Volume Debugging Widget Help

Most people shouldn't need to use this widget. This widget shows the pecentage of triangles (voxels) drawn and the number of triangles per second. Thus one can see how fast the system is operating and the effect of changing the ABS and REL sliders. It also lets you enter override mode or leave override mode.

X/Y/Z Override

The X/Y/Z button determines (if Override is set) in which direction DAVE traverses and displays the volume data. Normally (when override is not set) DAVE determines whether to traverse the data from one XY plane (Z option) to the next, or from one YZ plane to the next (X option) or from one XZ plane to the next (Y option). This is done automatically and depends upon the viewing orientation of the volume data. The plane is chosen which is most perpendicular to the viewing direction (so that the viewer is less likely to see "between" the planes). As the volume rotates the traversal direction is constantly changing. (The corresponding X/Y/Z button in the Volume Debugging widget is NOT updated. These buttons only matter if the user selects the Override button.). When the Override button is selected (highlighted in yellow) then the traversal direction specified by the highlighted X/Y/Z button is the direction the system uses. "RGB Play" sets Z Override. "Default Values" unsets Z Override.

This override option probably only makes the most visible difference when in PLANES mode. In cubes mode it may do funny things. It is mostly for examining images in Planes modes. If, for instance, you want to display zslices and really have them be slices of constant z value then you will want to set Z override on.

Print Maps

This prints out the 256 entries in the Opacity and Brightness translation tables. This shows precisely how data values are mapped.

Print Normals

You have to ask Jeff what this does.

Print Cubes

You have to ask Jeff what this does.

Menu Items for Producing Z buffer images (for stereo)

You can use DAVE to produce a sirds image (single image random dot stereogram). These are those nifty images you see in the mall a lot. It lets you see a "3D" image from only one printed image. This may be a useful way to get a stereo image published in a journal. To produce a sirds image you have to write out a "z buffer" image of what you see in the main drawing window. This is an image where each pixel has its depth in the scene written out instead of its color. Once the zbuffer image is written out use ~lml/vision/bin/sirds or its related programs to convert it into an image which can be printed on the laser printer (if black and white) or the dye sublimation or ink-jet printer (if color).

Z buffer filename...

Lets you specify the path and name of the zbuffer image. If this is not specified the default is the directory you started DAVE from, and the file name is "zbuffer.i2i".

Write Main Window Zbuffer

When chosen, this actually causes the zbuffer to be written out. Note: volume data (as opposed to surface data, from an input pts file or from the volume_to_suface widget) does not normally produce a zbuffer image which can be written out. See below.

Toggle Z Buffer

Volume data (as opposed to surface data, from an input pts file or from the volume_to_suface widget) does not normally produce a zbuffer image which can be written out (it slows down volume rendering). If you want to write out a zbuffer image of volume data you must choose this item prior to drawing the image of interest. Note: very dark voxels are drawn almost transparently by DAVE. Yet their existence will affect the zbuffer. To see more accurately what the volume data will produce, set Opaque Data on in the Edit Volume widget's menu and set your background color to nonblack (Edit Bkgnd Color from the Master widget). To eliminate some of these dark voxels move the left brightness slider up.

Toggle Z Buffer Scaling

When this is off, the depth of the scene is scaled so that the closest point in the scene is as close as possible and the background in the scene is as far away as possible. When this is on, the closest point in the scene is scaled to be a close as possible, and the farthest point in the scene (EXCLUDING the background) is scaled to be almost (so as not to touch the background) as far away as possible. In other words, this scales your scene to take maximum advantage of depth resolution. It would normally be chosen.

Toggle Short Output

Take this option off if you want to produce a large sirds image (which is done by pasting together a bunch of smaller images). When chosen, the zbuffer image which get written out (when "Write Main Window" is picked) is made up of short integers. This is our standard i2i image format. When this if off, a floating point zbuffer image is written out. The numbers are not actually floating point, but the are 4 bytes (ie, twice as long as a short int). When a floating point zbuffer image is written out,it is not rescaled at all. This permits you to write out several such zbuffer images. Then run ~lml/invitro/sirds/rescale_zvalues on the images. By rescaling them all together, we can eventually paste the resulting sirds images up next to each other to produce one large collage. The images which you write should be of field of views which just touch each other. To do this, take your first image then press the translate button on the master widget 10 times. This will get you to a view just touching the previous view.
Copyright 1995 by Lawrence M. Lifshitz and the University of Massachusetts Medical School. All rights reserved.