RE: slow 2d image generation

• To: <tomw@xxxxxxxxxxxxx>
• Subject: RE: slow 2d image generation
• From: "Jim Cookas" <James.M.Cookas@xxxxxxxx>
• Date: Tue, 6 Jan 2004 15:59:58 -0600

tom

bingo!

works great...the image loads super-quick and looks good (no more 
triangles)...thanks so much for the help!

jc

> -----Original Message-----
> From: Tom Whittaker [mailto:tomw@xxxxxxxxxxxxx]
> Sent: Tuesday, January 06, 2004 3:33 PM
> To: Jim Cookas
> Cc: Jim Koutsovasilis; visad@xxxxxxxxxxxxxxxx
> Subject: Re: slow 2d image generation
> 
> 
> Hi Jim...
> 
> Sorry, I missed typed last night.  You should use parentheses 
> for the range 
> values.  The square brackets are used for options [units, 
> miss, etc].  See 
> section IIIb of the README.text file.
> 
> Please let me know if you have any more problems with this.  
> (Especially since 
> I always use comma-separated values... ;-)
> 
> tom
> 
> 
> Jim Cookas wrote:
> 
> > 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
> > 
> > 
> 
> -- 
> Tom Whittaker (tomw@xxxxxxxxxxxxx)
> University of Wisconsin-Madison
> Space Science and Engineering Center
> Cooperative Institute for Meteorological Satellite Studies
> Phone/VoiceMail: 608.262.2759
> 
>