Re: Fuzzy iso volumes

Hi Don,

On 2007-05-24, at 12:35 , Don Murray wrote:

Hi Ken-

Ken Mankoff wrote:
I've browsed the manual and think the answer to the following question is 'no' (at least I didn't see any screenshots that showed this) but want to
check here.
Can IDV do transparent iso volumes rather than hard iso surfaces. Sample
screenshot of what I'd like to do in IDV is here:
http://edgcm.columbia.edu/~mankoff/fuzzy_volume.png
I know IDV can do the gray iso surface, but what about the yellow/ blue?

You could do this with a combination of the Volume Rendering
control and an isosurface.  Set the transparency on the volume
rendering to be about 90%. You'll also need to use the View->To Front
option for the Volume control to be able to see the embedded
isosurface.

OK I forget about Volume Rendering (FYI that string isn't even in the manual). I've done that. By default, I cannot see through the top layer, so I set the transparency of the colorbar. Example screenshot is here:

http://edgcm.columbia.edu/~mankoff/IDV.png

But there is a difference between this and the previous image. In the original image, transparency is a function of data value (in addition to color). What I've done in IDV has color as a function of value, but transparency is just applied to the whole data set uniformly.

I chose 50% transparency in the above image. For this specific image it looks like since there are 4 layers that each layer is 12.5% opaque (87.5% transparent). The four layers therefore are 50% transparent as a total.

Is there a different way to get transparency applied to the data set as a function of the data set? For example, looking at a rain cloud, I'd like to color the data based on moisture content, but have transparency based on particle density. This would give a somewhat realistic view, in that when there are more particles it gets harder to see through a cloud.

Also, on this image, I've added an isosurface, but I cannot see it through the 'transparent' volume layers.

http://edgcm.columbia.edu/~mankoff/IDV.png

   -k.