As mentioned before, our dinosaur is to be created like a morph/plasticine look. After researching a bit further I came up with the following pipeline.
Model high poly in Z Brush- create low poly version in Maya by retopologising- UV map the low poly model- bring low poly into ZBrush and create the cracks and smudges- bake the high to low poly in X Normal or Substance painter.
High Poly Model
This was originally done by Even (the task of modelling, UVing and retopology assigned to her). The role was then taken on by Jack and myself.
The below is the original mesh we were given. Jack took the object and created a smoother model, we found areas like the legs had the mesh inverted and corrupted as the original retopology attempt was the high poly decimated to the extreme.
Retopology of High to Low
Jack and myself then worked on the topology together. Our original plan was to create both an ‘easy’ and a ‘hard’ rig set up. The easy being the rig only in the neck and tail, as these are the only parts really moving. Our hard rig would be the entire quadruped rig (Robert’s task).
Jack tried using the Z-Remesher in Z Brush to get perfect topology, however, this didn’t work out- giving n-gons and a lot of uneven areas. I tried using the normal maps from unwrapping it, however, it was creating odd artefacts, especially around the areas were the spikes were. A compromise we had was to create the spikes on a separate mesh instead.
Z-Remesher did not work out (above).
We decided to use quad draw to achieve the topology need, based on references we found online for dogs etc. We wanted the topology to be able to work with both the ‘easy’ and ‘hard’ rig setups.
Detailing in Zbrush
Using Jude’s advice I was able to plan out the texturing of the dinosaur, compiling a list of things this should include; smudges, scratches and finger prints.
I created the finger prints through creating my own alphas on ZBrush. I used the below video as a guide when I was unable to find any free ones available (which was surprising).
Creating alphas in Zbrush. (YouTube, 2017).
Baking the high to the low poly
I experimented with two different methods for baking here. Through the use of XNormal and then Substance Painter.
Firstly, I tried X-Normal. Cryengine.com had excellent documentation for creating perfect bakes, having tested basic methods before, I wanted to look into how to create this more accurately.
The article above suggested taking into account the following things;
Adjust the ray distance and default mesh scale= the scale between all 3D packages is different, to make sure xNormal has a good enough result and to make sure the rays hit a big enough mesh we should set the default mesh scale in xNormal to 16. This way we make sure the mesh is big enough to catch all the rays.
We should also set the ray distance to a higher value then the default one. The default value in xNormal is 0.5 which is too low and a lot of rays miss the target and double projections occur. A good value to start out with is to set our ray distance to 50 and tweak it from there.
Setting the correct bucket size and antialising settings=
The next setting we want to change is our bucket size. Normally we used to have the smallest bucket size (16) because the general impression was that it would be more detailed because it does 16 pixels per CPU core but after doing some research we found out that the highest (512) is faster. So if you use 512 and have a quad core with 8 threads, you will see 8 render blocks trying to render 512 pixels each in one go. What we don’t want set higher is our AA setting. 1x AA is enough and the difference to a 4x AA is minimal.
The same image has been rendered once with an AA setting of 1x the other of 4x. The 4x AA took 43 minutes to render! The 1x AA took only roughly 3 minutes. The difference is minimal and doesn’t justify the time. Plus also once our map gets reduced in size, like from a 2048 map to a 1024 Photoshop applies AA to image as it gets scaled down
I found I wasn’t getting quite the result with my mesh, the below padded look seemed to keep appearing in my normal map. I asked John Hannon (resident wiz kid) and he was able to explain what I had to to.
The mattress monster.
John explained I had to smooth my normals. I could this by going to mesh display- unlock normals. I then had to smooth the edges of the character and then harden the outer edges of the uv shell.
This worked and I was able to create a bake on the character.
I then added the character’s colouring and increasing the sub surface scattering amount to give more of the sculpted look.
You can see here I started to work on the blend shapes for Jack to created the facial rig, I’ll talk about these in a separate blog post.