Re: Contour plots

[Daniel J S. <dan...@ie...>]

Hans-Bernhard Broeker wrote:

>
>> Of course, the optimum thing to do is to pick the location on the 
>> level curve that is furthest from it's neighboring level curves.  It 
>> has to work on general data, so gradient or such would be out.  
>
>
> But the discrete gradient wouldn't be.
>
> Remember that contours are based on a grid dataset, which actually has 
> been cut into triangles in the x/y plane.  The contour curve is made 
> from edges cutting through such triangles.  The gradient of the 
> triangle can be used as a reasonable approximation of the surface 
> gradient.


That might be good.  If the minimum gradient were chosen, the locations 
of the annotation (enumeration?) would likely strike out a nice looking 
curve.  However, there would probably have to be a rule that picking 
such a minimum (actually we're talking minimum of the gradient 
magnitude) requires not only the minimum, but an "epsilon tolerance" for 
which to surpass the current gradient magnitude minimum.  Otherwise, for 
simple curves like ellipses, with symmetry, the text might bounce back 
and forth across the curve according to the bit noise of computations.

Dan