volume rendering accuracy improvement request

[Jeremy Gill]

From Milton:

One small feature request comes to mind now that I’m able to do volume rendering again. I may have mentioned this before, but a small tweak to the transfer function GUI would help make it more useful, for me anyway. Basically, with all the noise in the microCT data, your lower and upper extreme values for the data set can vary quite a bit between similar samples. So when the control points on the horizontal axis are a fraction of that density range, it makes it impossible to set the same values for transparency % for a given density value. I would like to be able to set 0% transparency at 2000 units, 20% at 3000 units, etc.

I guess one could work around that by using a histogram to select everything below some value, maybe 0, and set it equal to 0. Then select everything above some upper limit, like 10000, and set it equal to 10000. Then the data range would be the same for all scans and you would have nice apples-to-apples comparisons with your volume renderings. If something like that were possible (maybe it already is and I missed it) in the volume rending page that would be super helpful.

Also, saving and loading LUTs on the render page doesn’t seem to work quite right. In some cases, it is able to load what I saved, but only the LUT itself, not the control points for the transfer function. In other cases, mostly if I have had several different files opened and closed, trying to load a previously saved setting seems to have no effect at all. Nothing is displayed in the log window when I try to load.