Voxelizer
category: code [glöplog]
Hi all,
This may be something we have discussed again in the past, but as technology changes I think we can talk about it once again: I would like to make a fast voxeliser. What I mean by that is a process where you take a 3d model and convert it into a 3d volume so that all voxels within the model are 1 and the rest us 9. By fast I dont mean realtime (but would be cool to!), but, say, a few secs for 512^3.
You'd do this on the gpu, somehow. I imagine by rendering slice by slice (with backface culling off) into a 3d texture. Would there be something easier or faster. And what about a 3d volume where each voxel is the shortest distance to an empty voxel. How could that be generated without image postprocessing so to speak?
This may be something we have discussed again in the past, but as technology changes I think we can talk about it once again: I would like to make a fast voxeliser. What I mean by that is a process where you take a 3d model and convert it into a 3d volume so that all voxels within the model are 1 and the rest us 9. By fast I dont mean realtime (but would be cool to!), but, say, a few secs for 512^3.
You'd do this on the gpu, somehow. I imagine by rendering slice by slice (with backface culling off) into a 3d texture. Would there be something easier or faster. And what about a 3d volume where each voxel is the shortest distance to an empty voxel. How could that be generated without image postprocessing so to speak?
Might not be the thing you search at all, but Blender has a remesh modifier - that is able to "minecraftify" a model. HTH? O_o;
A kind of inverse marching cubes.
yes, in a way.
navis; this does what you describe http://www.cs.princeton.edu/~min/binvox/
http://maverick.inria.fr/Publications/2008/ED08a/solidvoxelizationAuthorVersion.pdf
some ideas here... good midnight read :-)
some ideas here... good midnight read :-)
Damn that thing is fast.
In "GPU Pro 3" theres also an article about it called "Practical Binary Surface and Solid Voxelization with Direct3D 11" by Michael Schwarz. He also has another article called "Fast parallel surface and solid voxelization on GPUs" on his homepage.
The models are not "filled", but only a solid voxel shell and could therefore be stored quite efficiently with e.g. sparse voxel octrees. It's not exactly what you asked for but might be interesting to take into consideration ...
The models are not "filled", but only a solid voxel shell and could therefore be stored quite efficiently with e.g. sparse voxel octrees. It's not exactly what you asked for but might be interesting to take into consideration ...
> The models are not "filled", but only a solid voxel shell
Like a chocolate easter bunny? ;)
Like a chocolate easter bunny? ;)
There's more on this topic by Schwarz iirc - you want the thing with the front face/back face rendering and XOR. It's pretty damn fast (realtime) and if you compact 32 binary voxels into one cell for one axis you can get away with a 512x512x16 texture :).
here's just an idea. for a simple uniform algorithm for random voxels. with collision detection, inside a mesh if you know you are inside it (a hollow surface) start with a box that is 0 length and scale each side of the box. when it hits an triangle-edge (of the mesh) stop, move each corner of the box slightly in a random way, dont decrease the volume but keep the length of the side. when volume doesnt change (with or without an epsilon value depending on the mesh structure) start on next box, but place it randomly inside the mesh like the first one, excluding the previous box volume. then one could schange the algorithm for box with equal side-lengths or not for a slightly different type of voxel-effect. use ray to trace against each triangle of the mesh or a better option. if this is too intensive hack together an invertible marching cubes like Adok mentioned.
+1 the depth peeling/XOR algorithm. Works like a charm and is pretty fast.
Render a model to 6 depth buffers from each axis / direction and with 3 look ups you get a position for a cube. Has a lot of flaws, but might work for some simple models.
can you elaborate more on the depth peeling xoring thing please?
Navis: I think Smash' presentation at GDC 2012 about generating SDFs from triangle meshes in uncovering static could be useful.
Dear friends,
Sorry for digging out this thread but it fits the topic I want to talk about.
