Hello everyone,
While watching The lifecycle of SARS-CoV-2 by Phospho (Jeroen Claus) , I was deeply impressed by how elegant and accurate Houdini can be for creating biomolecular and cell biology content. This inspired me to start learning Houdini.
I learned the workflow of using VDB + POPnet from the YouTube creator golgi graphics to create the cell membrane fusion process. So, I tried to create my own cell exocytosis and endocytosis simulations.
My exocytosis setup went very smoothly. However, I ran into difficulties with endocytosis.
During the vesicle formation (invagination) process, the particles scattered on the surface always lag behind. My initial diagnosis is that the reference geometry (the vesicle) is falling too fast. When using xyzdist to map their positions, the particles cannot keep up, preventing them from forming a proper sphere.
I have tried the following adjustments:
Slowed down the falling speed of the sphere.
Increased the internal collision parameters of POP grains.
Although this barely allows the vesicle to form a sphere and pinch off, the particle movement becomes extremely violent (erratic/jittery). I also tried asking AI for help, but it didn't solve the problem.
I thought of a workaround: playing the exocytosis process backwards to simulate endocytosis. But this raises a few questions for me:
Why is the cell membrane movement in Phospho's work so smooth? Is it because our production approaches or underlying logic are completely different?
When converting VDB to Polygon, the topology changes drastically. Dear seniors, how do you solve the stability issue of surface scattered points (Points) under such severe topological changes?
Any advice or guidance would be greatly appreciated. Thank you very much!
Endo/Exocytosis: VDB particle instability
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- Bioredender
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- w_maro
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- Bioredender
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w_maroYour text to link here... [www.youtube.com]This is the link to The Lifecycle of SARS-CoV-2. Frame 327-331 can be regarded as endocytosis, and frame 331-335 can be regarded as exocytosis. The green part is the phospholipid bilayer, and the orange and yellow parts are proteins embedded in the surface of the phospholipid bilayer. In En.mkv, in this scene, I used boxes to simplify the phospholipid molecular layer. As you can see, because I increased the internal collision parameters, the particles collide violently, and it is not as smooth as in The Lifecycle of SARS-CoV-2. His approach seems not to use particle scattering to arrange the membrane and the proteins on it; it should be a different approach. During endocytosis and exocytosis, the topology of the geometry is actually changing all the time. If proteins are directly scattered on it, the proteins will flicker in and out and cannot be controlled.
Hello,
I have taken a look at your scene, but I cannot identify the problem (as I am not an expert on endo-/exocytosis).
Could you therefore provide a preview of your animation along with a few screenshots, and clearly mark where the issue lies?
Edited by Bioredender - yesterday 21:37:49
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