the cut-out design of them. However, the advanced skeleton tool requires eyes for the facial rigging process. I worked around this by updating my model to include eyes, but applying an invisible material to them. This solution allowed me to keep the stylised stone cut-outs for my model's eyes.
While I was moving through the step-by-step build process, I was worried about how the eyelids would look upon closing. Due to the stylised nature of the eye cut-outs, I was concerned with how the tool would handle rigging and skinning the blinking. To my surprise, the blinking was quite clean but there was a lot of texture stretching initially. I was able to slightly reduce this by adjusting the 'blink center' variable, which reduced texture stretching on the upper eyelid.
After I had completed the face setup, it was time to create blend shapes for the 7 universal facial expressions. I wasn't able to remember what all 7 were, so I used the reference image below to assist me.
When I begun to create the blend shapes I realised that the latest version of advanced skeleton comes with 7 of these blend shapes already built-in. By clicking on the smiley face control box, there are variables for each of the 7 facial expressions. This gave me a solid foundation to build upon for creating my blend shapes.
While I was editing the blend shapes I realised that the grass beard did not follow the jaw when it was opened. This was strange because I included it in the setup and it should have been weighted correctly during the skinning process. Due to time constraints I thought it would be easier to just remove the grass beard objects from the reference model. If I had extra time I imagine this issue could have been fixed by editing the skin weights on the jaw to include the grass.
Final Adjustments
There were a few lingering issues that I mentioned earlier that needed to be fixed. The joint controller sizes and rotations needed to be adjusted so that they were easier to interact with. In addition, the texture colour balance needed to be tweaked because the new colour management settings changed the display colours. These were quick and easy adjustments that made the posing and rendering process a lot smoother.
Posing and rendering
When posing the character it was recommended that the contrapposto pose was used. I thought this exact pose wouldn't really fit my rock creature, so I decided to create a variation based off the concept behind the pose. Creating direction and weight on one leg was vital for a good pose.
I started by creating a new file and referencing the rig and model. I did this because I wanted to keep the model, rig and final scene in separate files for a cleaner workflow.
When creating my final scene and pose I wanted curiosity and exploration to be the dominant feeling throughout the renders. I created a firefly-like light and positioned it in the model's hand. I then created a facial expression of wonder by adjusting the surprise and fear blend shapes.
Final Renders
References
Advanced Skeleton tutorial by AdvancedSkeleton: https://www.youtube.com/watch?v=mTB9Yh_sWKc
Joint Placement Tutorial by Academic Phoenix Plus: https://www.youtube.com/watch?v=Qmn9BWdqYhI
Face Setup tutorial by AdvancedSkeleton: https://www.youtube.com/watch?v=2dja2ilVDtY
Face topology reference image: https://i.pinimg.com/originals/49/57/f8/4957f81348053be65a33ee8cdf95a9f4.jpg
Retopology tutorial by FlippedNormals: https://www.youtube.com/watch?v=xpDWta5O3n8
Advanced Skeleton documentation: https://sites.google.com/a/animationstudios.com.au/animationstudios-com-au/advancedskeleton/help/4-bodysetup
7 universal facial expressions: https://www.apa.org/images/PSA-2011-05-matsumoto-fig1_tcm7-115934_w1024_n.jpg