Hi Chris,
Yes, the original coordinates aren't in WGS-84, they are UTM
coordinates for zone 17N.
That explains why the image doesn't match up, too, the projection of
the image doesn't match the projection of the map. The pixels of the
image have constant distance proportions, and WGS84 has constant
degree proportions.
This would also explain why the scale values are so different, too.
So to get the image to match perfectly, you'd need to re-project the
image. You can use gdal for that.
-- Don
On Jan 26, 2009, at 8:34 PM, Chris Allport wrote:
> 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 Wed Jan 28 2009 - 10:55:53 EST