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Re: Optical Inertia

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Hi,

Here is another result...

Francois LE COAT writes:
>>>> The principle of dominant 2D motion appeared at INRIA, it is here:
>>>>
>>>> <https://www.irisa.fr/vista/Themes/Logiciel/Motion-2D/Motion-2D.html>
>>>>
>>>> In our case, the dominant motion estimated from the approximation of
>>>> optical-flow (DIS - Dense Inverse Search OpenCV) is 3D and projective.
>>>>
>>>>> The experiment from Hernan Badino was redone. You can see it there...
>>>>>
>>>>>      <https://www.youtube.com/watch?v=fqWdSfN9FiA> Source
>>>>>
>>>>> The main interest is that video is looping, and the result is almost:
>>>>>
>>>>>      <https://www.youtube.com/watch?v=0ZPJmnBh03M> Reworked
>>>>>
>>>>> Well, Hernan Badino is moving his head when he is walking, so the
>>>>> reconstructed trajectory is not perfectly looping at the end. But
>>>>> we can reconstruct the movement almost perfectly. We use OpenCV
>>>>> for image processing, and POV-Ray for 3D representation. We have
>>>>> to determine projective dominant motion in the video with a
>>>>> reference image, and change it when correlation drops below 80%.
>>>>>
>>>>> We have a 3D inertial model of motion, that's why POV-Ray helps =)
>>>
>>> Three drones are flying between forests of trees. Thanks to the
>>> optical-flow (DIS OpenCV) measured on successive images, the
>>> "temporal disparity" reveals the forest of trees (3rd dimension)...
>>>
>>> <https://www.youtube.com/watch?v=QP75EeFVyOI> 1st drone
>>> <https://www.youtube.com/watch?v=fp5Z1Nu4Hko> 2nd drone
>>> <https://www.youtube.com/watch?v=fLxE8iS7fPI> 3rd drone
>>>
>>> The interest with the forest is that trajectories are curved, in
>>> order to avoid obstacles. It is measured thanks to a projective
>>> transform, and represented with <Ry,Rz,Tx,Tz> thanks to POV-Ray.
>>> The evolution of the drone is shown in front-view with its camera.
>>
>> It is possible to perceive the relief (in depth) of a scene, when we
>> have at least two different viewpoints of it. Here is a new example with
>> a drone flying in the middle of a forest of trees, and from which we
>> process the video stream from the embedded camera...
>>
>> <https://www.youtube.com/watch?v=WJ20EBM3PTc>
>>
>> When the two views of the same scene are distant in space, we speak
>> of "spatial disparity". In the present case, the two viewpoints are
>> distant in time, and we then speak of "temporal disparity". This
>> involves knowing whether the two images of the same scene are acquired
>> simultaneously, or delayed in time. We can perceive the relief in depth
>> in this case, with a single camera and its continuous video stream.
> 
> Let remind us the starting point from this thread... We've redone the
> experiment from Hernan Badino, who is walking with a camera on his head:
> 
>      <https://www.youtube.com/watch?v=GeVJMamDFXE>
> 
> Hernan determines his 2D ego-motion in the x-y plane, from corresponding
> interest points that persist in the video stream. That means he is
> calculating the projection matrix of the movement to deduce translations
> in the ground plane. With time integration, it gives him the trajectory.
> 
> We're doing almost the same, but I work with OpenCV's optical-flow, and
> not interest points. And my motion model is 3D, to obtain 8 parameters
> in rotation and translation, that I can use in Persistence Of Vision.
> 
> I'm reconstituting the 3D movement, and I discover it's giving "temporal
> disparity", that is depth from motion.

An instrumented motorcycle rolls on the track of a speed circuit. Thanks
to the approximation of optical flow (DIS - OpenCV) by the dominant
projective movement, we determine translations on the ground plane,
roll and yaw. That is to say the trajectory by projective parameters
(Tx,Tz,Ry,Rz).

<https://www.youtube.com/watch?v=-QLJ2ke9mN8>

Image data comes from the publication:

Bastien Vincke, Pauline Michel, Abdelhafid El Ouardi, Bruno Larnaudie,
Flavien Delgehier, Rabah Sadoun, Samir Bouaziz, Stéphane Espié, Sergio
Rodriguez, Abderrahmane Boubezoul. (Dec. 2024). Real Track Experiment
Dataset for Motorcycle Rider Behavior and Trajectory Reconstruction.
Data in Brief, Vol. 57, 111026.

The instrumented motorcycle makes a complete lap of the track. The
correlation threshold is set at 90% between successive images, to
reset the calculation of the projective dynamic model.

Best regards,

-- 
Dr. François LE COAT
CNRS - Paris - France
<https://hebergement.universite-paris-saclay.fr/lecoat>

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Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-02-28 14:45 +0100
  Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-03-28 16:15 +0100
    Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-04-03 18:45 +0200
      Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-10-17 15:15 +0200
        Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-10-29 19:00 +0100
          Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2024-11-21 16:35 +0100
            Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-02-24 16:30 +0100
              Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-04-01 19:15 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-05-15 15:00 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-05-30 15:51 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-06-18 15:15 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@atari.org> - 2025-09-16 15:30 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2025-10-21 16:35 +0200
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2025-11-04 16:15 +0100
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2025-11-18 15:10 +0100
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2025-12-09 15:30 +0100
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2026-01-14 15:15 +0100
                Re: Optical Inertia Francois LE COAT <lecoat@archimedium.fr> - 2026-04-28 15:45 +0200

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