Geek asks and answers

Search for saddle points in 3d elevation map

Given a three-dimensional height map (from a laser scanner), how do I find saddle points ?

those. something like that:

height profile

I am looking for all the points where the curvature is positive in one direction and negative in the other.

(These directions should not coincide with the X and Y axis. I know how to check if the curvature in the X direction has the opposite sign as the curvature in the Y direction, but this does not apply to all cases. Worse, the resolution in X differs from the resolution in Y)

enter image description here

Ideally, I am looking for an algorithm that can withstand some noise and only mark “significant” saddle points.

+5
source share
2 answers

, .

, < > ( ) . , , - , . .

( 8 ). , .

, . , . , , . - , .

2D 8 , . +/- 1 . ( ) , , .

, "", . : http://www.cs.jhu.edu/~misha/ReadingSeminar/Papers/Gyulassy08.pdf .

-

+2

( , )

-, . . , . x'Ax + b'x + c, A .

x = (A ^ -1) b/2. , .

A + ve -ve , x. A 2x2 , , , .

+1

More articles:


All Articles