Gasssian curv. of blobs discontinous?

Gasssian curv. of blobs discontinous?

Post by Hans Peders » Sat, 31 Dec 1994 12:46:15

Quote:>s   As the title says, I'm looking for a shareware or freeware
>graphic editor supporting all gif and bmp formats.  Thanx.


  I was playing around with some implicit surface stuff the other
day and was surprised to find that the Gaussian curvature of "blobs"
appears to be discontinous. Even simple examples such as a smooth peanut
defined from two gaussian potentials appear to have discontinuities,
(at least according to my code :) and this puzzles me a little as these
shapes look so smooth. On the other hand, it looks like the absolute
value of the Gaussian curvature is continous,
except from degenerate points where the gradient is zero (such as
the center point of a degenerate peanut/butterfly). I tested my
code on simple surfaces where the curvature can be computed from
a parameterization (ellipsoids and cylinders) and got the correct
result to 5 accurate digits (computed the principal curvatures
analytically by normalizing and differentiating the gradient and then
solving for eigenvalues).

  Havn't had time to give much thought to this, but I think it
is kinda fun and would appreciate any comments.

  Yours ignorantly - Hans


1. bez curv inters

Hello peeps,

Would anyone happen to know how to calculate the intersection point of two
bezier curve and/or how to calculate the new ctrl points of a curve which
has been cut at a certain point so as to retain the same shape but truncate
one or another series of points from n point to that end point?

Bit of a mouthful I know.


   Matt. W.
"Who knows, one day the horse may sing?"
[The views of A.P employees are not the views of A.P itself.]

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