define: voxel

A voxel is the 3D equivalent of a pixel. So, where a pixel is the smallest sample element in a 2D image, the voxel is the smallest sample element in a volume image. The word “voxel” is a combination of “volumetric” or “volume”, and “pixel”.

“Some alternative 3D rendering techniques use voxels to render 3D scenes: whilst it is not a common technique within real-time 3D at the moment, with the increasing power of computers, it will probabally become more important in the future.” ((http://www.machinima.com/article.php?article=69))

cube

April 30, 2007. computers/programming, words. 3 Comments.

3 Comments

  1. Bonzo replied:

    I ain’t no 3-D renderer, and I’m unfamiliar with their lingo, but “voxel” bugs me. When I first heard it, I assumed it was a the smallest unit of an *audio* file, because
    vox = voice

    I propose that 3-D renderers give “voxel” to the audio engineering community and starting using the word “boxel” instead.

    May 1st, 2007 at 2:53 pm. Permalink.

  2. Ivan replied:

    From an email exchange:
    I was just thinking about how voxels are used in robotics. The state
    of the art in robotics is much worse than hollywood would have you
    believe.

    Just reasoning about the environment, moving around, and avoiding
    obstacles is hard. Think about a roomba (i work at iRobot) — it
    doesn’t know anything about it’s environment — just bouncing around.

    If you had a voxel representation of the environment, you could avoid
    obstacles and plan paths. You probably want to do this in a metric
    representation.

    A more efficient representation might include voxels, but with a
    quad-tree structure to have different sizes. An example might be big
    voxels for empty space or the space inside structures like buildings
    http://www.gamedev.net/reference/articles/article1485.asp

    I suppose I assumed homogeneous size.

    Ivan
    – Hide quoted text –

    On 5/1/07, Anita Lillie wrote:
    > Ivan,
    >
    > Thanks for your email. I appreciate comments like this, since it’s
    > important that I put things in proper perspective.
    >
    > I certainly didn’t mean to suggest that voxels are the most efficient
    > way to represent any volume, just as storing and manipulating pixels
    > is not the best way to represent any 2D image. The page I quoted has
    > to do with real-time 3D in gaming, where voxels are indeed being
    > used. Also, I’m wondering, can you tell me why you think of a voxel
    > as a cubic centimeter, millimeter, or any particular size?
    >
    > You’re welcome to post your message as a comment on my blog entry!
    >
    > Thanks,
    > Anita
    >
    > On May 1, 2007, at 4:27 PM, Ivan Kirigin wrote:
    >
    > > Hi,
    > >
    > > I work in robotics & computer vision.
    > >
    > > We in the field often try to represent 3D objects. The Best Thing
    > > quoted: “whilst it is not a common technique within real-time 3D at
    > > the moment, with the increasing power of computers, it will probabally
    > > become more important in the future.”
    > >
    > > That isn’t true.
    > >
    > > Think about the space around you. Let’s say 20meters tall, and a few
    > > hundred meters on each side. You can visualize that space in your mind
    > > right now, right? It probably involves a few streets. Subdivide it
    > > into cubic centimeters. That’s 800 billion voxels.
    > >
    > > Manhatten is taller than 20 meters. Let’s say 500m ( > 3km wide and 20km tall. That’s 1,200,000,000,000,000 voxels, over a
    > > quadrillion.
    > >
    > > There are much more efficient ways to represent 3D structures of that
    > > size. There is no reason to forgo efficiency as computers get better.
    > >
    > > For fun: millimeter scale voxels and a more accurate measure of
    > > manhatten (87km^2) yield 43 quintillion voxels.
    > >
    > > Here is a paper on efficient voxel ordering & data structures for 3D
    > > scene processing
    > > http://www.ri.cmu.edu/pubs/pub_5408.html
    > >
    > > Here is one about actually processing the data to classify things like
    > > tree trunks
    > > http://www.ri.cmu.edu/pubs/pub_5611.html
    > >
    > > Ivan
    > > http://www.kirigin.com
    > >
    >
    >

    May 2nd, 2007 at 9:14 am. Permalink.

  3. Ivan replied:

    A tesseract is a 4D cube. How about we define a texel like a pixel and voxel?

    That would assume the forth dimension is like space.

    A space-time 4D cube could be a stixel.

    Ha!

    Keep it going:
    http://en.wikipedia.org/wiki/Penteract

    May 2nd, 2007 at 9:14 am. Permalink.

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