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

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:

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.

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

Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307