Re: Curve Fitting and Plotting

[Carlo de Falco]

On 29/set/08, at 09:46, Kearan Mc Pherson wrote:

> HI
>
> i am capturing two video streams of a moving cricket ball. one view  
> from the side and the other from above. after image processing i  
> obtain the two data.dat files. from here i want to do curve fitting  
> in order to achieve the data points/coordinates of the moving ball  
> in 3D. after this i want to plot the graph in 3D

Citing from wikipedia [1]

"In computer graphics, Catmull–Rom splines are frequently used to get  
smooth interpolated motion between key frames. For example, most  
camera path animations generated from discrete key-frames are handled  
using Catmull–Rom splines. They are popular mainly for being  
relatively easy to compute, guaranteeing that each key frame position  
will be hit exactly, and also guaranteeing that the tangents of the  
generated curve are continuous over multiple segments."

There is a catmullrom function in the "splines" pcakage on octave-forge:

>> pkg load splines
>> help catmullrom
 -- Function File: PP = catmullrom( X, F, V)
     Returns the piecewise polynomial form of the Catmull-Rom cubic
     spline interpolating F at the points X.  If the input V is
     supplied it will be interpreted as the values of the tangents at
     the extremals, if it is missing, the values will be computed from
     the data via one-sided finite difference formulas. See the
     wikipedia page for "Cubic Hermite spline" for a description of the
     algorithm.


     See also: ppval.

HTH,
c.

[1] http://en.wikipedia.org/wiki/Catmull-Rom_spline#Catmull.E2.80.93Rom_spline