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Transformations
I have a transformation question from a recent post where I got help from migurski.
He gave me some help with the transformation calculations. I took his numbers and plugged them in and it worked great (in fact, I forgot the limit coords and it still worked). But now looking back, I don't see *how* it worked. Here are the numbers he gave me to plug into the calculator:
49, -130, 0, 0, 0
49, -120, 0, 1, 0
39, -120, 1, 1, 0
But I'm not understanding why the 0/1 for the rows and columns? Looking at the AC Transit example, those should be rows and columns of the image in pixels, right? In my case, my image is 256^2 at zoom 0. So my numbers were:
49, -130, 0, 0, 0
49, -120, 0, 255, 0
39, -120, 255, 255, 0
Which gives me a different calculation. Then, for my __bottomRightInLimit, looking at the Zoomify example, I get (I have 8 zoom levels):
new Coordinate(255, 255, 0).zoomTo(8)
But when trying this out I get nothing ... seems the wrong tiles are request (I haven't investigated much). Just curious as to what is going wrong?
He gave me some help with the transformation calculations. I took his numbers and plugged them in and it worked great (in fact, I forgot the limit coords and it still worked). But now looking back, I don't see *how* it worked. Here are the numbers he gave me to plug into the calculator:
49, -130, 0, 0, 0
49, -120, 0, 1, 0
39, -120, 1, 1, 0
But I'm not understanding why the 0/1 for the rows and columns? Looking at the AC Transit example, those should be rows and columns of the image in pixels, right? In my case, my image is 256^2 at zoom 0. So my numbers were:
49, -130, 0, 0, 0
49, -120, 0, 255, 0
39, -120, 255, 255, 0
Which gives me a different calculation. Then, for my __bottomRightInLimit, looking at the Zoomify example, I get (I have 8 zoom levels):
new Coordinate(255, 255, 0).zoomTo(8)
But when trying this out I get nothing ... seems the wrong tiles are request (I haven't investigated much). Just curious as to what is going wrong?
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Inappropriate?Hi,
It's not actually supposed to be the coordinates of the image pixels. Rather, it's the coordinates of the tiles that contain them - that's why we subtract 8 from the zoom level when calculating the values, it's like dividing by 256. There's a good walkthrough from Microsoft that describes their tile system coordinates, which might help shed some light on ours: http://msdn.microsoft.com/en-us/libra...1 Comment
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This answers the question
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Ah, that makes much more sense then. Thanks for the explanation!
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