WOOSEUNG CHO

I have conducted a test, and most of my questions have been resolved. It is unfortunate that I cannot share the scene file, as it is a company asset.
The purpose of this test was to determine which method yields the highest quality results.

1. Hair Generate (OBJ) with "Perform Hair Generation and Editing at Rest" turned OFF
This method produced the best quality. The issue where the hair curves seemed to disappear was not actually a deletion; rather, the hair would suddenly pop into an empty space for a single frame and then fly off elsewhere in the next, making it look like it was vanishing. Since the curves used as guides were not smooth, this was an understandable issue. Based on the procedural setup within the Hair Generate node, it maintains a consistent clump shape from the guide curves every frame.

2. Guide Deform (SOP)
First, I tested using weights generated by Hair Generate versus using Barycentric weights.
When using the weights from Hair Generate, the issue was barely noticeable during subtle movements, but under heavy wind conditions, the hair failed to follow the guides properly. I suspect this is because the weights are determined at the moment of hair generation and do not account for subsequent changes. There also seems to be an inherent limitation to the weight-based movement approach itself.
Secondly, while Barycentric weights kept the hair more closely attached to the guides, they caused a significant loss of the clump details that were already established.

Ultimately, as you suggested, the first method appears to offer the best quality. If using Houdini as a grooming tool, there seems to be no real need to rely on weight-based deformation. Furthermore, if weight-based deformation must be used, it seems essential to have a large number of guides covering the entire hair curve area.

One remaining question is how to clean up the data flow between the groom and simulation:

1. Export the Guide Groom as a .bgeo and load it alongside the Hair Generate node.
2. Build one massive SOP network that encompasses everything from guides and simulation to hair generation.
3. Or is there another preferred method?

Since I am now using a tool where everything connects organically from start to finish, it feels a bit psychologically unfamiliar compared to my previous segmented workflow. :S

Oh...! Thanks to you, I think I know what the problem is with my scene. Thanks for the tip! I'll give it a try as you said

Thank you for your response! evanrudefx

Overall, my thoughts align with yours. If a guide groom is already available, I believe using it in conjunction with a hair generator is the best way to achieve diverse variations.

However, I’ve encountered some issues that I suspect are stemming from the use of the guide groom/hair generator setup. As you mentioned, when there are too few guides, the hair tends to flicker (appear and disappear), or the guide simulation remains smooth while the hair itself bounces. In these cases, I’ve been manually selecting and removing individual hairs—luckily, the situation in this project allowed for that—but it feels like a completely undesirable approach within a professional pipeline.

Secondly, because the pipeline wasn't very sophisticated, it was extremely difficult to track the root cause when problems arose with the guide groom or hair generator. Since I’m a Houdini novice, this feels like a particularly big challenge.

As you said, if you were in my shoes, you would have likely created the guides from the groom, right?

I have a few additional questions:

Is it correct that the issues mentioned above are related to the guide groom / hair generator as I suspect?

I’d like to clarify the terminology. Can I assume the 'guide' you’re referring to is the guide groom node, and the 'groom' refers to the curves created by the hair generator?

Additionally, could you tell me where I can check the generation weights you mentioned?