[Wrf-users] IDV and VAPOR

[Josh M. Gelman]

My experience has been similar to the other users' responses.  I found the IDV
to be quite useful for quick, on-the-fly plotting that requires very little
effort.  It is very user friendly, has plenty of customizable options (color
schemes, formulas, etc.), works very well in stereo (although you have to
modify the config file to do this), and has decent batch support.

VAPOR requires a little more time and effort when plotting fields.  Some prior
experience with other visualization packages such as Paraview would be helpful.
 But it also gives you many additional options and settings that are not
available in the IDV.  As a result, it might be more useful for looking at
specific phenomena that you are interested in, whereas the IDV might be useful
for getting an overview of an entire model cycle.  The stereo support in VAPOR
is okay, but it's manual (specifying a separation angle, left eye image, right
eye image, etc.).  This may be useful to some users, but if your video card and
software support splitting the images automatically, this can be a pain. 
That's why I preferred the IDV or Vis5D for stereo over using VAPOR.

The only other issue with the IDV is as others have mentioned, it's memory
intensive.  Anything that uses Java 3D will be.  If you try to plot 3D derived
fields from native WRF NetCDF files in the IDV...make a sandwich, take a nap,
and then when you come back...it should be ready.  This is because the native
WRF NetCDF grids are staggered and when you load them into the IDV, it does a
transform to pressure coordinates and also stores the native grid domain into
memory.  Then if you have many grid points, it slows things down even more
since it's resampling at each grid point.  If you can destagger the grids using
WRFPost or ARWPost, it definitely speeds things up.  I always converted from
NetCDF -> Vis5D, but you can also do it to GRIB and other formats as well.

I am looking forward to doing more work with VAPOR in the Fall, and I think it
could be very useful.  Since both projects are under active development, it's
likely improvements will continue.  Both are excellent pieces of software
though, and I think it's definitely worth learning both.

--Josh Gelman.

On Mon, Jun  2, 2008 05:34 PM, Leigh Orf <leigh.orf at cmich.edu> wrote:
>
"Mark Stoelinga" wrote:
>
>|   I'm curious about IDV and VAPOR, two relatively new
>|   visualization and analysis packages from UCAR (IDV from
>|   Unidata, first released in 2004, and VAPOR from NCAR/CISL,
>|   first released in 2006). I admit I haven't tried either of
>|   them, but from the web pages, they both look like great
>|   software packages, with much effort poured into them. I have
>|   seen a increasing discussion on the users' email list about
>|   both of these packages recently.
>|
>|   My first question is from a policy perspective: Why is UCAR
>|   developing two major visualization/analysis packages that, at
>|   first glance, seem to have many of the same capabilities?
>|
>|   I'm also curious about WRF users' experiences with these
>|   two packages. How seamless are each of these packages with
>|   ingesting native WRF system data? What are users' experiences
>|   with using these two packages for analyzing and displaying
>|   WRF system data? Has anyone used both, and has an opinion on
>|   relative strenghts and weaknesses?
>|
>|   Mark
>


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