How to find curve corner points using JTS or NTS?

Question

I have a curve (say JTS edge):

How to find all curve direction change points that surpasses given angle using JTS (Java) or NTS (C#):

Answer 1

I did some research and made some tests on JTS, and the best way I found is:

• Create polygons and use the function union
• Then iterate over the Coordinates, and create a sub-array on each "hard angle" (negative scalar product) and when the sum of angle reaches 180 (don't take the last angle to avoid non-function issues)
• Then I change the base to an orthonormal base with x(firstElemOfSubArray, lastElemOfSubArray) by computing the base-changing matrix, and I then recompute the sub-array in a new coordinate system
• I then create a function using org.apache.commons.math3.analysis.interpolation.SplineInterpolator to interpolate the function of the course, and then I get the derivative and search the extrema (don't take elements with an ordinate that is too low). With its absysse you can find which point is an inflexion point
• So the point you search for are first elements of each sub array, and its inflections points (if there are any)