tom, all
thanks a ton for the suggestion...it looks like this will be the method of
choice for speeding up image display...i implemented the changes today, but i'm
having a problem getting the image to display...i think it is a problem with my
ascii file format...
i am using tab-spaced values...here is what test.tsv looks like:
(Down_Range,Cross_Range)->(RCS)
Down_Range[-755.383:755.383] Cross_Range[-755.383:755.383] RCS
[ 256 RCS values for Down_Range #0 ]
[ 256 RCS values for Down_Range #1 ]
.
.
.
[ 256 RCS values for Down_Range #255 ]
when i try to load this file into visad, i get these messages at the terminal:
Unit name problem:visad.data.units.ParseException: negative sign follows
decimal point with -755.383:755.383
Unit name problem:visad.data.units.ParseException: negative sign follows
decimal point with -755.383:755.383
any ideas on the problem?...thanks again!!
jc
> -----Original Message-----
> From: Tom Whittaker [mailto:tomw@xxxxxxxxxxxxx]
> Sent: Monday, January 05, 2004 9:43 PM
> To: Jim Cookas
> Cc: Jim Koutsovasilis; visad@xxxxxxxxxxxxxxxx
> Subject: Re: slow 2d image generation
>
>
> Jim:
>
> I believe that part of the slowness in "reading" is that the form of
> your data is producing an IrregularSet, which VisAD needs to
> "triagulate" when it does the display. If your data points are a
> "regular grid" (meaning, regular/constant spacing between
> data points)
> you can use the format:
>
> Down_Range[-755.383:-200], Cross_Range[-755.838:-500], RCS
>
> (where the '-200' and '-500' should be the actual ending
> values for the
> sample domain. If you do this, and then put all the RCS
> values (along
> the Cross_Range)for a single Down_Range on one input line. The text
> reader will compute the actual domain sampling coordinate for
> each "RCS"
> value. When you do this, the TextAdapter will make a
> Gridded2DSet for
> the sampling domain, and it is handled faster than the IrregularSet.
>
> Of course, there will be some overhead for reading and
> decoding the text
> in either case, so I agree with JimK -- you may want to
> create your own
> reader.
>
> tom
