Taxidriver2009-11-16 13:05:27

Hi everybody,

i have an question about bspline curve fitting with least squares method,

where

– min |A*x = B|, where x are the unknown control-points, and

– A is the basis matrix with dimensions N x M , where N is the number of

discretized points of my orginal curve, M is the desired number of

control-points,

– B are the matrix of discretized points ( 1, N, 1, 3)

BasisFunction-Matrix A will be generated with the householder-method,

– Knots are fixed, generated from the orginal curve, from 0…1, with the

first and last times of Order (you know what i mean),

My problem is, i have a solver where i can put in the parameters, but when i

scale my Matrix A with more Columns, e.g. with more control-points as my

orginal curve, the solver will throw an unhandled exception,

when i debug and take a look to the generated Matrix A, then the last

row-vector, has at the last Order-positions, an undefined value “-1.#IND” ,

like this,

Matrix 7 X 6 // means, 7 discretized points, desired control-points 6

Order 2

1 0 0 0

0 0

0.633787 0.345427 0.020786 0 0

0

0.254618 0.62267 0.122712 0 0

0

0 0.225531 0.72055 0.0539196 0

0

0 0 0.188748 0.736911

0.0743408 0

0 0 0 0.196459

0.664286 0.139255

0 0 0

0 -1.#IND -1.#IND

Can anyone help me, is it possible that the knot-vector is the reason for

that ? or is it ok that the basisfunction has this value , i mean, because

of this, the householder method does not compute the desired control-points

X as long as X is larger than the number of controlpoints of the orginal

curve.

thanks in advance!

Taxidriver

Spellucci2009-11-16 13:06:15

In article <44145943$1@news.bea.com>,

“Taxidriver”

looks as if the knot vector defining the B-spline basis is erroneous, since

the B-spline for the last knot couldn’t be evaluated correctly.

hth

peter

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