VoxelView

• Platforms: SGI, Mac.
• WWW: http://www.vitalimages.com/vv.html
• Refs:
  • "Voxels: Data in 3D", Byte, May 1992 issue, pp177-182.
• Contact:

  	Vital Images
  	Fairfield, Iowa
  	Phone: 515-472-7726)
  	Email: bvz@vitalimages.com
  	

• Comments:
  • Mustafa Khokha: Vital Images writes its software so that it goes to the graphics hardware in the machine to do its voxel renderings. On machines like the SGI, this is great since SGI machines have fast graphics engines for just this sort of thing. The renderings are fast. I mean really fast. I was really amazed the first time that I saw it. This is a key part of both of these programs. If you have to wait many minutes for a rendering to occur, then a lot of the manipulations like opacity, lighting, and such become a lot (I mean a LOT) less useful. You learn so much more by being able to change these parameters on the fly. If you have to wait, forget it. I just don't have the patience to play with it, and I think you really lose a lot of "feeling" for what is going on in your datset. Therefore make sure that you get to try out a datset that is representative of the ones that you would be doing in terms of size and complexity. Then see if you can manipulate the settings (like lower the rendering quality) so that it renders before your eyes. Then when you see something interesting, up the quality and see if it really pans out. I know VoxBlast allows you to do this but I am not sure about VoxelView. This is because VoxBlast goes through the operating system when it makes its calls so they can "cheat" and render every other voxel or so. VoxelView doesn't because of its dependence on the hardware. On the other hand perhaps this is only true for the Unix versions? Anyway something to be aware of.

    Also one problem that we have with VoxelView is that you cannot have fractional spacing in the Z direction. In other words interpolations are purely whole numbers in the Z direction. This is a real drag since most of my datasets do not have aspect ratios that are whole number multiples in the z compared with x and y. Things may not look right then. Again this is because VoxelView depends on the graphics architecture and VoxBlast does not.

    Personally, for the short time that I tried VoxBlast, I thought it was quite nice. Everything is menu driven although you can if you want write your own scripts. Ease of use is not a problem. I would still compare with the Mac version that Vital Images makes though so be sure to get your hands on the demos.

  • Michael Cammer: VoxelView does do up to 16 bit renderings where bits can be grouped. We have tried the new color merging function for double immunofluorescence which allows for each dataset to be full eight bits.
  • Dietmar Reiter: I've got some minor experience on VoxelView Ultra on SGI, as well as on the Macintosh Version of VoxelView (which I know better, since our lab has got one). Three basic points are remarkable:
    1. Speed (and therefore interactivity) is minimal on the Macintosh release. It should be somewhat of an indication, what volume rendering SHOULD be on a graphics computer as the SGI. Speed lacks tremendously, what makes interacitve working with datasets (volumes) larger than 1 million voxels (a cube of 100x100x100 voxels) nearly impossible. It can be helpful to threshold out most of the voxels, in other words to keep the rendering task as minor as possible.
    2. Nearly no parameters of the VoxelView Mac can be given by numbers, but by fancy scroll bars. This inhibits for example an exact setting of the opacity for discrete voxel values. A manually cursor-drawn curve is the approximation.
    3. According to sources at Vital Images, the Macintosh version will not be developed further, what is understandable, because of hardware limitations of the 680x0 and the Mac PC system as a whole. This may probably change with the upcoming of the PowerPC. William VanZandt at Vital Images will give give more information.
  • Greg Gillen: It appears that NIH Image will open Voxel View PICS animation files and run them at a much faster rate than Voxel View. The only problem seems to be the LUT is messed up.
  • John Russ: [how you might be annotating your animations and if anyone has transferered animations to video for presentation at meetings] Yes - I use the mac version, which is a bit slow but OK on a Quadra. I save the animations as PICS files which I then convert to MooV format using ConvertToMovie. This lets me play them as Quicktime movies. I play them directly from a powerbook using an LCD overhead panel, not through videotape.