Timeline for maximal convex patching in Computer graphics
Current License: CC BY-SA 3.0
20 events
| when toggle format | what | by | license | comment | |
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| Apr 29, 2016 at 13:09 | vote | accept | Sushovan Mandal | ||
| Apr 4, 2016 at 12:39 | comment | added | trichoplax is on Codidact now | Your description of how the torus should be divided is perfectly clear, but I can't see a way of translating that into a rigorous requirement that would apply to other types of surface. The strips are distinct from each other due to concave edges, but they all seem to be connected to the large outer convex patch, and therefore part of it. I think the main question here is how to unambiguously define what a maximal convex patch is. | |
| Apr 4, 2016 at 7:57 | comment | added | Sushovan Mandal | @trichoplax strictly convex is what I am looking for. In the example of the Torus, I require an algorithm that makes the outer half of the torus a single convex patch, with the visible (the inner surface of the other side of the torus will be visible to the viewer) triangles on the inner half (around the hole) , that forms a concave lateral arc to the viewer, it should show convex strips perpendicular to the concave arc. I hope I was able to communicate the idea effectively. | |
| Apr 3, 2016 at 11:38 | comment | added | trichoplax is on Codidact now | It may help to consider a torus. Do you require an algorithm that makes the outer half of the torus a single convex patch, with the triangles on the inner half (around the hole) not counted as being in any convex patch? Or do you require an algorithm that makes the whole surface of the torus a single convex patch, since even on those parts of the surface that are concave in one direction, they are still convex in the perpendicular direction? | |
| Apr 3, 2016 at 11:15 | comment | added | trichoplax is on Codidact now | I meant that the curved surface of the cylinder is itself flat in the direction parallel to its central axis. Depending on whether you move to the next triangle around the cylinder or along the cylinder, it will appear to be either strictly convex (moving around), or flat (moving along). Do you require the surface to be strictly convex in every direction, or only one direction? | |
| Apr 3, 2016 at 8:45 | history | edited | Sushovan Mandal | CC BY-SA 3.0 |
provide more comprehensive description
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| Apr 3, 2016 at 8:43 | comment | added | Sushovan Mandal | @trichoplax thanks for the suggestion! yes, a convex surface which is not a subset of a larger convex surface, is what is meant. And yes, it needs to be strictly convex. For a cylinder, there would be one convex patch in the whole figure which is maximal, and this patch would not include the axial flat surfaces. | |
| Apr 2, 2016 at 7:59 | comment | added | trichoplax is on Codidact now | It would be helpful to know what the purpose is, to give a better idea of exactly what is required. For example, does a convex patch need to be strictly convex (never flat), or does it count as convex provided it is nowhere concave? A cylinder is nowhere concave. It is convex everywhere, but it is not strictly convex in every direction (it is flat in the axial direction). Do you want the surface of a cylinder to count as one convex patch? | |
| Apr 2, 2016 at 7:51 | comment | added | trichoplax is on Codidact now | The comments on your answer suggest some confusion over what is meant by "maximal". I believe you are using "maximal" to mean a convex surface which is not a subset of a larger convex surface, rather than to mean the largest convex surface that exists in the triangle mesh. This is covered in your question but due to the confusion it might be worth editing to clarify. | |
| Mar 30, 2016 at 6:49 | vote | accept | Sushovan Mandal | ||
| Apr 4, 2016 at 13:42 | |||||
| Mar 30, 2016 at 6:44 | history | edited | Sushovan Mandal | CC BY-SA 3.0 |
better
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| Mar 20, 2016 at 4:04 | history | edited | Sushovan Mandal | CC BY-SA 3.0 |
provide more comprehensive description
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| Mar 20, 2016 at 4:02 | comment | added | Sushovan Mandal | @nathanreed Below I have posted an answer that should work, can you improve upon it, or can you provide a better solution? | |
| Mar 20, 2016 at 4:01 | comment | added | Sushovan Mandal | @nathanreed opengl will be used to render the objects, processing algorithms are to be done in C++. I have to apply different colors to the different convex patches on the object to signify the selection. Say I have a sphere then the whole sphere is one maximal convex patch. Any portion of the sphere surface will be a convex patch, by maximal I mean the maximum continuous convex patch that can be found. Well in the rendering, depending on the viewing angles, the maximal convex patches visible to the viewer will have to colored. | |
| Mar 20, 2016 at 3:54 | answer | added | Sushovan Mandal | timeline score: 1 | |
| Mar 20, 2016 at 3:53 | history | edited | Sushovan Mandal | CC BY-SA 3.0 |
better explain the question
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| Mar 19, 2016 at 2:22 | comment | added | Nathan Reed | OpenGL doesn't seem like it would help here; it's a computational geometry problem, not rendering. Can you edit the question and define your terms better? What do you mean by a "maximum continual convex patch" exactly? | |
| Mar 19, 2016 at 2:20 | history | edited | Nathan Reed |
edit tags
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| Mar 18, 2016 at 9:17 | review | First posts | |||
| Mar 22, 2016 at 13:42 | |||||
| Mar 18, 2016 at 9:08 | history | asked | Sushovan Mandal | CC BY-SA 3.0 |