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Re: Array indices and lookup tables [message #39714 is a reply to message #39713]

Thu, 10 June 2004 06:11

Haje Korth
Messages: 651
Registered: May 1997

Senior Member

Christopher,
oops, you are right, the 360 should have been a 720. I have worked with
triangulate and trigrid in the past and what I learned is that you do NOT
use these in time-critical operations. This is even slower than looping
through a lookup table.

Cheers,
Haje

"Christopher Lee" <cl@127.0.0.1> wrote in message
news:20040610.093904.771151432.32286@buckley.atm.ox.ac.uk...
> In article <ca72v6$qlb$1@aplcore.jhuapl.edu>, "Haje Korth"
> <haje.korth@jhuapl.edu> wrote:
>
>
>> Good morning all,
>> I am working on a coordinate transformation for a map and I have a
>> simple problem. My mind is alreay blocked early in the morning and I
>> could use some input: I have an rgb image of dimensions [3,1440, 720]. I
>> need to rearranged the pixel in the image according to a lookup table of
>> dimension [2,1440,360], which contains the column and row of the new
>> pixel assigned to a location. Is there a magic way to do this without
>> looping through each pixel in IDL?
>> Thanks for helping,
>> Haje
>>
>
> The lookup table....Why is there only 360 points in the third dimension,
> not 720?
>
> I'm assuming the dimensions go as:
> 1st: [column, row]
> 2nd: new X location
> 3rd: new Y location
>
> If the 2nd and 3rd dimensions are the location of the point in the new
> image then you have a list of 1440*360
> points linking the old coordinates to the new grid?
>
> TRIANGULATE and TRIGRID should work then? using the XOUT and YOUT
> keywords to set your output grid.
>
>
> Chris.

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[Message index]

		Re: Array indices and lookup tables By: David Fanning on Thu, 10 June 2004 06:59
		Re: Array indices and lookup tables By: David Fanning on Thu, 10 June 2004 06:57
		Re: Array indices and lookup tables By: Haje Korth on Thu, 10 June 2004 06:11
		Re: Array indices and lookup tables By: Chris Lee on Thu, 10 June 2004 01:39
		Re: Array indices and lookup tables By: Haje Korth on Wed, 09 June 2004 07:49
		Re: Array indices and lookup tables By: David Fanning on Wed, 09 June 2004 07:26
		Re: Array indices and lookup tables By: Haje Korth on Wed, 09 June 2004 07:06
		Re: Array indices and lookup tables By: David Fanning on Wed, 09 June 2004 06:42
		Re: Array indices and lookup tables By: Chris Lee on Thu, 10 June 2004 10:15

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