Some general questions

[rophat]

Hi,

Back to the marker/tracking question:

I know it's probably OK to render the virutal object in another location rather than stick it on the marker (i.e. apply some tranformations). However, if the marker is used as a tracking reference, i mean for matching the 2D projection of the marker and the virutal object, how do you then work out the projection angle of the virtual object when it is placed at another location?

For example, if we place the marker on the wall, how do you make the virtual object stand vertically on the table rather then sticking horizontally on the marker on the wall? Of course, this is a simple case because of they are roughly right-angled, we will appreciate a more general approach.

We will definitely wriite Vizard into our budget plan if this can be solved.

Many thanks!

[farshizzo]

You can use the ARCamera.setGlobalMarker() command to use a marker as a global reference frame. For example, if you have a marker that is 300mm wide and hanging on the wall 1 meter away and 0.5 meters above the table, then you would use the following code:

import viz
viz.go()

#Add ARToolkit extension
ar = viz.add('artoolkit.dle')

#Create camera from texture
camera = ar.addWebCamera()

#Create marker from pattern file
marker = camera.addMarker('ar/patt.worldviz',width=300)

#Generate matrix of marker in global reference frame
m = viz.Matrix()
m.setPosition(0,0.5,1)
m.setEuler(0,-90,0)

#Use marker as global reference frame for camera
camera.setGlobalMarker(marker,m)

#Add object that should appear on table
viz.add('logo.ive')

If you are not using a camera parameter file that has been calibrated for your camera then the offset positions won't exactly match the physical positions. So you might need to tweak them for the object to appear at the correct location.