Hello, for my final major project at college I'm aiming to create something similar to the music video for wide open by the chemical brothers. I'm at post production stage now and I've finished all my motion capture stuff and I've started working on how to put it onto a model. I can't see anything wrong with the skeleton so I'm at a loss as to why the model is deforming so much. I also don't have a ton of experience in houdini, so any tips or suggestions would be really appreciated. I've linked the hip file for anyone to take a look at.
Thanks in advance!

https://drive.google.com/file/d/1NrJeXeSNx6eXGI-qKU3PlngjjDUI_XBT/view?usp=sharing [drive.google.com]

Hello there,

This appears to be a weighting issue. One that arises from the Bone Capture Lines SOP not playing very nicely with how Houdini imports FBX characters - i.e. cregions in nulls as opposed to bones

If you turn on the display flag on the Bone Capture Lines SOP you can see what's being brought in for the biharmonic capture to work with. If the ‘Use Bone Link’ parm is switched on then you should see a mess of ‘null’ shapes being brought in… With ‘Use Bone Link’ switched off, you should see a smaller numbers of isolated points floating around (make sure point display is on to see this), which comes from the target cregion being of near-zero length. The problem is that neither of these options offer very nice capturing with the biharmonic method.

It's a problem that I'll surely hit at some point, so I knocked up a quick hda that works around the problem and rebuilds the capture lines ready for the solid embed. You can dig around in there to see what's going on

Drop it down between the bone capture lines and the solid embed node and it should give you better initial results… Remember to re-stash!

Hope that helps,
Henry

I knew something was bugging me

I repaired the hda to allow for multiple children and also fixed the ‘resmaple by segment length’ to never produce fewer than 2 points per bone…

Here's the update!

On the “sknning_poly_bonecapturebiharmonic1_lines1” SOP, turn OFF:
Exclude Short Bones
Use Bone Link

and it should work.

Henry is right that because the fbx uses cregions inside nulls instead of Bones, this solution isn't the greatest.

Oh the capturing definitely works thataway, it's just a shame to lose so much of what makes the biharmonic method rad when using a single point at the centroid of the bone… ‘Cause by-golly-gosh it’s good when you give it enough to work with

In the image, the left one being with the single point from the cregion, the one on the right with the rebuilt capture lines.

friedasparagus
I knew something was bugging me

I repaired the hda to allow for multiple children and also fixed the ‘resmaple by segment length’ to never produce fewer than 2 points per bone…

Here's the update!

Hi!

I added your repair capture lines HDA as you showed and the lines are rebuilt correctly. But for some reason nothing is captured, all the points get a boneCapture w of -1. Any tips?

Thanks!

Hi eyestorm,

Do you have a hip file you can share? Much easier to pin it down in context

Cheers!

friedasparagus
Hi eyestorm,

Do you have a hip file you can share? Much easier to pin it down in context

Cheers!

Thanks for the reply! Here it is!

I *think* that the something is struggling with processing overlapping points in the capture lines that refer to different capture regions. Haven't been able to properly dig in, but placing a Fuse SOP in between the capture lines and the second input on the Solid Embed seems to get things working

friedasparagus
I *think* that the something is struggling with processing overlapping points in the capture lines that refer to different capture regions. Haven't been able to properly dig in, but placing a Fuse SOP in between the capture lines and the second input on the Solid Embed seems to get things working

Brilliant, that works perfectly! Thank so much for such a quick reply, your asset is a huge help!