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What is the shutter speed and ISO set by DH?

Posted: Mon Jun 11, 2018 7:15 am
by pjotrvs
What is the shutter speed set by DH when taking the images at full flight?
Does it adapt to the flight height and camera resolution?
When I set the flight speed at 8 m/s, and the shutter speed is 1/320, the drone covers 25mm in one frame. Quite a lot!
If the camera is pointed straight down, this 25mm is then also the accuracy of the captured image.
If the drone flies at 25 mm height, and the sensor resolution is 4000x3000, one pixel covers a distance of 8.75mm.
But since the distance covered in one frame is 25mm, you get a blurred image, wasting precious resolution.
To stay below the distance-per-pixel value, the shutter speed would need to be 3 times faster, so 1/1000.
With a fixed aperture, the camera would need to adjust its ISO value, also leading to a lower image quality.
It is good to realise this. Maybe DH could give a recommended max flight speed given the set height and the amount of light the sensor captures?
For sure it would be good to show the set ISO and shutter speed on the display, plus maybe the derived accuracy given the pitch angle and height.
Or did I make any mistake in these calculations?

Re: What is the shutter speed and ISO set by DH?

Posted: Mon Jun 11, 2018 12:06 pm
by Martin
Hi pjotrvs,

Forwarded the question to our dev. Will get back to you soon.


Re: What is the shutter speed and ISO set by DH?

Posted: Wed Jun 13, 2018 9:31 am
by Martin
Hi pjotrvs,

This is what our CTO told me:

We do not currently change the shutter speed when launching, it is as the user has set it, you can also adjust it at any moment during flight,
with the ability to pause the mission (you can also move the drone back / forth on the trajectory during paused state).
The recommended setup depends on the light conditions, distance to target and desired result.
For photogrammetry, a typical guideline would be to minimize the shutter speed, and try to not go below 1/320 in speed, if
its dark increase the ISO to compensate, but do not go above 400 or it will create a lot of noise. For cameras that can have aperture control,
find a middle point, completely open aperture will bring more light but result in shallow depth of field. So its a balance of all these factors.
Regarding speed of flight, this mostly depends on the distance to target, so for example if doing a mapping mission from 80 meters high a speed of 8 m/s
would be adequate for shutter speed of 1/320, if doing a site inspection flying say 10 meters from the target this would be quite bad, in this case 1-1.5 m/s is ok.