World Files - Defining Image Rotation

[Guillaume Sueur]

Hi,

After some test, I confirm the right way to write tfw files for rotated
images is the one described here :
http://www.omg.unb.ca/~jonnyb/processing/geotiff_tifw_format.html
which I can sum up with :

first line of tfw file : pixel resolution * cos(rotation angle in radians)
2nd line : -pixel resolution * sin(rotation angle)
3rd line : -pixel resolution * sin(rotation angle)
4th line : -pixel resolution * cos(rotation angle)
5th and 6th lines still x and y of top left corner.

Hope that helps,

Happy holidays to all mapserver-users lists readers



Guillaume Sueur a écrit :
> Hi,
> 
> It doesn't help so much on the precise point of rotation parameters.
> I've had the same problem few days ago, and despite many tests I didn't
> manage to get a proper rotated image. I fixed that with a "solid"
> rotation, set into the image file. But I'm also interested by that approach.
> 
> What are the units of rotation parameters ? I think it's radians, but
> maybe directly cos and sin of angle in radian which would be more
> adequate tu use in the six parameters transformation...
> 
> Is it counter-clockwise (i.e. trigonometric) direction ?
> 
> is the first one x or y rotation term ? The ESRI support page
> (http://support.esri.com/index.cfm?fa=knowledgebase.techarticles.articleShow&d=17489)
> is useless.
> 
> the best info I've found are here :
> http://www.omg.unb.ca/~jonnyb/processing/geotiff_tifw_format.html
> 
> but I haven't tried yet.
> 
> Guillaume
> 

-- 
Guillaume SUEUR
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