Hi,

Francois LE COAT writes:
>> Monocular Depth:
>>
>> <https://www.youtube.com/watch?v=34zUDqEzHos>
>>
>> A drone flies between the trees of a forest. Thanks to the optical-flo
w
>> measured on successive images, the temporal disparity reveals the
>> forest of trees... We take a reference image, the optical-flow is
>> measured on two rectified images. Then we change the reference when
>> the inter-correlation drops below 60%. We can perceive the relief in
>> depth with a single camera, over time.
>>
>> In fact, when we watch images captured by a drone, although there is
>> only one camera, we often see the relief. This is particularly marked
>> for trees in a forest. The goal here is to evaluate this relief, with 
a
>> measurement of "optical-flow", which allows one image to be matched wi
th
>> another, when they seem to be close (we say they are "correlated").
>>
>> We have two eyes, and the methods for measuring visible relief by 
>> stereoscopy are very developed. Since the beginning of photography,
>> there were devices like the “stereoscope” which allows
 you to see the
>> relief with two pictures, naturally. It is possible to measure relief,

>> thanks to epipolar geometry, and well-known mathematics. There are man
y
>> measurement methods, very effective and based on human vision.
>>
>> When it comes to measuring relief with a single camera, knowledge is
>> less established. There are 3D cameras, called "RGBD" with a "D" for 
>> "depth". But how do they work? Is it possible to improve those? What
>> I am showing here does not require the use of any “artificial 
neural
>> network”. It is a physical measurement, with a classic algorit
hm,
>> which does not come from A.I. nor a big computer :-)
> 
> A WEB page was made to illustrate Monocular Depth...
> 
> <https://hebergement.universite-paris-saclay.fr/lecoat/demoweb/monocula
r_depth.html> 
> 
> 
> This is about measuring monocular depth, just as stereoscopic disparity

> is measured. It means quantifying the depth, with images from a single
> camera. We can see this relief naturally, but it is a matter of
> measuring it with the optical-flow :-)

Until now, drone images came from forests in France. The first images
were obtained in the French Vosges.

<https://www.youtube.com/watch?v=245yJJrwMQ0> Drone in the forest

We are now seeing more and more drones in forests outside of France.
The available image sources are diversifying...

Best regards,

-- 
François LE COAT
<https://eureka.atari.org/>

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