Graham Davis a écrit :
> I am using the value of 2 degrees with 10 points. Is there documentation
> anywhere that explains the variance of using higher/lower degrees with
> more/less points?
Not as fas as I know. The javadoc for the WarpTransform2D constructor gives the
minimal amount of points, but empirical experiments suggests that we need quite
more points than the declared minimum to get good result.
For a degree 2, the minimum is 6 points. It seems to me that 10 points should be
enough, but it may be worth to try more.
> Anyways, I appreciate the help. Should I be using a different value for
> the degrees? Could that really flip the result upside down?
I would suggest to try a degree 1 first (which is basically an affine transform)
with the 10 points. Then increment the degree progressively, but I would not
suggest to go higher than 4 degrees (2 is probably enough).
However the image should not be upside down. Or maybe this effect appears
because pixel coordinates are increasing down while geographic coordinates are
incresing up. An easy fix would be to replace y values by (height - y).
Could you post your source and target coordinates please?
Martin
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