🚀 go-pugleaf

In article <9311090618.AA27135@relay1.uu.net> Prabhat K Vaish
 <nicnet!GISD!pkv@UUNET.UU.NET> writes:
>
>My query to the netland is
>
>1. Why do we need 4 or more points to correctly define the transformation.
>
You have a possibility to check for errors, and you can estimate your
accuracy when you have more than the minimal number of points.

>2. How does accuraccy of tranformation improves with more no of points, when
>    only 3 points can be used to define affine transformations.
>
In general, your accuracy will be better by SQRT(n), where n is the number
of points minus the minimal number. So you may want to use 8-10 points
for the transformation - could result in inaccurate transformation
parameters, and more would not pay off in significant better accuracy.

Hope this helps
Wolfgang

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