## Blob orientation

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BiancaSan93
Posts: 27
Joined: 25 Apr 2017, 17:26

### Blob orientation

Hi,
I am making some experiments with the blob detection camera, in order to detect the orientation of some objects in the scene, but I am unsure about the returned value.
I only have one blob and my code is

Code: Select all


res1,packet1a,packet1b=sim.handleVisionSensor(sensor1)

if res1 >=0 then

q1=packet1b[4]
q1=q1*180/math.pi --convert to degrees
sim.setFloatSignal('detectedAngle',q1)
print(q1)
end

The values printed out are obviously the angle of inclination of the detected object, but relative to what exactly? Shouldn't the orientation be a table with the euler angle, and if not, what angle is it measuring (alpha, beta, gamma)? This causes me a problem because, if I plot the results, I get the following

The object I am tracking is attached to a revolute joint, exactly in front of the sensor, following a sinusoidal trajectory.
Obviously it detects the orientation of the blob as the opposite one after certain angles. Is there a way to transform the blob orientation scalar value with respect to the orientation of another object? How do I do that, if I don't know the whole orientation matrix?

coppelia
Posts: 7680
Joined: 14 Dec 2012, 00:25

### Re: Blob orientation

Hello,

the extracted blob orientation is always relative to the vision sensor's Y axis (or its viewing axis). You can't possible extract the full orientation of the object based on a single blob, since that is 2 D information.

Cheers