Month: June 2022

This week I finished a spaceship water sim to test mid scene simulations. What I want to make is a spaceship coming out of ocean and interacting with the ocean water. The water sim must have enough details to represent the scale of the whole scene. What’s more, whitewater is covered in this sim to add more details on it.

To add more details on the sim. I create a custom noise field on the surface of the sim. When the spaceship coming out of the water, the noise field will affect the surface particles. Since the velocity data can be inherited by whitewater, it can also affected by the noise.

The fluid sim took me a lot of time to finish. The most difficult part is to mesh the fluid data and post-process it. I need to keep most of the details on the mesh and clean the edge and bottom of the mesh so that it can be successfully merged with the ocean source. It takes me days to simulate and fix the mesh.

Theecond part of the sim is to add whitewater(foam and bubble). I adjust the whitewater source and the sim several times to find a proper whitewater shape. After that I add just several parameters to add details on it.

A test render:

Ocean render test:

I output the render sequences and composite the background in nuke. Here is the result:

This week I focused on destruction buildings and smoke sim.

I gathered a procedual building HDA writen by some Houdini artist, which is quite handy for generating destruction buildings. By using this tool, I quickly built up a building that I want.

The next step is to fracture the building and turn it into a destruction ready building. I used RBD fracture and voronoi fracture to break all parts of the building and then cached the file to the disk. It took quite a long time to finish since the building has both interior and outside walls.

After that I added constraints to each part of the building so that it can be connected together when the sim started. All the constraints are glue constraints, which can be destoried after the collision object hit the building. I set about 20 constraints to connect the piece and exported them to the disk. Each constraint has be colored by using dofferent colors.

After the building has been set up, I started to test the collision. I find a suitable spaceship model on website and transfered it to VDB for collision. I used some nodes to limit the speed of fractures. After several times of tweaking, I finally got the result that I want.

After that I added debris on the fractured piece. I used velocity and volume as masks to prevent small pieces and low speed piece from emiting partcles. After that I used a pop sim to emit secondary particles from the original particles so that the volume source can get enough particles to form a trail, and then be generated into volume.

I generated flame, density, temperature and velocity source to simulate the smoke and fire. Several micro-solver have been applied to break the shapes of the smoke. The simulation still has some problem since I am not quite familiar with high speed volume sim. Some part of the smoke disconnected because of the high velocity and low substeps. I realized that I need to do more research on this kind of simulation to make the result looks better.

I tried to render out this sequence by using redshift. Unfortunately, my computer is not good enough to run the render in this scene because the cache is too big to be imported into render engine. When I click the render bottom, the screen just freezed. Therefore, I have to export a playblast to demonstrate the result.

This week I finished the eye rig for the monster and build the scene for our final shot in maya.

I started to rig the eye after Ziyin finished the modeling of it. The set of eye rig is not conplicated, which has eyelid controls, IK&FK eye controls and global controls. I added an offset group beyond the eyelid skeleton so that it can control the offset of eyelid when eye direction changed. I also added several blendshapes to correct the wrong deformations in this rig. Since the time is limited, I only added about ten blendshapes. The eye rig can be more flexible and realistic if I add more blendshapes on it.

A test for the eye rig:

I also rigged the pupil so that it can be zoom in or out:

After finished the rig, I started to build a simple scene for the final shot.

I build a simple background (cave) by using several noise nodes in Houdini. After that I import it into maya and use quixel bridge assets to build the foreground and midscene. After that I import all the rigs with textures inside this scene to do some layout and lighting. I want the monster eye hiding inside the darkness and character’s flashlight shooting towards it. The atmosphere must have some fog/smoke so that it can show the direction and shape of the light (Tyndall effect)

Here is a rendering test for this shot:

This week I finished character rigs for project01.

Since the time is quite limited, I choose to use ADV rig plugin as the tool to rig these characters. The setting of the rig is quite simple, I just need to make sure that the rig has a good skin weight and can be exported to game engines.

The painting of skin weight took me some time to finish. Our character has too many props on his body so that some of the skin weights are hard to deal with, especially the armpit and neck areas. I finally solved problems and finished the body rig.

Here is a walking test in ADV. Only a little bit of mesh crossing problem can be seen in the test, which is just fine:

Another character is the main character’s partner. Both of these characters wore same clothes. Therefore, I asked Zhenzhong to just replace the second character’s head so that I can easily copy the skin weight from the main character to the second one.

It took me 2-3 days to finish these characters’ rig. The next part is to finish the monster’s eye rig. What’s more, I will export the environment to maya this week so that we can start to make our animations and cameras.