comp.lang.idl-pvwave archive: archive » Re: opening and display large file

Home » Public Forums » archive » Re: opening and display large file

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: opening and display large file [message #21569 is a reply to message #21548]

Wed, 30 August 2000 00:00

Martin Schultz
Messages: 515
Registered: August 1997

Senior Member

Sylvain Carette wrote:
>
> Hi
> How do you manage to display very large images? What is the
> options?
> From the manual, it seem that using "assoc" is a winner but
> maybe with one little example it would be more clear how can
> this be (It seem to me that it is an important aspect of
> programming with IDL since most of the time you'll deal with
> larger than memory files).
> Even with assoc, dont you still have to copy from the file to
> an array before display?
> I dont decipher exactly why and when to use readu or
> read_binary, the file pointer, assoc or writing to an offscreen
> buffer.
>
> I tried to open and display a GTOPO30 tile (4800 x 6000 int).
> tv could not display it - froze. I tried "slide_image" but it
> didnt scroll with "retain=1" while "retain=2" and "retain=3"
> result in windows error and crash.
>
> Since most of my data fall in the 30mb to 610 mb range, I need
> absolutely to open and display very large file. What is
> available? Pointers, sample code, library, ideas, etc, I'm
> listening.... Just knowing that it have to be handled on your
> own or that IDL provide facility (that they forgot to explain
> in the manual) to deal with this will already be invaluable
>
> Thanks
>
> Sylvain Carette
> VRML designer-composer
>

One option is to look into scientific data formats like netcdf.
This won't decrease your file size, but you can directlt access
portions of the data without having to read the whole thing
first, and there are tools available (NCO) which allow you to do
some averaging etc. offline and thus create a smaller file that
will fit.

Martin

--
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[ [[[[[[[
[[ Dr. Martin Schultz Max-Planck-Institut fuer Meteorologie
[[
[[ Bundesstr. 55, 20146 Hamburg
[[
[[ phone: +49 40 41173-308
[[
[[ fax: +49 40 41173-298
[[
[[ martin.schultz@dkrz.de
[[
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[ [[[[[[[

Report message to a moderator

[Message index]

		Re: opening and display large file By: Martin Schultz on Thu, 31 August 2000 00:00
		Re: opening and display large file By: Sylvain Carette on Wed, 30 August 2000 23:13
		Re: opening and display large file By: Craig Markwardt on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Sylvain Carette on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Kelly Dean on Thu, 31 August 2000 14:52
		Re: opening and display large file By: Sylvain Carette on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Kelly Dean on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Craig Markwardt on Wed, 30 August 2000 00:00
		Re: opening and display large file By: R.Bauer on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Martin Schultz on Wed, 30 August 2000 00:00
		Re: opening and display large file By: Nando Iavarone on Wed, 30 August 2000 00:00
		Re: opening and display large file By: promashkin on Thu, 31 August 2000 08:33

Previous Topic:	Gridding options
Next Topic:	IDL EPA Exam Test Question

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 07:15:28 PDT 2025

Total time taken to generate the page: 0.88097 seconds