The program our company sells internally stores the 3D model as a set of cuboids. As a new functionality, my boss wanted that I add import of DXF and IFC files. I worked on this for half a year and I am pleased with the result but my boss is not. Because we use cuboids in our program, I developed a mesh voxelizer. Basically it takes a look at the center of each voxel and determines whether the voxel should be set by scanning all the faces and checking whether the face intersects with the voxel. To achieve this, I rotate the face and the center point of the voxel so that they are in planes parallel to the XY plane, then I check the Z distance and, if it is within the limit, I check whether the center point of the voxel is inside the polygon determined by the face. It works very well but my boss is still unhappy simply because it does not look perfect - which is impossible to achieve with a voxelizer, voxel graphics will always look more coarse than the original mesh!
Now I wonder how I should explain that to my boss, as she keeps insisting that I should spend my sparetime conducting further research and finding a "better" mesh voxelizer.
Sorry for digging out this thread but it fits the topic I want to talk about.
The program our company sells internally stores the 3D model as a set of cuboids. As a new functionality, my boss wanted that I add import of DXF and IFC files. I worked on this for half a year and I am pleased with the result but my boss is not. Because we use cuboids in our program, I developed a mesh voxelizer. Basically it takes a look at the center of each voxel and determines whether the voxel should be set by scanning all the faces and checking whether the face intersects with the voxel. To achieve this, I rotate the face and the center point of the voxel so that they are in planes parallel to the XY plane, then I check the Z distance and, if it is within the limit, I check whether the center point of the voxel is inside the polygon determined by the face. It works very well but my boss is still unhappy simply because it does not look perfect - which is impossible to achieve with a voxelizer, voxel graphics will always look more coarse than the original mesh!
Now I wonder how I should explain that to my boss, as she keeps insisting that I should spend my sparetime conducting further research and finding a "better" mesh voxelizer.
BTW, the "mother" of all publications regarding mesh voxelization, which is most often cited, is this:
Huang et al. (1998): An Accurate Method for Voxelizing Polygon Meshes
Some other good papers I've found are:
Zlatanova et al. (2016): Towards 3D Raster GIS: On Developing a Raster Engine for Spatial DBMS
Schwarz and Seidel (2010): Fast Parallel Surface and Solid Voxelization on GPUs
Huang et al. (1998): An Accurate Method for Voxelizing Polygon Meshes
Some other good papers I've found are:
Zlatanova et al. (2016): Towards 3D Raster GIS: On Developing a Raster Engine for Spatial DBMS
Schwarz and Seidel (2010): Fast Parallel Surface and Solid Voxelization on GPUs
Do you render the voxels as unit cubes or do you create a smoother surface with something like marching cubes?
Provide a drawing on paper and some lego. Explain that there are different ways to arrange the lego on the paper to recreate the shapes, but however you do it, it's still going to look like lego.
xTr1m: There is no other way in this case than to use unit cubes.
psonice: Thanks, I tried something similar with pen and peper but maybe it will really help if I use actual Lego bricks.
psonice: Thanks, I tried something similar with pen and peper but maybe it will really help if I use actual Lego bricks.
Quote:
xTr1m: There is no other way in this case than to use unit cubes.
Then it'll always look shit.
Quote:
...but maybe it will really help if I use actual Lego bricks.
Or minecraft.
dunno about the speed/realtime requirements or what GPU is used but you can like render those cubes the size of a pixel and load more detailed data/do MC as mentioned above. surely any midrange GPU can render 2 million cubes still at a slightly acceptable FPS :)
Maali: We currently use 120x120x120 voxels, that is roughly 1.7 million. Depending on the size of the model that might make one voxel one pixel but it is not always the case. We chose this resolution as a good compromise between running time and quality of the result.
What I forgot to mention is that we also have a zooming function. So what appears to be one pixel in the preview can become something larger when you zoom in and so on.
our gpu voxeliser trivially does 512^3 on an animating mesh per frame in realtime these days
