Fitting on a sphere

[kai-uwe]

Hello,

i know that this has already been dicussed, but i still have problems in understanding this algorithm. i have to explain exactly how i get the radius and the centre of the sphere. can anybody tell me step by step what is going on?

thx

[RavensFan]

Please provide a link to wherever this has been discussed and what algorithm you are talking about.

Whatever that algorithm is, it's probably like linear curve fitting where you compare the data to a theoretical equation and try to minimize the sum of errors (or sum of square of errors) and determine the coefficients of the equation with a lot of calculus involved.

Message Edited by Ravens Fan on 01-23-2008 04:24 PM

[kai-uwe]

this topic has already been discussed here for example.

http://forums.ni.com/ni/board/message?board.id=170&message.id=149402&query.id=121336#M149402

the algorithm is called fitting on a sphere and in the LabView help you can find an equation for this, but i don't understand how i can get the value for the radius and the center from this equation.

[JoBa]

Hello kai-uwe,

in the thread you mentioned, altenbach has posted a link to a very thorough description of the inner workings of that algorithm in principle.

Not being a mathematician, I can't really explain it any better than this.

Maybe altenbach's example VI makes things clearer. It shows the algorithm for the 2D circular case, but it shouldn't be too hard to get an understanding for the 3D case from that if you are working with that kind of algorithms in your programs.

Regards,
Johannes

NI Germany   626396