>
> A question that has bothered me however; if vectors are stretched to fit
the
> raster, what impact does this have on distance and area functions. If I
> measure distance off a map that has a raster image underlying it, I
presume
> the vector has probably been streched, and the resulting measurement is
> likely to be incorrect? Would this also apply to functions like buffer; if
I
> buffer a point that is underlain by a rester image, will the buffer
distance
> be calculated correctly?
>
Peter,
As far as I have understood it, the "vector" map is "adjusted" by an affine
transformation (rotation plus change of scale). There is no "local"
deformation and distances are not affected as long as the calculations are
done with the map coordinate system. I should think thus that you should not
have any worry about distance calculations and other operations that are
independent of the display scale.
But I have often noticed that MI does not follow always what seems to be
logical, and someone may find a way to puncture my balloon.
Jacques Paris
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