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How well can sensing system see?
1847 17 2016-3-22
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tpallai
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I know that it can see 500 pixels minimum, but I can't really get an idea of how well it is based off just number. Like for example, how well can it direct branches? Thanks
2016-3-22
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Michael M
First Officer
Flight distance : 1984898 ft
Canada
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hmm, good question.  probably not branches unless it's in directly in front of it.
2016-3-22
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Geebax
Captain
Australia
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It really cannot sense branches unless they are really thick, substantial branches. And I am pretty sure it is not limited to 500 pixels, the figure I thought I saw was 50 pixels.
2016-3-22
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Nink
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Are there any details specifications available for the optical sensing system. I assume this is some form of speckled laser analyses with an infrared grid projected at a resolution of X * Y pixels that is then read by the optical sensors and the gap between the pixels is then triangulated and a calculation is made based on the distance of the dots apart from each other  to ascertain what the object in front of it is.  I assume if it is 500 pixels (where did this info come from)  it is probably something like a 5 * 10 Matrix of pixels but do we know maximum distance that it can project the pixels with enough detail to detect the pixels.  It looks like 20 cm to 20 m sensing range but on ground it appears it sweet spot is 2 m, so I guess we could infer that it has a matrix at 2m high that it can lock onto an x * y grid with 5cm acurracy.  

There is not a lot of detail on the wiki for "Guidance"  http://wiki.dji.com/en/index.php/Guidance
Velocity Measurement Range  0~16 m/s (2m above the ground)
Velocity Measurement Accuracy 0.04 m/s (2m above the ground)
Positioning Accuracy 0.05 m (2m above the ground)
Effective Sensor Range 0.20 m ~ 20 m
External Requirements Good lighting
Texture-rich surface with clear patterns

Has anyone looked at this through an infrared camera to see the actual points projected.
2016-3-22
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Geebax
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Nink Posted at 2016-3-23 12:27
Are there any details specifications available for the optical sensing system. I assume this is som ...

Yeah, and where is the infra-red projected from?

'Has anyone looked at this through an infrared camera to see the actual points projected. '

Unless you can answer the first question, this has no bearing on the issue.
2016-3-22
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DJI-Ken
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Flyin'Bryan Posted at 2016-3-23 10:39
I haven't, but I do have infrared cameras.  Too bad I don't have a  p4.

In time my friend, I'm predicting you can't hold out for too long and you'll spring for a P4 within a month
2016-3-22
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Nink
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Geebax Posted at 2016-3-22 22:20
Yeah, and where is the infra-red projected from?

'Has anyone looked at this through an infrared c ...

EDIT: NOTE GEEBAX IS RIGHT.  This does not use IR it uses 2 * CCD to create a 3D image at 320 * 240 pixels.  My assumption of IR Speckled laser is incorrect.  This is really interesting they did not go that route like the Typhoon does.

-----------My Original Incorrect Post -----------

I was basing my assumption on the fact the previous posts discussed a perception of a pixel resolution and the fact the Typhoon H drone uses a speckled infrared laser projector with an infrared camera.  I then took into account the tear down video that appeared to show at the front of the quad a couple of CCD's but looking at the front one could be an infrared  laser projector and the other an infared camera. So I made an assumption it would be a similar system as other drones are using. The large sensors on the bottom appear they could just be using  ultransonic transmitters and receiver sensors but I don't believe that is what is used on the front as this would not provide the level of resolution  people are claiming.  A sample ultrasonic sensor would be something like this.  

http://www.gearbest.com/multi-ro ... MXdmyhhsaAlGC8P8HAQ  

You can see from these 3 images top and middle from tear down video and bottom from P4 in operation that there is two devices on left and right. I believe this is the infrared speckled or matrixed laser and infared camera you are looking for.
2016-3-22
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Geebax
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Nink Posted at 2016-3-23 14:10
I was basing my assumption on the fact the previous posts discussed a perception of a pixel resol ...

The front has two small cameras that use a 3D stereoscopic method of obstacle detection. Same with the two cameras on the bottom. The larger devices in between on the bottom are Ultrasonic transducers. The P4 uses a 3D stereoscopic method of detection, this has already been published elsewhere.
2016-3-22
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tpallai
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Nink Posted at 2016-3-22 21:27
Are there any details specifications available for the optical sensing system. I assume this is som ...

The 500 pixels is in the obstacle sensing system of the Phantom 4 User Manual
2016-3-22
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Nink
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Geebax Posted at 2016-3-23 00:05
The front has two small cameras that use a 3D stereoscopic method of obstacle detection. Same with ...

Not sure I understand.  What is the "3D Stereoscopic method of obstacle detection" it is using TOF, LIDAR or simply the fact they have to cameras focusing on the same point and triangulate the distance between the two overlapping images.  

From a VPU perspective it looks like it is using a movidius Visual Processing Unit to analyze the data for Object recognition and it also appears to do depth comprehention but I would assume it needs a depth measurement system to analyze

"Depth algorithms come in many flavors, depending on what sensors are  most appropriate for your product. If your device requires object  detection collision avoidance, or 3D reconstruction, depth extraction is  a commonly required vision algorithm. To ensure support for the  multitude of depth sensor configurations to choose from, we work with  several partners in addition to in-house teams to provide a full range  of depth solutions. Our stereo depth solution is qualified with multiple  reference sensors to support a variety of use cases."

Curious to understand how it works?

http://www.vision-systems.com/ar ... hantom-4-drone.html

http://www.movidius.com/technology
2016-3-22
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raywongmusic
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The ultrasonic sensor is on the bottom, the one on the right sends out a pulse, the one on left side pick up the echo.  The distance is determined by how much delay of echo.   You can hear ticking from the right side.
2016-3-22
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boxerman
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raywongmusic Posted at 2016-3-23 13:21
The ultrasonic sensor is on the bottom, the one on the right sends out a pulse, the one on left side ...

Why then does the VPS require adequate lighting (lux > 15)?
2016-3-22
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Ulysse
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The sonar is used to keep the vertical distance but there is also 2 cameras facing down. May be these are used to keep the horizontal position by analyzing the "colors"... being cameras, they need a minimum amount of light.
2016-3-22
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Geebax
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Ulysse Posted at 2016-3-23 17:50
The sonar is used to keep the vertical distance but there is also 2 cameras facing down. May be thes ...

Correct, the ultrasonics determine height and the cameras look for a pattern to maintain station keeping at low altitudes.
2016-3-23
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Nink
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I checked the SDK this is interesting looks like the front facing guidance is resolving a 3D Map at 320 * 240 that uses with two cameras to calculate depth.

"Depth Image: Outputs depth images for five directions. The image size is 320*240*2 bytes for each direction

https://developer.dji.com/guidance-sdk/documentation/
2016-3-23
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boxerman
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Geebax Posted at 2016-3-23 03:17
Correct, the ultrasonics determine height and the cameras look for a pattern to maintain station k ...

Well, except that its is the exact same VPS spec on the P3 series:   Surface with clear pattern and adequate lighting (Lux > 15).  And there are no optical sensors looking down on the P3s.
2016-3-23
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Geebax
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boxerman Posted at 2016-3-24 07:24
Well, except that its is the exact same VPS spec on the P3 series:   Surface with clear pattern an ...

That seems odd. There is a single optical sensor (camera) on the P3P, so I don't see why they would make different version for the Standard.
2016-3-23
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Phan-TOM
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Go in to the DJI assistant and calibrate the sensors. They are cameras, and can see pretty well, but are walleyed like one of the peep holes in a residential or hotel room door. During the calibration, you can see exactly how the imaging is.
2016-3-23
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