Re: Fuzzy iso volumes

Hi Ken-

Ken Mankoff wrote:

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).

Oops, thanks for pointing that out.  We'll add an entry.

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.

You currently can't interpolate the transparency like you can the
colors, but it's a good suggestion.  I'll add it to the list.

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

The "To Front" solved that as you noted in your other mail.
Transparency is order dependent (unfortunately).

Don
*************************************************************
Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
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