voxels vs pixols ...... i care about your info.

michaelmoures

Hello there bros

i always wondering what is the difference between voxel and pixels ?
what i reached is ....again i could misunderstood  some informtion ...

pixols...is like what they use in zbrush . its a pixel with depth channel.it can have distortion  thats why they made zremesher  to make it equal quades ...and you dont need uv mapping to paint on it
  --- in my opinion i think it takes less ram memory than pixol ..but not sure about that


okay pixol .

i think sculptris and 3d coat both of them using pixol ...well its like quads but  but triandles  you know quads is like two triangles ..any way ..it has uniformal shape no distortions so u dont have to deal with voodo issues with geometry while u sculpting or cliping your mesh....but u need uv to paint on it


                                        well i think i finished my info please share yours if you care
                                                                

                                                                                  


 

EarthQuake

Voxels are a way to store a cloud of points in a grid pattern.

Pixols are an abstract concept invented by Pixologic that has little relevance to how most 3D artists actually use zBrush. It refers specifically to meshes/data placed on the canvas rather than the actual 3D models (zBrush calls these "tools"). The majority of work you would do in zBrush is based on sub-dividing traditional polygonal geometry, not pixols or voxels.

Zremesher is a tool to convert your polygonal mesh to a different polygonal mesh, but with more even/square topology which is better for consistent detail distribution.

Quads or triangles, that's neither here nor there.

From my understanding, where voxels are used in various 3D sculpting apps is more of a behind the scenes thing. You're not actually working with voxel data, rather the app sometimes uses voxel data to generate traditional polygonal meshes. Zbrush uses voxels to figure out how to remesh, and 3D coat uses voxels to figure out even geometric distribution, which allows you to sculpt without regards to topology.

blankslatejoe

Just to add to EQ's definitions, Voxels = "Volumentric Element", but I don't think it HAS to be gridbased, per say. Voxels can be used like EQ describes them, or as a helper for baking information to use in a renderer later (like Voxel based GI) or as a way to organize elements in a final game like Minecraft, OR as simple proxies for more complex data during rendering, like lightwave's old 90s voxel FX clouds stuff.  It's just a loose term for 3d datapoints, as far as I understand.

Pixels, on the other hand, are "Picture Elements", the 2d representation of the data--a pure 2d grid that can be either sent to the monitor as a final "show this on the screen" stream of data, or it can be saved statically in a 2d file like you would do in Photoshop.

Netther of those should be confused with Texels: Texels are "Texture Elements"--how GPUs handle 2d data stretched across 3d forms--this is why we use the term Texel Density when talking about texture resolutions in games.

Pixols, however, is just a weird term invented by Zbrush, only used in Zbrush (I think). I don't think it has any reserved place in core graphics technology.

EarthQuake

blankslatejoe said:but I don't think it HAS to be gridbased, per say.

Interesting, I'm pretty sure (but certainly could be wrong) that voxels are by nature grid based, or at the least that voxel data is typically structured in a grid pattern (I'm not aware of any practical examples of voxels structured in arbitrary space).

"A voxel represents a value on a regular grid in three-dimensional space." from: https://en.wikipedia.org/wiki/Voxel

For example, with the voxel GI, the voxels are arranged in a grid pattern. The geometry is essentially converted to simplified, voxelized copy which can then be used to do cone traces against. The grid arrangement is essential for LODs, as you can easily split or combine the voxels into consistent spaces, otherwise you would end up with gaps between voxels.

Various definitions do not directly state that voxels have to conform to a grid, however, I believe it's implied.

"(in computer-based modeling or graphic simulation) each of an array of elements of volume that constitute a notional three-dimensional space, especially each of an array of discrete elements into which a representation of a three-dimensional object is divided."

Anyway, that's my basic understanding of it, and I'm not graphics programmer so I very well may be wrong.

JedTheKrampus

Earthquake, you're correct as usual. Voxels are always gridbased but if you have them in a 3d texture for SVOGI-like things then they will also usually be mipmapped and stored sparsely on the GPU, meaning that parts of the 3d texture that were precomputed and relevant to the scene being rendered can be paged into the GPU from main memory and disk as needed, rather than requiring you to store them all (plus all of their mipmaps) on the GPU. This reduces the memory requirements by a lot, but not by enough for it to be practical in most cases.

blankslatejoe

"A voxel represents a value on a regular grid in three-dimensional space." from: https://en.wikipedia.org/wiki/Voxel

Interesting--I was thinking back to the late 90s Lightwave Voxel clouds, which were not grid-limited in anyway--although we're also pulling back into ancient memory here..and really those might have very little, or nothing, to do with modern understanding of the term? Or maybe just the end user interaction with them wasnt grid based and it WAS grid based behind the scenes...i have no idea :-)

EDIT: looked it up...looks like I was thinking of something called HYPERvoxels...which sounds a lot like a proprietary tech, not unlike our pixol friend from earlier in the discussion. Dunno if its even remotely related to current usage of the voxel term (perhaps it used/uses a grid of voxels for lighting data to then inform shading on particles or something...?). regardless, it was for prerendered stuff

JedTheKrampus

That's probably something like voxels+wavelets like Blender has for smoke simulation if I had to guess. I never really used Lightwave so I couldn't tell you for sure.