Month: October 2022

VFX

This week I did the third simulation, which is an explosion & RBD simulation.

I want the hands of creatures suddenly hit ceiling and smash the ceiling tile on the ground. Therefore I firstly fractured the ceiling tile and ceiling frame. After that I used hard constraint + soft constraint to mimic the deformation of tile. The hard constraint will broke based on how big the impact is, and then generate into soft constraint to keep the pieces together.

After the make of RBD simulation I then made debris particles and debris pieces, and finally simulate a simple pyro smoke to mimic dust. To make the smoke cache file smaller, I used VDB camera clip to remove VDB imformation outside of camera.

The most difficult part of this shot is the high-speed simulation, which requires more substeps of sim, which took many time to finish.

Compositing

After I finished VFX shots I started compositing some of rendered shots. I build up a compositing templete in Nuke so that I don’t need to redo the same thing again and again. I used z depth channel and motionvector channel to add depth of field and motionblur on shots. I also exported each light layer individually so that I can change each light information in Nuke.

This week I started to make VFX shots.

There are several shots that requires VFX:

• two blood shots
• one explosion & RBD shot

The first VFX shot is a blood liquid shot. I want the blood to slide on the surface of the printer, and the blood should be quite thin. Therefore, I generated a thin geometry and transfer it to points as the fluid source. I also turn on stick on collision tab to mimic sliding effect. I added some thin blood strings to make the whole liquid more detailed.

The second one is also a blood liquid shot. The blood needs to flow on the carpet and wet papers. I firstly used flip fluid to do the simulation. The flow looks good, but the generated liquid is too thick. The reason why the liquid is too thick is because the resolution of volume in simulation is not high enough. However, high resolution of volume will bring more simulation time and hardware pressure, which can be another problem. Therefore, I turned to use particles to mimic fluid simulation. I added particle fluid node into pop simulation so that forces between particles will be created. To make the cache file smaller, I used toNDC function to group the particles outside of camera and delete them. By adding masked smooth and meshing techniques, the final result looks fine. After that I use sop solver and attribute transfer to make the wet maps on carpet and paper, and later generate them as material masks. By using the wet map, carpet and paper can change materials when the blood flow over them. They will become darker and redish.

Next week I will finish the last VFX shot.

This week I finished all the animations in this short film. It is my first time doing so many animations in a single project, which can be quite struggling. Any way, I finished it.

I also spend some time to look back all the shots, making sure that there will be no bugs in them. After fixing some animation problems, adding more details and changing some lighting in the scene. I started rendering.

Since some of scenes can only be rendered after I finished VFX part, I put these shots into the last part of my rendering schedule. This time I used redshift and arnold to render these scenes. Redshift rendering is extremly fast and can preserve high rendering quality, which can be the best choice to me. Arnold is only used to render one shot (the eye close-up shot), for it’s SSS material quality is much better than Redshift.

Next week I will start to do VFX parts, which will cover some liquid shots and an explosion & RBD shot.

Last two weeks I finished about half of all animations. I finished some of the other animations this week. Next week I will try to finish the last part of it and spend some time to get back to the first one and repolish some of these shots.

During this week I met some small problems. I tried to make the shaking effect of the printing machine and these creepy hands. I want the print machine and hands to shake really fast and weird. At first I tried to animate these by hands. However, the result is not quite satisfying. Also, I need to animate almost every frame since the shaking is really fast, which can be quite boring and will cost huge time. Therefore, I tried to write expressions for these controlers so that the shaking effect can be controled by math. I used some noise and random functions to control the way of shaking. Though The result is not perfect, it is good enough for these shots.

I also get back to the rig of printing machine and added a shaking controler for it. Just like what I did for the foot controler before, this controler can rotate the base of print machine in 360 degrees. By adding this controler, I just need to write one expression to control the shaking of machine, which can save energe and time.

Just like last week I’m still focusing on making animations. As I have already made several animations, the speed of animating becomes faster this time.

I also added several shots into the storyboard this week since I found that the translation between some shots are not quite natural. I also added more reaction shots to show the facial expressions of the character. This change made the rhythm looks better, but also increased a huge amount of works.

There is nothing fancy this week. I just keep making facial animations and body animations. Animation is a huge task, which is also something that takes time and patience. I am not an expert on animating, but I will try my best to make it as good as possible.