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harper
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Joined: 19 Jul 2007
Posts: 283
Location: Hamburg, Germany
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 Posted: Fri Apr 09, 2010 11:04 am Post subject: reducing polys |
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| Its just a thought: Are there any (theoretically) methods of reducing the complexity of models, like LOD on terrains? |
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chronozphere
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Joined: 20 Jun 2006
Posts: 1010
Location: Netherlands
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| Posted: Fri Apr 09, 2010 11:14 am Post subject: |
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There are lots of ways... I'm afraid that DeleD doesn't support any of them yet. This is still something you need to do by hand.
I wish I had time to implement such a tool. |
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Jeroen
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Joined: 07 Aug 2004
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Location: The Netherlands
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| Posted: Fri Apr 09, 2010 11:35 am Post subject: |
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Well, there's the Optimize tool, but that's not quite similar to things like LOD. Implementing such tool, from a developers point of view, would be pretty interesting.  Not sure if we really need it in a low-poly editor like DeleD though. This is the first time I see this request.
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fik
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Joined: 11 Oct 2006
Posts: 303
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| Posted: Fri Apr 09, 2010 11:43 am Post subject: |
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| Automatic poly reduction is a great problem to get right, even high end moddling progarms like 3ds max etc. still have horrid results. Its always best to do by hand or make a seperate lowpoly model using highpoly as a template. |
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harper
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Location: Hamburg, Germany
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| Posted: Fri Apr 09, 2010 4:42 pm Post subject: |
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| It was only a thought. But when i hear that for many engines very-low-poly models for collision-detecting are needed, then such a function makes sense, or? |
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Starnick
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Joined: 28 Jul 2007
Posts: 611
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| Posted: Sun Apr 11, 2010 4:30 am Post subject: |
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| harper wrote: |
| It was only a thought. But when i hear that for many engines very-low-poly models for collision-detecting are needed, then such a function makes sense, or? |
Low-poly versions of a mesh for LOD and collision meshes are really two different areas. There are tools out there, as well as techniques to automatically create LOD models and collapse the mesh down to a simpler shape...but yeah usually the manual method creates better meshes (albeit slower and tedious no doubt).
Simple shapes for collision, it's not so much collapsing the mesh, as it is either using simple primitives (bounding volumes - Axis aligned boxes, oriented boxes, spheres, capsules) or more advanced methods where its not exactly a primitive, but a simple shape that fits the mesh entirely...e.g from an Unreal tech collision tutorial:
http://udn.epicgames.com/Two/rsrc/Two/CollisionTutorial/kdop_sizes.jpg
http://udn.epicgames.com/Two/rsrc/Two/CollisionTutorial/show_collision.jpg
The last one the hanging piece of meat is surrounded by something that isn't exactly a primitive, like a box or sphere. Some cases this is a generated volume.
This can be done manually too, e.g. in DeleD I create boxes and spheres and they get read as an oriented bounding box or a bounding sphere. So rather than just a single bounding volume that encapsulates the entire mesh, there's also a list of smaller bounding volumes that approximate it a lot better. When the model gets imported into my engine, I extract those tagged primitives and have them listed with the model when I do collision tests. If you've ever looked at how collision handling is done in Multiverse, its more or less the same sort of system. As well as lots of other engines/platforms out there. |
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stumcd
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Joined: 02 Jul 2006
Posts: 37
Location: Edinburgh - Scotland
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| Posted: Sun Apr 11, 2010 1:14 pm Post subject: |
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| Probably the best mesh manipulation program is MeshLab. It's a superb tool with a lot of powerful features. Very technical, but if you just want to reduce the poly count then "Filters->Remesh->Quadradic Edge Collapse" (with texture if it has a texture) is the simplest. |
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Starnick
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Joined: 28 Jul 2007
Posts: 611
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| Posted: Sun Apr 11, 2010 5:09 pm Post subject: |
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| stumcd wrote: |
| Probably the best mesh manipulation program is MeshLab. It's a superb tool with a lot of powerful features. Very technical, but if you just want to reduce the poly count then "Filters->Remesh->Quadradic Edge Collapse" (with texture if it has a texture) is the simplest. |
Good find, this was the tool I was thinking of when writing my last post but I couldn't remember the name of it. I used it a long a time ago and it was pretty good. It also has functionality to clean up the mesh if I remember too (e.g. eliminate stray vertices, etc). |
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Jeroen
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| Posted: Mon Apr 12, 2010 6:37 am Post subject: |
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Are there any tools in MeshLab that are relatively easy to implement in DeleD?
Eleminate stray vertices sounds cool and I think something similar is already part of the Optimize tool. If all we have to do is make the various parts of the Optimize tool available separately (delete redundant vertices, merge polygons etc), then that would be very much doable.
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AWM Mars
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Joined: 06 Jan 2010
Posts: 1195
Location: Wilts England
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| Posted: Mon Apr 12, 2010 12:10 pm Post subject: |
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| Jeroen wrote: |
Are there any tools in MeshLab that are relatively easy to implement in DeleD?
Eleminate stray vertices sounds cool and I think something similar is already part of the Optimize tool. If all we have to do is make the various parts of the Optimize tool available separately (delete redundant vertices, merge polygons etc), then that would be very much doable. |
That sounds like a worth while project. I have found for the most part, Optimise worth using at least once on a model. On a few occassions it actually increases the vertices and poly count, this is usually after a CSG function. I can only imagine the complexities of how a programme would determine what you want and what you don't want lol. Overall optimise does a good job.
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chronozphere
DeleD PRO user
Joined: 20 Jun 2006
Posts: 1010
Location: Netherlands
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| Posted: Mon Apr 12, 2010 2:30 pm Post subject: |
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| Jeroen wrote: |
Are there any tools in MeshLab that are relatively easy to implement in DeleD?
Eleminate stray vertices sounds cool and I think something similar is already part of the Optimize tool. If all we have to do is make the various parts of the Optimize tool available separately (delete redundant vertices, merge polygons etc), then that would be very much doable. |
Sounds like a good plan.
Would also be nice if we could do some really strict mesh checks for:
- non-planar polygons
- concave polygons
- redundant polygons/edges inside the geometry.
etc..
Some kind of mesh diagnostic tool. Very handy if you want to use it in a game, because some loaders/engines require "strictly nice" geometry.  |
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pythe
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Joined: 04 Apr 2009
Posts: 2
Location: Estonia
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| Posted: Sun May 02, 2010 12:18 pm Post subject: |
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What about deleting all outer or inner faces?
For example: if you create a pyramid of two-sided rectangles(merged together) then you don't want those inner faces anymore because you are "never able" to see those faces.
or: two cubes are on each other, the top cube is smaller. It would be cool if it would be possible to delete those faces between those two cubes.
Such tool would help also to reduce the size of light maps. |
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