ARToolKit | Mailing List Archive |

Again: about using multiple markers for tracking

From: | Maia Engeli <maia@e ......> | Received: | Oct 25, 2003 |

To | <artoolkit@h ..................> | ||

Subject: | Again: about using multiple markers for tracking | ||

Dear all, regarding ARMulti: I am having the same questions as Enrico, mainly this one: > what does the matrix relative to each marker (in marker.dat) describe? I have markers on walls, which should serve as a background to calculate the camera position in a global coordination system. Similar to the shared white board described in www.sys.im.hiroshima-cu.ac.jp/people/kato/publications/c-99.IWAR99.pdf , but on three sides. Just one simple example of how to use the matrix would be of great help. #marker 1 Data/multi/patt.a 40.0 0.0 0.0 1.0000 0.0000 0.0000 0.0000 0.0000 1.0000 0.0000 0.0000 0.0000 0.0000 1.0000 0.0000 Thanks - Maia |

From: | =?ISO-8859-1?Q?J=FCrgen_Zauner?= <jzauner@f ..............> | Received: | Oct 27, 2003 |

To | artoolkit@h .................. | ||

Subject: | Re: Again: about using multiple markers for tracking | ||

Hi, the simple example is already given in the ARToolKit example. Ok, lets have a more detailed look at the marker.dat file. It describes a set of markers plus a offset transformation for each marker. This offset transformation is applied to the transformation matrix of the detected marker. The result is a referenze coordinate system for all these markers. This means if we detect one of the defined markers then we always get this coordinate system. If we want to define a new multi marker then we have to define this reference coordinate system. In marker.dat the marker Data/multi/patt.a is such a reference coordinate system, because the transformation is the identity matrix. If we take a closer look at the other markers we will see that: * Data/multi/patt.b is translated 100 along the x-axis * Data/multi/patt.c is translated 200 along the x-axis * Data/multi/patt.d is translated -100 along the y-axis * Data/multi/patt.g is translated -100 along the y-axis and 100 along the x-axis * Data/multi/patt.f is translated -100 along the y-axis and 200 along the x-axis So, all these markers are placed by the given offset transformations. For the MR assembly instructor (presented at ISMAR03) we use a similar approach and we automatically calibrate these transformations. Just by detecting one of the already defined markers and calculating the tranformation between the reference system and the new marker. I hope my explanation helps a little bit. Best regards, Juergen Zauner ============================================ Upper Austria University of Applied Sciences Department of Mediatechnologies and -design Hauptstraße 117 A-4232 Hagenberg AUSTRIA |

From: | Mark Billinghurst <grof@h ..................> | Received: | Nov 1, 2003 |

To | <artoolkit@h ..................> | ||

Subject: | Re: Again: about using multiple markers for tracking | ||

Hi, the simple example is already given in the ARToolKit example. Ok, lets have a more detailed look at the marker.dat file. It describes a set of markers plus a offset transformation for each marker. This offset transformation is applied to the transformation matrix of the detected marker. The result is a referenze coordinate system for all these markers. This means if we detect one of the defined markers then we always get this coordinate system. If we want to define a new multi marker then we have to define this reference coordinate system. In marker.dat the marker Data/multi/patt.a is such a reference coordinate system, because the transformation is the identity matrix. If we take a closer look at the other markers we will see that: * Data/multi/patt.b is translated 100 along the x-axis * Data/multi/patt.c is translated 200 along the x-axis * Data/multi/patt.d is translated -100 along the y-axis * Data/multi/patt.g is translated -100 along the y-axis and 100 along the x-axis * Data/multi/patt.f is translated -100 along the y-axis and 200 along the x-axis So, all these markers are placed by the given offset transformations. For the MR assembly instructor (presented at ISMAR03) we use a similar approach and we automatically calibrate these transformations. Just by detecting one of the already defined markers and calculating the tranformation between the reference system and the new marker. I hope my explanation helps a little bit. Best regards, Juergen Zauner ============================================ Upper Austria University of Applied Sciences Department of Mediatechnologies and -design Hauptstraße 117 A-4232 Hagenberg AUSTRIA |