This week we still focusing on rendering and compositing.
What I did this week is almost the same as the one that I did last week. I finished the other part of the simulation and rendered other animations.
When I did the simulation for the dream sequence, I realized that the character’s eyebrows still have some problems. I used wrap deformer to rig the character’s eyebrow. It works well when the character is in initial size. However, it becomes a little bit weird when I scaled the character. Frankly, that is a stupid mistake. Since there is no time left to adjust the rig, I told ziyin to scale the character back to the initial size to prevent the BUG happening. Although the wrap deformer can make the rigging process faster, it still has limitations. Next time I will turn to use skeleton to rig the eyebrow, which can be much safer.
What the simulation that zhengzhong wants is the water pouring out of the pot and collide with the water inside the tea cup. He wants the waterline keeps rising, which can show how dangerous the character’s circumstances is. Therefore, I used flip solver in Houdini to simulate that scene. What I did is to create two flip sources: one is for the ground water sim, the other is for the pouring water sim. Both of these sources collide with each other.
My computer is not good enough for high-res water simulation, so the detail is not quite satisfying. What’s more, there is one problem: The camera goes through the water in part of that sequence. Ziyin said that the camera should not be changed. Therefore, I have to use some tricks to deal with this problem.
What I did is to simulate the water twice: one is the water coming from the pot, the other one is the whole simulation with water collision and interaction. Then I used the switch node to switch between these two caches.
When the camera moves, I switch to the pot water cache(without collision) to prevent the water from crossing the camera. After that I cached out the whole sim to another alembic file, which is the final version.
The final version of the sim:
Reflection: After using flip solver for several times, I realize that flip solver is not quite suitable for small space simulation, for the collision of particles often has small issues. If I want a better result, the substeps must be added, which will make the sim much slower. I will do some research on that, trying to figure out a better way to prevent these small problems. Also, I will do some research on how to improve the details of water sim.