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At what distance from you can you fly without losing VLOS?
2841 27 2019-8-25
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nilanjan118
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UAV laws from almost every country mandate that the drone should be within VLOS (visual line of sight) from the pilot all the time. Now considering the size of the Spark and without using any external accessories/aid to improve visibility (strobe lights on the Spark, having a spotter nearby with binoculars etc.), at what range from you can you fly without losing VLOS at daytime assuming you have clear weather?
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33.33% (6)
50.00% (9)
0.00% (0)
16.67% (3)
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2019-8-25
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David Martin Graff
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There is a school of thought that says with a well lit drone in the night you can see a drone as far as two miles away, during the daylight that's a different story..
2019-8-25
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nilanjan118
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David Martin Graff Posted at 8-25 19:22
There is a school of thought that says with a well lit drone in the night you can see a drone as far as two miles away, during the daylight that's a different story..

That's the reason I mentioned daytime. Thanks for your thoughts.
2019-8-25
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David Martin Graff
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nilanjan118 Posted at 8-25 19:48
That's the reason I mentioned daytime. Thanks for your thoughts.

No problem my pleasure...
2019-8-25
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S-e-ven
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To find it easily, again, after looking on he screen for some seconds, it is probably more 250 then 500m
And out of experience, that is mostly just with sky behind the bird.
Flying in front of a skyline or a hillside or such, it needs mostly permanent observation, not to loose it out of sight.
But on the other hand, with white clouds in the background, there is still 750+m vlos possible.
And yes, in the dark it gets a lot easier to follow it with the eyes.

I voted 250-500m
2019-8-25
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nilanjan118
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S-e-ven Posted at 8-25 23:11
To find it easily, again, after looking on he screen for some seconds, it is probably more 250 then 500m
And out of experience, that is mostly just with sky behind the bird.
Flying in front of a skyline or a hillside or such, it needs mostly permanent observation, not to loose it out of sight.

Nicely broken down. It is true that it is not always possible to keep an eye on the bird and especially if you wish to get good footage, you will invariably look the screen every now and then to check if the framing is proper. In such scenarios, I too feel it will be easier to not lose sight at 250m~500m range.
2019-8-25
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Nidge
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This can be quite subjective as it will depend on the individual’s eyesight and the conditions (visibility due to moisture and lighting). I would say for someone with healthy eyes a realistic distance for the Spark would be a few hundred feet to be able to not just see the craft but to be able to reliably determine its attitude and true motion.

It is generally considered that with healthy 20/20 eyesight that the human eye can resolve two high contrast point sources 30cm apart at a distance of 1km. However the Spark, being only 14.5cm in length and 5.5cm in width and height, would only just be discernible at 500m and a much shorter distance would be required to actually determine its orientation and relative motion - in optimum conditions of visibility.
Regards

Nidge.
2019-8-26
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ssylca44
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250m to 300m
2019-8-26
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ssylca44
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David Martin Graff Posted at 8-25 19:22
There is a school of thought that says with a well lit drone in the night you can see a drone as far as two miles away, during the daylight that's a different story..

Quite right,  it also depends on the sun position.
2019-8-26
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DJI Stephen
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Hello and good day nilanjan118.  Thank you for reaching out and creating this poll. I hope that you will get the best answer and information and from our valued DJI co members on there insights with regards to this matter. Thank you all for your valued support.
2019-8-26
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Tentoes
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Not near as far as when I was younger!
2019-8-26
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LouisP
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It depends on the sky... on a clear sunny day I struggle to see it 100 meters away... but on a cloudy day I have been able to see it 350 meters away.
2019-8-26
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nilanjan118
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Nidge Posted at 8-26 00:29
This can be quite subjective as it will depend on the individual’s eyesight and the conditions (visibility due to moisture and lighting). I would say for someone with healthy eyes a realistic distance for the Spark would be a few hundred feet to be able to not just see the craft but to be able to reliably determine its attitude and true motion.

It is generally considered that with healthy 20/20 eyesight that the human eye can resolve two high contrast point sources 30cm apart at a distance of 1km. However the Spark, being only 14.5cm in length and 5.5cm in width and height, would only just be discernible at 500m and a much shorter distance would be required to actually determine its orientation and relative motion - in optimum conditions of visibility.

Thank you for this wonderful insight.
Yes, VLOS is totally a subjective thing and that's why I created this poll to understand what others felt about it. There is no right or wrong answer here.
2019-8-26
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Nidge
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nilanjan118 Posted at 8-26 15:35
Thank you for this wonderful insight.
Yes, VLOS is totally a subjective thing and that's why I created this poll to understand what others felt about it. There is no right or wrong answer here.

My pleasure.

If you really want to geek out on the science behind this, or need something to help you sleep as it’s not particularly sexy, you can look into the Rayleigh Criterium, a mathematical theory that determines resolution based on distance and aperture. Personally I don’t get out much and my only friends are my collection of singing potatoes.

Regards

Nidge.

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/Raylei.html
2019-8-27
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DAFlys
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VLOS is as much about seeing whats around the drone as the drone itself, so adding strobes etc does not increase VLOS.  
2019-8-27
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nilanjan118
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DAFlys Posted at 8-27 04:17
VLOS is as much about seeing whats around the drone as the drone itself, so adding strobes etc does not increase VLOS.

Not sure this is true. How are people flying in the night then?
2019-8-29
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S-e-ven
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Nidge Posted at 8-27 01:17
My pleasure.

