[HN Gopher] Implicit UVs: Real-time semi-global parameterization...
___________________________________________________________________
Implicit UVs: Real-time semi-global parameterization of implicit
surfaces [pdf]
Author : ibobev
Score : 43 points
Date : 2025-05-12 10:46 UTC (12 hours ago)
(HTM) web link (baptiste-genest.github.io)
(TXT) w3m dump (baptiste-genest.github.io)
| whizzter wrote:
| Interesting paper for someone fiddling with implicit surfaces,
| but it's gonna take a little while to digest it. Also there's no
| examples of resulting UV maps used in this (while on-model
| painting is simplified, afaik classically artists still preferred
| to get clearly delineated maps to modify in regular painting
| software even if stuff like Substance painter seems to have
| shifted that).
|
| Implicit surface modelling tools are still evolving quickly, and
| one point that seems overlooked is how this would tie with
| authoring tools (since this is about a fairly raw numeric
| algorithm solution).
|
| Post-modelling it should hold up, but would the maps retain
| similarity (or enable transferability) if the implicit model
| structure changes?
|
| Imagine 2 disjoint spheres in space, the user drags them
| together, would this algorithm want to merge the UV mapping of
| them if they are smoothly joined? (no sharp creases).
| baptiste-genest wrote:
| Hi, I'm the first author of the article. Thank you very much
| for your interest in the method!
|
| For the 2 spheres, it's as you wish ! It depends on where you
| place the uv system in the CSG tree, if it is above a single
| sphere then it will remain on it, if it's above the union, the
| field should extent on both.
|
| The main interest of the method is the fact that the output
| remains implicit so one can easily plug it in a CSG pipeline.
| jplusequalt wrote:
| What a great paper. This paper is an example of why I find
| computer graphics to be the most interesting subset of computer
| science.
| baptiste-genest wrote:
| Hi, I'm the first author of the paper. Thank you so much for
| your comment, it means the world to me!
| kaoD wrote:
| Related question: I'm coding a demo (as in "demoscene") and want
| to displace a plane SDF (think e.g. a heightmap) for raymarching.
|
| This produces some visible discontinuities in the plane at larger
| slopes. My surface is still at f(x,y,z) = 0 but the rest of the
| field is completely messed up. From the little maths I know, that
| is no longer an SDF because among other issues, it no longer
| satisfies the Eikonal equation mentioned in the article.
|
| Is there any way to fix this or am I SOL?
| bhouston wrote:
| You need to take the minimum of the two SDF fields in the
| surrounding region (up to the global context if you need to) if
| you want it to maintain an SDF. The minimum of two SDFs is
| always a new SDF.
|
| My suspicion is that the new plane isn't an SDF anymore, that
| is why you are getting artifacts or your ray marcher has
| problems with large scope angles, or something.
| akomtu wrote:
| sdf(p + sin(p)*0.01)
| GistNoesis wrote:
| See "Deformations and distortions" paragraph in
| https://iquilezles.org/articles/distfunctions/ where it
| suggests playing with the ray-marching step size.
| Remnant44 wrote:
| Great timing on this paper. I actually just started tackling a
| problem that is essentially exactly what is under discussion here
| (creating a coherent UV set for implicit geometry), so I'm very
| looking forward to reading it in depth.
|
| At a first glace through, it seems to be written at a good blend
| between concept and implementation followthrough, something that
| notoriously is not always there for CG papers :) And it's also
| refreshing to read something that is not neuro-AI-generation of
| this or that for a change!
___________________________________________________________________
(page generated 2025-05-12 23:01 UTC)