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-   -   Normal to Line - Curve Equ. from Points (http://www.cfd-online.com/Forums/main/9450-normal-line-curve-equ-points.html)

A.S. July 4, 2005 07:25

Normal to Line - Curve Equ. from Points
 
Hi,

I have a 2d set of points, I want to get the curve equation, and then move points by some distances normal to the curve at that point. Can anybody point to some online literature on it.

Thanks

A.S.

Simon July 4, 2005 07:40

Re: Normal to Line - Curve Equ. from Points
 
I would suggest a spline interpolation, but if you use the routine from the "Numerical Recipes" book, what you get is the second derivative values to perform the interpolation as well as a routine to obtain the interpolated values. You can obtain the normal gradient to the surface from the first derivative: -1/df

zxaar July 4, 2005 20:34

Re: Normal to Line - Curve Equ. from Points
 
i belive i can help you, last week i wrote a small program to calculate the center of curvature for given 3d set of data representing a curve. i do calculate the normal vector in order to find the center of rotation, if u drop me a mail, i can modify my prog little bit to suit ur need and can mail u that.

(for example u might want to displace all the points by some fixed values or u might have corrosponding values in a file, or u might want to calculate them based on given curve).

write in detail.


A.S. July 4, 2005 23:39

Re: Normal to Line - Curve Equ. from Points
 
Hi Zxaar,

Thanks for your help.I will mail you the program. I is for 2d grid generation. It uses the Numerical recipies spline subroutine for interpolationing points. If you can help it will be very kind of you.

Thanks

A.S.

zxaar July 5, 2005 00:19

Re: Normal to Line - Curve Equ. from Points
 
or in 2d you can use this approach,

http://online.redwoods.cc.ca.us/inst...osculating.htm

my approach is similar to it but its in 3d.

A.S. July 5, 2005 02:41

Re: Normal to Line - Curve Equ. from Points
 
Zxaar,

Thanks

A.S.


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