3D to 2D(UV) and back to 3D

[Rival Consoles]

Hi all,

I have been researching for this for days and so far haven't found a solution for this question. Maybe someone with more knowledge can point to the right direction. So, I have converted a 3D geo to a 2D version of it using the UV as reference through "@P = @UV". So far, so good. Now I need to perform some simple modeling procedures on the 2D geo like individual face extrusion, bevel etc and then bring the geo back to the original 3D version but with the modifications added.

Would someone know how to bring the modified 2D mesh to its 3D format but keeping the mods performed while it was in 2D?

Any suggestions would be appreciated.

Thanks. 

[kleer001]

Have you tried playing with a v@rest position attribute?

Set it for your base geo before you flatten it. Add another one, say v@rest2 to the 2D version. Set the position back to their initial rest, then move the points the difference between the rest and rest2. That will give you absolute transforms. But that won't be useful, say, on a sphere.

A better bet might be to duplicate your initial flat geo then point deform your modified geo based on the transformation of your initial flat back to the initial 3D. That's probably your best bet.

[Rival Consoles]

Hey kleer001, thank you for the suggestion. I'll try your approach and see how it goes.

[Masoud]

Hi Rival;

Please look for "ENTAGMA Knitting in 3d - Building a UV Deformer" in google.

It helps a lot.

[AntoineSfx]

On 1/10/2020 at 10:50 PM, Rival Consoles said:

Hi all,

I have been researching for this for days and so far haven't found a solution for this question. Maybe someone with more knowledge can point to the right direction. So, I have converted a 3D geo to a 2D version of it using the UV as reference through "@P = @UV". So far, so good. Now I need to perform some simple modeling procedures on the 2D geo like individual face extrusion, bevel etc and then bring the geo back to the original 3D version but with the modifications added.

Would someone know how to bring the modified 2D mesh to its 3D format but keeping the mods performed while it was in 2D?

Any suggestions would be appreciated.

Thanks. 

can't you just flatten the geometry before converting it back from "flat" (pseudo uv) to P, storing the elevation of the points which are no longer in the plane in an attribute, and move the points away from the surface along @N multiplied by that elevation attribute and some correction factor (because of changes in scale..) once you' re back in 3d space ?

[Rival Consoles]

@kleer001 Thank you so much for your input, using the point deform worked fine!

However, I noticed that bringing a model with UVs from other 3D packages to Houdini, when I convert the 3D model to 2D based on the UV, the 2D version is converted to a very small 2D model. lf I create the UV in Houdini, the 2D model size gets a little closer to the 3D size.

On the other hand, if I use any of the Houdini test geos with UVs the conversion from 3D to 2D is perfect and the sizes on both models (3D and 2D) match perfectly.

Is there a way to make sure that the UV island matches the 3D model size in Houdini. I.e.: If the 3D model with UV has 30cm in length how to make sure that its UV is also 30cm in length? Any help is greatly appreciated.

@Masoud thanks for the heads up. I watched that video and it is great.

@AntoineSfx I see your point, that could be another route I guess. Thanks for sharing your thoughts.

Edited October 13, 2021 by Rival Consoles