If you really want to geek out on the science behind this, or need something to help you sleep as it’s not particularly sexy, you can look into the Rayleigh Criterium, a mathematical theory that determines resolution based on distance and aperture. Personally I don’t get out much and my only friends are my collection of singing potatoes.

Mmmh, I thought that the Rayleigh Criterion is not for eyesight, but  for optical instruments.
May have to recheck on this.

Also a flasher with a creed may not increase the vlos, but the visibility of a flasher in the vlos.
You dont see the drone better, but you'll see the flasher.
Which means that you'll see the drone, since the flasher is connected to it.
"To see or not to see, that's the question" if I may say it this way ;-)
2019-8-29
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DAFlys
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nilanjan118 Posted at 8-29 18:22
Not sure this is true. How are people flying in the night then?

I think it depends on which country your thinking about.  Night flying in some countries is banned and the VLOS rules seem slightly different too.
2019-8-30
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Nidge
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S-e-ven Posted at 8-29 19:00
Mmmh, I thought that the Rayleigh Criterion is not for eyesight, but  for optical instruments.
May have to recheck on this.

The human eye can be considered an optical instrument, albeit a poor one which relies on the processing power of the brain to form a coherent image.
The description below is taken. from wikilectures.eu

Regards

Nidge.




The Angular Resolution of Human Eye

The angular resolution or spatial resolution of an optical system can be estimated by Rayleigh's Criterion.
When two point sources are resolved from each other, they are separated by at least the radius of the airy disk. When Θ = 1.22 (λ/D) rad ,
where Θ is the angular resolution, λ is the wavelength of light and D is the diameter of the eye. Remember that 360 degrees = 2π radians.
The eye pupil diameter changes during day and night, whereas the day the pupil size is between 3 mm to 4 mm and at night it is from 5 mm to 9 mm. In addition, the optimal sensitivity of the human eye is approximately 0.55 μm (V-band). So according to Rayleigh's Criterion, we can calculate the spatial resolution of human eye. Lets say that at day time the pupil size is 3 mm and the optimal sensitivity is 0.55 μm, we can apply the rule.
Θ = 1.22(λ/D)rad

=1.22(0.55 μm/3 mm)rad(180 deg/π rad)(1 mm/103 μm)

= 0.0128 deg(3600”/1 deg)

= 50” (day)
Moreover, at night the pupil diameter increases to 9 mm to increase the observation, we can do the same calculation to find the angular resolution of the eye at night.
2019-8-30
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Tentoes
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I had Phoebe out 700 ft the other day without incident. Let's see.. 213 meters. Or is that metres?
2019-8-30
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S-e-ven
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Tentoes Posted at 8-30 04:56
I had Phoebe out 700 ft the other day without incident. Let's see.. 213 meters. Or is that metres?

You are in the US, so meter it is ;-)
2019-8-30
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Tentoes
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S-e-ven Posted at 8-30 05:26
You are in the US, so meter it is ;-)

I'm in US, so FEET it is

But mine are only 9 inches long, not 12.
2019-8-30
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S-e-ven
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Tentoes Posted at 8-30 06:48
I'm in US, so FEET it is[view_image]

But mine are only 9 inches long, not 12.

Both!

https://en.wikipedia.org/wiki/Metre

2019-8-30
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H. Arif - Nobody
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its all about weather conditions. voted less than 250 based on poor eyesight.
2019-8-30
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Tentoes
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Was out 1735 ft today. Blinked and lost track of the dot. I could see there was absolutely nothing around her.
2019-8-31
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Xiarcher
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David Martin Graff Posted at 2019-8-25 19:22
There is a school of thought that says with a well lit drone in the night you can see a drone as far as two miles away, during the daylight that's a different story..

So as a new flyer my question would be seeing the drone at night with lights. are you seeing the drone or the lights? Is this an issue in the VLOS law or is this OK? I'm 65 yrs old and run lights to lets say keep me honest while flying, I can see my Mini 2 to 300m no issues but could go just a bit further by the aid of the lights. Is this OK to do? At 300m I can take my eyes off and go back no problem but at 350m i need the aid of the lights. This is all daytime flying. Any help would be great.
2021-12-15
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David Martin Graff
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Xiarcher Posted at 2021-12-15 06:50
So as a new flyer my question would be seeing the drone at night with lights. are you seeing the drone or the lights? Is this an issue in the VLOS law or is this OK? I'm 65 yrs old and run lights to lets say keep me honest while flying, I can see my Mini 2 to 300m no issues but could go just a bit further by the aid of the lights. Is this OK to do? At 300m I can take my eyes off and go back no problem but at 350m i need the aid of the lights. This is all daytime flying. Any help would be great.

I personally don't fly past sunset, but I think the more you can see the drone if that means adding visual assisted accessories to brighten and help make the drone identifiable in a dark sky, then that would not alone permit the drone to be compliant with the guidelines when flying your drone at night.
3-22 21:17
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Wolferl
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David Martin Graff Posted at 3-22 21:17
I personally don't fly past sunset, but I think the more you can see the drone if that means adding visual assisted accessories to brighten and help make the drone identifiable in a dark sky, then that would permit the drone to be compliant with the guidelines when flying your drone at night.

Not really. VLOS means not only "seeing" (spotting) your drone, but being able to judge the bird's attitude! Visual aids don't help much on small birds like the Spark.

Cheers,
Wolferl
3-23 02:09
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