Hi,
Is it possible to use several single marker with
“TrackerSingleMarkerImpl” ?
many thanks




	

	
		
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Andriamasinoro Rahajaniaina wrote:
> Is it possible to use several single marker with
> “TrackerSingleMarkerImpl� ?
>   
Short answer yes.

Long answer:
How easy it is depends on if you want to track more than one marker in
the same image or not. TrackerSingleMarker is optimized for an easy API
usage. Calling calc() will return the id of the best detected marker.
You can then call getARMatrix() to get the pose of that marker. This
will always only return the best marker in the image.
If you want to track all markers in the image then you'll have to use
the more general Tracker API, which is more or less identical (with many
extensions) to that of ARToolKit.

I know that this is not ideal and we'll probably add a new, more
powerful interface in the future that unites single- and multi-marker
tracking with all those features people usually require and the easiness
of the current APIs.

Daniel

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You can also have multiple trackers. But because it returns the best
id-image, you can use your own markers instead of id-markers. You lose
efficiency and depending on the complexity of your system, this might really
slow down your system. But if you have only 2 or 3 single markers, you
should be able to do so before future API comes about. You can still use
id-markers for 2 of those trackers, ie. simple and bch markers.


On 1/27/07, Daniel Wagner <daniel@i ...............> wrote:
>
> Andriamasinoro Rahajaniaina wrote:
> > Is it possible to use several single marker with
> > "TrackerSingleMarkerImpl" ?
> >
> Short answer yes.
>
> Long answer:
> How easy it is depends on if you want to track more than one marker in
> the same image or not. TrackerSingleMarker is optimized for an easy API
> usage. Calling calc() will return the id of the best detected marker.
> You can then call getARMatrix() to get the pose of that marker. This
> will always only return the best marker in the image.
> If you want to track all markers in the image then you'll have to use
> the more general Tracker API, which is more or less identical (with many
> extensions) to that of ARToolKit.
>
> I know that this is not ideal and we'll probably add a new, more
> powerful interface in the future that unites single- and multi-marker
> tracking with all those features people usually require and the easiness
> of the current APIs.
>
> Daniel
>
>

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You can also have multiple trackers. But because it returns the best id-image, you can use your own markers instead of id-markers. You lose efficiency and depending on the complexity of your system, this might really slow down your system. But if you have only 2 or 3 single markers, you should be able to do so before future API comes about. You can still use id-markers for 2 of those trackers, ie. simple and bch markers.
<br><br><br><div><span class="gmail_quote">On 1/27/07, <b class="gmail_sendername">Daniel Wagner</b> &lt;<a href="mailto:daniel@i ...............">daniel@i ...............</a>&gt; wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Andriamasinoro Rahajaniaina wrote:<br>&gt; Is it possible to use several single marker with<br>&gt; "TrackerSingleMarkerImpl" ?<br>&gt;<br>Short answer yes.<br><br>Long answer:<br>How easy it is depends on if you want to track more than one marker in
<br>the same image or not. TrackerSingleMarker is optimized for an easy API<br>usage. Calling calc() will return the id of the best detected marker.<br>You can then call getARMatrix() to get the pose of that marker. This<br>
will always only return the best marker in the image.<br>If you want to track all markers in the image then you&#39;ll have to use<br>the more general Tracker API, which is more or less identical (with many<br>extensions) to that of ARToolKit.
<br><br>I know that this is not ideal and we&#39;ll probably add a new, more<br>powerful interface in the future that unites single- and multi-marker<br>tracking with all those features people usually require and the easiness
<br>of the current APIs.<br><br>Daniel<br><br></blockquote></div><br>

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Hi,
I've been able to successfully track multiple markers with a single call =
to
the TrackerSingleMarker calc() method.
The key idea is to get access to the low-level marker data by using the
extra parameters in calc and making sure you allocate enough memory for =
all
the markers with Init. You then process the marker data manually to =
extract
out the markers.
I think this is better than multiple calls to calc with different =
pattern
numbers because you avoid processing the image multiple times. In the =
code
below, m_Tracker is of type ARToolKitPlus::TrackerSingleMarker. The stl =
list
m_MarkerData collects data on each marker, including a flag to hide or =
show
it.  Notice I also chose to set the updatematrix flag in calc to false =
to
avoid recomputing it twice since I do it manually with
calcOpenGLMatrixFromMarker. Hope this helps!

Vic
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

	// New general multiple marker tracker code. Avoids processing video
frame multiple times
	ARToolKitPlus::ARMarkerInfo *markerinfo;
	int nummarkers;

	// Do not calculate opengl matrix (set nUpdateMatrix to false) since
we'll do it ourselves
	m_Tracker->calc(data,-1,false,&markerinfo,&nummarkers);

	int size =3D m_MarkerData.size();
	for (int c =3D 0; c < size; c++) {
				int k =3D -1;
				for (int m =3D 0; m < nummarkers; m++) {
					if (markerinfo[m].id =3D=3D c) {
						if (k =3D=3D -1)=20
							k =3D m;
						else if (markerinfo[k].cf <
markerinfo[m].cf)
							k =3D m;
					}
				}

				if (k =3D=3D -1) { // no marker found
					m_MarkerData[c].m_Visible =3D false;
				}
				else { // marker found
					m_MarkerData[c].m_Visible =3D true;
					m_MarkerData[c].m_Confidence =3D
markerinfo[k].cf;
					ARFloat center[2] =3D {0.0f,0.0f};
					ARFloat patttrans[3][4];
=09
m_Tracker->calcOpenGLMatrixFromMarker(&markerinfo[k],center,m_MarkerData[=
c].
m_Width,(ARFloat *)m_MarkerData[c].m_ModelViewMat);
	} // end markers

-----Original Message-----
From: owner-artoolkit@h ..................
[mailto:owner-artoolkit@h ..................] On Behalf Of Andriamasinoro
Rahajaniaina
Sent: Saturday, January 27, 2007 4:40 AM
To: artoolkit@h ..................
Subject: using TrackerSingleMarkerImpl


Hi,
Is it possible to use several single marker with =
=93TrackerSingleMarkerImpl=94 ?
many thanks




=09

=09
	=09
_________________________________________________________________________=
__=20
D=E9couvrez une nouvelle fa=E7on d'obtenir des r=E9ponses =E0 toutes vos =
questions !

Profitez des connaissances, des opinions et des exp=E9riences des =
internautes
sur Yahoo! Questions/R=E9ponses=20
http://fr.answers.yahoo.com