RE: [OpenMap Users] Alternate World File for Image Tile Layer?

From: Chris Allport <callport_at_dtiweb.net>
Date: Mon, 26 Jan 2009 20:34:19 -0500

Hi, Don, thanks for the response.

Here is the file that was delivered with the file (supposedly in WGS-84,
but appears UTM to me):
        1.500000
        0.000000
        0.000000
        -1.500000
        613756.000000
        3834059.000000

Messing around with the numbers (and info from the text file), I got it
to work with the following file:
        0.0000165
        0E-11
        0E-11
        -0.0000135
        -79.75880
        34.64214

But this is really rough and just roughly (very roughly) matches.

Chris


-----Original Message-----
From: Don Dietrick [mailto:dietrick_at_bbn.com]
Sent: Monday, January 26, 2009 6:25 PM
To: Chris Allport
Cc: openmap-users_at_bbn.com
Subject: Re: [OpenMap Users] Alternate World File for Image Tile Layer?

Hi Chris,

Hmm. Is your image in WGS-84 coordinates? What's the difference in
the changed values? I thought I was using those values correctly, it
works for the images I have, but I might have just gotten lucky.

- Don

On Jan 21, 2009, at 10:29 AM, Chris Allport wrote:

> The documentation for World File indicates that it receives
> information in the following format:
> - <the dimension of a pixel in map units in the x direction>
> - <rotation term for row>
> - <rotation term for column>
> - <the dimension of a pixel in map units in the y direction>
> - <the x coordinate of the center of pixel 1,1 (upper-left pixel)>
> - <the y coordinate of the center of pixel 1,1 (upper-left pixel)>
>
> The sample values are indicative of what I get in my world file when
> I purchase the image from an online source.
>
> However, when I use this file in my application (CADRG projection),
> it does not show up. The image appears if I change the format to:
> - x scale of image
> - rotation about x-axis
> - rotation about y-axis
> - y scale of image
> - top left latitude coordinate in decimal degrees
> - top left longitude coordinate in decimal degrees
>
> Of course, I lose the dimension and rotation parameters and my image
> is no longer properly registered.
>
> I am just wondering if there are any tips or tools within OpenMap
> that might help me, or if I am doing something else very wrong and
> need to fix.
>
> Thanks in advance for the help.
>
> Chris
>
> --
> Chris Allport
> Defense Technologies, Inc.
>
>



=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, openmap_at_bbn.com
BBN Technologies, Cambridge MA, USA
http://openmap.bbn.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


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Received on Mon Jan 26 2009 - 20:35:00 EST

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