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[IDV #HHW-968552]: custom made gridded netCDF files for visualization by IDV

Hi Randy-

> ok, we are running IDV 2.3 with 3gig of heap

Does the memory monitor show that you are using 3 Gb?

> when we read the file in and try to plot an isosurface
> we get:
> java.lang.OutOfMemoryError: Java heap space
> java.lang.OutOfMemoryError: Java heap space
> java.lang.OutOfMemoryError: Java heap space
> java.lang.OutOfMemoryError: Java heap space

I was hoping there would be some sort of stack trace
showing where the error first occured before you get
the OutOfMemoryError.

As for the size issue, storage of data is different from
usage of the data.  To have a working object in memory that
has a geo-relation between every value so we take the data 
and form a structure like:

(lat,lon,alt) -> (param)

We expand the byte data (param) to floats, but in the end for a volume,
we have the number of points times 4 (lat,lon,alt,param) times
4 bytes per value.  Then, to transform the data into an isosurface,
there is additional overhead in memory during color lookup, triangle
creation and transform to the projection.

Don

> 
> 
> --- Unidata IDV Support <address@hidden>
> wrote:
> 
> > Hi Randy-
> >
> > > We have generated a .nc file which contains one
> > > variable (liquid water) that we are trying to
> > > visualize in IDV. The dimension of the grid is
> > > 1250x1250x50. We get a exceeds maximum heap size
> > > (which we defined to be 3gig). The file is only
> > 75mb
> > > but yet IDV seems to be using 3 gigabytes of
> > memory
> > > before we get the error. We assume we are doing
> > > something wrong.
> >
> > Can you send along the error stack that you are
> > getting?
> > I get an error just trying to make the grid because
> > for
> > every point in the domain, there are three 4 byte
> > (float) values
> > (latitude, longitude and altitude) which ends up
> > being over
> > 900 mb (78125000*3*4) and my heap is only 1 Gb.
> > However, I suspect you
> > are getting bit further on down the line when the
> > rendering
> > is occurring so it would be good to know where that
> > is.  You
> > also have to add in 4*78125000 bytes for the values
> > themselves.
> >
> > If you subset the grid using the stride widget to
> > take every
> > other or every third point, you should be able to
> > create
> > an isosurface.
> >
> > Also, what operating system are you running the IDV
> > on and
> > what version are you running?
> >
> > > Can you load it on your system? To access the file
> > > goto:
> > >
> > > the files are called: AZ.000000000.nc and
> > > AZ.000000001.nc
> >
> > Thanks for the samples.
> >
> > Don
> >
> > Ticket Details
> > ===================
> > Ticket ID: HHW-968552
> > Department: Support IDV
> > Priority: Normal
> > Status: Open
> >
> >
> 
> 
> 
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Ticket Details
===================
Ticket ID: HHW-968552
Department: Support IDV
Priority: Normal
Status: Open