AttibTransfer in UV space

[AaronAb]

How can I use UV space instead of world space to transfer attributes in Houdini?

 

 I'm trying to do this : http://www.zbrushcentral.com/showthread.php?132415-Energise%B4s-Sketchbook-%28mini-tut-pge-5-6-amp-17%29/page17 (scroll down to second set of images Odforce didn't like the direct link).

 

[Skybar]

I guess you could move the points to their position in UV, transfer or do what you want, and then move the points back to their original position.

[eetu]

You could just temporarily move the points to their uv-coordinates, do the attribtransfer, and move them back to the original coordinates. Discontinuous vertex uvs might need extra care.

 

edit: ha, Skybar beat me to it

ee_uv_attrib_xfer.hip

Edited June 26, 2014 by eetu

[Skybar]

You could just temporarily move the points to their uv-coordinates, do the attribtransfer, and move them back to the original coordinates. Discontinuous vertex uvs might need extra care.

 

edit: ha, Skybar beat me to it

Hehe but you had a hip

 

Extending yours to show my take on it:

dv_uv_attrib_xfer.hip

[pezetko]

Seems I'm late, but I have a little bit different combination of nodes.
(attrib wrangle instead of point sop and vertex split for uv seams (instead of facet))

 

pz_attrib_transfer_in_uv_space.hipnc

Edited June 26, 2014 by pezetko

[Skybar]

Oh wow, seems I have overlooked the Vertexsplit SOP - I actually needed exactly that today at work. Cheers pezetko

[AaronAb]

Holy crap! thanks a ton guys! gave me lots to look through here!

[AaronAb]

Alright I've investegated the .hip provided by Pezetko but run into a snag. I can't seem to get my quad mesh to go back to the original position of the tri mesh, I have attached a .hip of where I am at with this.

 

 Thanks again everyone for your help.

 

 

pz_attrib_transfer_in_uv_space2.hipnc

[Skybar]

I don't quite get what you were trying to do, most of it makes no sense. Instead take the first frame of your tri-mesh, bring that to Zbrush or something and make it into quads. Then bring the tri-mesh animation and single frame quad-mesh into houdini, and cloth capture/cloth deform the quad to the tri. 

 

edit: Well I guess you could cloth capture the quad when they're both in the UV position. You would probably have to single out the different elements though since they are pretty close to each other. I did a quick test and it works to 90%, would probably work if you spent a bit more time on it.

Edited June 29, 2014 by Skybar

[AaronAb]

Zbrush's zremesher isn't suitable for games work unless used very carefully and very specifically, such as remeshing un-simulated cloth panels from Marvelous Designer. I would also have to re do uvs if I use Zremesher on simulated geometry. The basic workflow is quite easily achievable in Maya with it's attribute transfer, as it offers more ways to transfer attributes out of the box than Houdini does. However in Houdini a much slicker workflow could be achieved with a digital asset allowing me to come to an optimized topology solution quicker.

 

 Here's a little example of what I am doing in Maya, but would rather do in Houdini.

 

 I've got much more complex pieces of cloth I have to get ready for runtime and a smoother workflow that would allow for more intuitive iteration was the reason I reached for Houdini instead of just staying in Maya.

[pezetko]

There was too many errors in your example so I rather rebuilded it to working solution, hope this is what are you going after.

 

pz_attrib_transfer_in_uv_space_example.hipnc

[AaronAb]

That is exactly it! Thank you so much for your help! Feel a littel bad seeing how much work that actually turned out to be. Thanks again.

[xukca]

There is some really good information here, amazing work guys! But how would you approach the following problem: uv-ing a  geo cache without UVs with non-constant point count (debris sim). I  timeshifted to the last frame, created the uvs... but then how should I transfer them to the animation? I have some ideas about procedurally deleting chunks from the timeshifted frame, so I can match its geo to the current frame animation  and apply a copy attribute SOP, but this seems to be very expensive to compute? :/ (and I dont know if it is going to work). Any workflow suggestions?

 

p.s. actually, it seems, its computing pretty fast, but there is still some kind of a discrepancy by point/prim/vertex count and the attribute copy sop is messing up the uvs... :/

Copy_uv_02.rar

Edited July 12, 2014 by xukca

[AaronAb]

Just wanted to add that there is now a new node in Houdini 14, Attribute Transfer by UV that performs the task perfectly. Pretty nice too see this added to Houdini.