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Thread Subject:
use 2d orthogonal projection to regenerate 3d curve ( not surface)

Subject: use 2d orthogonal projection to regenerate 3d curve ( not surface)

From: rahul

Date: 11 Jul, 2008 08:22:07

Message: 1 of 4

i have to take two images of a curve from orthogonal
directions.
than digitise the 2d data and use them to generate 3d curve.

the curve is very random ( so cannot be interpolated by the
usual interp1 functions).

i am digitising the curve using the ' getpts tool '.

i than, have 2 group of 2d data.
there is any algorithm to this thing ( 2 group of 2d data
to 3d curve)

any help in this regard will be greatly appreciated.

Subject: use 2d orthogonal projection to regenerate 3d curve ( not

From: rahulsahay81@gmail.com

Date: 13 Jul, 2008 04:59:33

Message: 2 of 4

On Jul 11, 4:22=A0pm, "rahul " <rahul_sah...@yahoo.com> wrote:
> i have to take =A0two images of acurvefromorthogonal
> directions.
> than digitise the2ddata andusethem to generate3dcurve.
>
> thecurveis very random ( so cannot be interpolated by the
> usual interp1 functions).
>
> i am digitising thecurveusing the ' getpts tool '.
>
% i think you r right.
now i have decided to take images of the curve form three angles ( 0,
45, 90).
these curve are very random . is there any algorithm to obtain the 3d
curve from these( 2d views) views.
thanks for any help
> i than, have 2 group of2ddata.
> there is any algorithm to this thing ( 2 group of2ddata
> to3dcurve)
>
> any help in this regard will be greatly appreciated.

Subject: use 2d orthogonal projection to regenerate 3d curve ( not surface)

From: Bruno Luong

Date: 13 Jul, 2008 08:40:19

Message: 3 of 4

"rahul " <rahul_sahay1@yahoo.com> wrote in message
<g5757f$af3$1@fred.mathworks.com>...

>
> the curve is very random ( so cannot be interpolated by the
> usual interp1 functions).

I have not read anything about that interp1 cannot perform
on "random" data (I guess you meant "noisy").

>
> i am digitising the curve using the ' getpts tool '.
>
> i than, have 2 group of 2d data.
> there is any algorithm to this thing ( 2 group of 2d data
> to 3d curve)
>
> any help in this regard will be greatly appreciated.

Assuming the two plane cuts along z-axis, and one plane y
x/y the other is x/z.

If for each x you can extract the y coordinate in x/y plane,
and similarly for x/z plane (for common x).

You now have (x,y(x),z(x)) coordinates.

What is the problem?

Bruno

Subject: use 2d orthogonal projection to regenerate 3d curve ( not

From: rahulsahay81@gmail.com

Date: 14 Jul, 2008 05:46:17

Message: 4 of 4

On Jul 13, 4:40=A0pm, "Bruno Luong" <b.lu...@fogale.fr> wrote:
> "rahul " <rahul_sah...@yahoo.com> wrote in message
>
> <g5757f$af...@fred.mathworks.com>...
>
>
>
> > thecurveis very random ( so cannot be interpolated by the
> > usual interp1 functions).
>
> I havenotread anything about that interp1 cannot perform
> on "random" data (I guess you meant "noisy").
>
>
>
> > i am digitising thecurveusing the ' getpts tool '.
>
> > i than, have 2 group of2ddata.
> > there is any algorithm to this thing ( 2 group of2ddata
> > to3dcurve)
>
> > any help in this regard will be greatly appreciated.
>
> Assuming the two plane cuts along z-axis, and one plane y
> x/y the other is x/z.
>
> If for each x you can extract the y coordinate in x/y plane,
> and similarly for x/z plane (for common x).
>
> You now have (x,y(x),z(x)) coordinates.
>
> What is the problem?
>
> Bruno
the problem is that point do not correspond. Interpolation is
difficult as the curve is random.
the curve even intersect itself few times.
correspondence is difficult to find.
thanks

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