Fw: Position tracking

Hi Teis,
This might help you: A reply of Kato to a previous query.

Kasim

----- Original Message -----
From: "Hirokazu Kato" <kato@s ........................>
To: "Stuart" <stuart@t ............>
Cc: <artoolkit@h ..................>
Sent: Thursday, October 03, 2002 5:17 AM
Subject: Re: Position tracking

> Hi,
>
> >What I'm asking is this: am I correct in thinking that it's possible to
> >use the libraries to determine the camera's position given that you know
> >the exact positions of the markers?
>
> Actually, ARToolKit calculates marker position in camera coordinates
> by 3x4 transformation matrix. In order to get cmera position in marker
> coordinates, you have to invert the matrix. This inverted matrix
represents
> transformation from camera to marker. therefore translation component of
the
> matrix means camera position in marker coodinates.
>
> >Am I also correct in thinking that arDetectMarker() and arGetTransMat()
> >will enable me to extract the positional data of the camera, given that I
> >know the locations of the markers in the physical world?
>
> You have to take care of the accuracy.
> Basically ARToolKit is designed for image overlay.
> It is not designed for 3D measurement system.
> Anyway you have to calibrate your camera very carefully.
>
> --
> ------------------------------------------------------------------
>   Hirokazu Kato
>   Faculty of Information Sciences
>   Hiroshima City University               Phone: +81-82-830-1705
>   Email: kato@s ........................     Fax: +81-82-830-1435
>   URL: http://www.sys.im.hiroshima-cu.ac.jp/people/kato/

From:	"Kasim Rehman" <kr241@c ........>	Received:	Dec 15, 2002
To	"Teis Draiby" <teis@d .........>, artoolkit@h ..................
Subject:	Fw: Position tracking
Hi Teis, This might help you: A reply of Kato to a previous query. Kasim ----- Original Message ----- From: "Hirokazu Kato" <kato@s ........................> To: "Stuart" <stuart@t ............> Cc: <artoolkit@h ..................> Sent: Thursday, October 03, 2002 5:17 AM Subject: Re: Position tracking > Hi, > > >What I'm asking is this: am I correct in thinking that it's possible to > >use the libraries to determine the camera's position given that you know > >the exact positions of the markers? > > Actually, ARToolKit calculates marker position in camera coordinates > by 3x4 transformation matrix. In order to get cmera position in marker > coordinates, you have to invert the matrix. This inverted matrix represents > transformation from camera to marker. therefore translation component of the > matrix means camera position in marker coodinates. > > >Am I also correct in thinking that arDetectMarker() and arGetTransMat() > >will enable me to extract the positional data of the camera, given that I > >know the locations of the markers in the physical world? > > You have to take care of the accuracy. > Basically ARToolKit is designed for image overlay. > It is not designed for 3D measurement system. > Anyway you have to calibrate your camera very carefully. > > -- > ------------------------------------------------------------------ > Hirokazu Kato > Faculty of Information Sciences > Hiroshima City University Phone: +81-82-830-1705 > Email: kato@s ........................ Fax: +81-82-830-1435 > URL: http://www.sys.im.hiroshima-cu.ac.jp/people/kato/