20040701: A few bugs (we think) in IDV

>From: Richard Clark <address@hidden>
>Organization: Millersville
>Keywords: 200407011651.i61GpGWb029029

Hi Rich-

Thanks for forwarding these issues

>I've had four students working on IDV while I was at a LEAD meeting. I'm
>sending along the problems that they encountered. If you have any
>information that would help us overcomes these problems, it would be greatly
>appreciated.
>
>Here are the problems we encountered:
>
>- Saving and reloading capture files.  We are able to save the capture file 
>and reload it right away if the window is still up, but if we try to access
>the file after closing and reopening the idv program a error comes up saying
>"There was an error loading the data". Do we have to save, for example, the
>eta data to the hard drive and then access it from there?

The capture only will save events that occur during capture.  That
will include the event of loading a new data source, but it doesn't
know about existing data sources.  For now, you would have to
save the current state as a bundle and load it back in before
running the capture.  For the next release, we will look at
having the capture grab the bundle intially and reload it
before the playback.  Thanks for pointing this out.

>- Transparency.  When viewing the eta topographic data and then making it 
>transparent, the program doesn't always seem to react right away.  We found
>that we have to switch between "solid" and "mesh" and back to "solid" in
>order for the layer to become transparent.

Transparency is problematic in the IDV, Vis5D and Java 3D in general.
The problem is that there is no ordering to the shapes so your
mileage will vary depending on what you do.  In the IDV, it
ends up being dependent on the order in which you add data.
If you start up the IDV, load in some surface data (e.g., sea
level pressure), then add in the topography, you can change
the transparency on the topography and you will see the
isolines.  However, if you load in the SLP after the topography,
you will not see the isolines.  When you change the appearance
(i.e., mesh or solid) of the topography, you are actually
unloading and reloading the display, so it end up being loaded
in after the SLP and thus, transparency works.  In general, 
for transparency to work, it has to be on the last thing
loaded in.  (BTW, in testing this, I found another bug in the 
latest code which got fixed, so thanks for the test case!).
>
>-  Odd looking shapes on temperature at isobaric levels.  When the surface
>is made transparent what appears are these shapes that look like cold front
>segments scattered all over the surface. Attached is a bundle showing what
>we see.

Again, this is where you mileage with transparency varies.  Because
the triangles (shapes that make up the isosurface) are not sorted,
you sometimes see that zigzag effect. 

Sorry to say that I don't have a fix for the transparency problems.
On the upside, I am looking into a way to drape 2D fields over
topography, so then there wouldn't be the pressing need for
transparency.

Don
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