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Re: JPEG2000 Tiling Examples? [message #54302]

Thu, 07 June 2007 07:32

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On Jun 7, 1:19 am, Gaurav <selfishgau...@gmail.com> wrote:
> If any one has successfully implemented the tiling facility upon an
> image that has been warped onto a polygon object, kindly let me know
> cuz I am really stuck on this one.

I've been told that is not possible right now. There are feature
requests in this area, call ITT VIS and add your name if you are
interested.

Mike
--
www.michaelgalloy.com

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Re: JPEG2000 Tiling Examples? [message #54305 is a reply to message #54302]

Thu, 07 June 2007 00:19

Gaurav
Messages: 50
Registered: January 2007

Member

I think I came across a limitation to the tiling facility for JPEG2000
object. While all is quite well when you try and display the image in
a view by directly adding it to a model that is displayed in the view
(as in the demo program), things turn awry when the image object is
actually texture mapped onto a polygon object. Since the polygon
object may be in any orientation with respect to the view at the time
of reading of the image, tiles are simply NOT read even though the
program shown no error.

If any one has successfully implemented the tiling facility upon an
image that has been warped onto a polygon object, kindly let me know
cuz I am really stuck on this one.

Cheers!

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Re: JPEG2000 Tiling Examples? [message #54319 is a reply to message #54305]

Wed, 06 June 2007 06:52

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On Jun 6, 7:32 am, David Fanning <n...@dfanning.com> wrote:
> What I want to do is use the tiling feature to create
> an IDLgrImage that I can use as a texture on a polygon.
> I'm not sure *exactly* what I want. I just know that the
> original image is VERY big, and I thought to speed up the
> process by using lower resolution tiles as a stand in until
> the full resolution was absolutely required.

I have an article about basic widget program that tiles an IDLgrImage
(but not a texture on a polygon):

http://michaelgalloy.com/2006/04/15/idlgrimage-tiling-in-idl -62.html

Mike
--
www.michaelgalloy.com

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Re: JPEG2000 Tiling Examples? [message #54320 is a reply to message #54319]

Wed, 06 June 2007 06:32

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

David Fanning writes:

> Does anyone have an example of creating a tiled JPEG2000
> file? I am finding the documentation, uh, less than
> helpful. :-(
>
> Appreciate any help you can give.

Whoops! Quick fingers on that SEND button this morning!

What I want to do is use the tiling feature to create
an IDLgrImage that I can use as a texture on a polygon.
I'm not sure *exactly* what I want. I just know that the
original image is VERY big, and I thought to speed up the
process by using lower resolution tiles as a stand in until
the full resolution was absolutely required.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: JPEG2000 Tiling Examples? [message #54434 is a reply to message #54319]

Fri, 08 June 2007 03:49

Steven Houston
Messages: 5
Registered: November 2005

Junior Member

mgalloy@gmail.com wrote:
> On Jun 6, 7:32 am, David Fanning <n...@dfanning.com> wrote:
>> What I want to do is use the tiling feature to create
>> an IDLgrImage that I can use as a texture on a polygon.
>> I'm not sure *exactly* what I want. I just know that the
>> original image is VERY big, and I thought to speed up the
>> process by using lower resolution tiles as a stand in until
>> the full resolution was absolutely required.
>
> I have an article about basic widget program that tiles an IDLgrImage
> (but not a texture on a polygon):
>
> http://michaelgalloy.com/2006/04/15/idlgrimage-tiling-in-idl -62.html
>
> Mike
> --
> www.michaelgalloy.com
>

As Mike mentioned you cannot use a tiled IDLgrImage as a texture map on
an IDLgrPolygon.

If this doesn't rule out the use of a tiled IDLgrImage, then search the
IDL Help for "Preloading Tiles". At the bottom of that page there is a
section on how to load an entire low resolution version of your image.
This will be displayed until you read in the full resolution tiles.

Cheers,
Steve.

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Re: JPEG2000 Tiling Examples? [message #54440 is a reply to message #54434]

Mon, 18 June 2007 02:58

Gaurav
Messages: 50
Registered: January 2007

Member

Thanks a lot for the confirmation folks. I simply found a way round
the problem in the meanwhile. My application was such that I could
know the boundaries of the image in terms of lat/lon without actually
reading the complete image. What I did was to get this information for
small rectangular chunks of image in a 2D loop at using the region
keyword and then use these smaller images as complete images only if
it was useful.

But choosing an optimum tile size has been a problem and it still
causes upto 4 times the memory strain than reading just the right tile
would have caused. What would I have done without my 2GB RAM!

Cheers!

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