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雪紅杉林

Week1

VAT vs USD Pipeline Test

Jan 9

VAT: 

First, I used Yichen’s Fern to test the VAT pipeline. However, due to the high polygon count (205,975 polygons) and the long animation duration (240 frames), the texture rendering process tends to fail.




I looked into the Houdini community and found an artist who proposed a formula to determine the most suitable number of primitives and frames for rendering.

VAT point count limits per texture size? Frame range limit?
The result is: I have been multiplying the frame count by the point count and dividing by the texture size (frame_count*point_count)/texture_sizeand it seems if that number is below 9000, it completes successfully. But I'm grasping at straws here through trial and error.
Here is the link: https://www.sidefx.com/forum/topic/85129/?page=1#post-368221



 

image.png

So, I decided to reduce the polygon count and also tried to export the animation separately, exporting 1-100 frames and then 101-240 frames. I met the problem, and the animation looks glitchy and I found a very useful VAT Debug.
Link: https://www.sidefx.com/forum/topic/81422/#post-350761



 

This is because of a change in the build setting. 

Screenshot 2026-01-11 222301.png

Still need to figure out why the animation is flickering.

Screenshot 2026-01-12 121640.png

USD:

For the USD pipeline, I experimented with creating USD instancing in Houdini and found that using Packed Primitives significantly reduces memory usage. Here I tested 15 ferns.

Screenshot 2026-01-11 224940.png
Screenshot 2026-01-11 225050.png

Size Comparison

Before

After

Visual Comparison

Next Week:

  1. Try USD instancing in Houdini

  2. Try USD instancing in UNREAL

  3. Try VAT instancing in both in Houdini and Unreal

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