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Litchi App and Waypoints and Altitudes

Discussion in 'Pro/Adv Discussion' started by phelix, Apr 4, 2016.

  1. phelix

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    I am not sure if this exact question has been asked. I did a brief search and wasn't to happy with any answer that i had found. I am curious about how the altitude on the way points work. Here is what i am curious about.

    waypoint 1 = 100 feet.
    waypoint 2 = 200 feet.

    So my question is. Right at start since its waypoint one its going to go straight up 100 feet. This part I understand. So as it moves to the second waypoint will it gradually ascend as it moves to the next way point so its at 200 feet by the time it gets there? Or will it blast up to 200 feet from the first way point and travel to the second waypoint at that height. Or will it be at 100 feet and travel to second way point at 100 feet. Then once it gets to the second waypoint will it straight up to 200 feet and then move to the next point from there?? Hope this makes sense.
     
  2. jonebk12

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    The first one. The bird will gradually change altitude between waypoints. Litchi is great for very smooth, cinematic shots if you plan your missions right.
     
  3. alokbhargava

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    It would gradually move to second waypoint. I suggest if you see obstructions on the way, go to waypoint 2 height at waypoint 1 and then proceed. This way you will overcome the unexpected mistake in guesses.
     
  4. Air Ontario

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    Pretty much linear ascending between WPs in your description.
     
  5. wings1

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    Love how the bird moves between waypoints in this app. But how do you get video from the app like GO App? Is the only way to get videos that are shot during flight onto my iPhone, or do I have to get it off the SD card?
     
  6. Air Ontario

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    Can't you screen record for the lower resolution and the sd card for the higher quality?
     
  7. Erroll

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    With Litchi for iOS you can tap on the Lithci image in the top left corner and you will be presented with an option to record the screen. This doesn't only record the FPV but everything shown on the screen such as telemetry etc.
     
  8. Wolfiesden

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    The video from the camera is recorded on the SD card on the Phantom. Your android/apple device doesn't record, the phantom does.
     
  9. Erroll

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    Your device will also record FPV if you have video caching switched on.
     
  10. Wolfiesden

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    It will. However its lower resolution and lower bit rate. Its not where you want to look for quality video.
     
  11. Erroll

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    Obviously, but I did not see the word 'quality' in the question.
     
  12. Wolfiesden

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    You would if the OP started using the cached FPV video not knowing the high quality was on a uSD on the bird, probably in the form of "why is the quality so bad on my phantom?' :)
     
  13. Erroll

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    Yet you made the categorical statement "Your android/apple device doesn't record, the phantom does.".

    You would have seen the word 'skydiving' in my original post if I had included it.o_O
     
  14. Tenly

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    Back to the original question - if waypoint 1 is 100' and waypoint 2 is 200' - I get that the drone will attempt to travel in a straight line, rising gradually while it makes its way to waypoint 2...

    But the drone has a maximum vertical speed - so what happens if this distance between the 2 waypoints is too short for a smooth ascent at the requested speed? Let's say it can only rise 80' while traveling instead of the full 100'...

    What happens in that case?

    1. Before leaving Waypoint 1, the drone rises 20' straight up and then travels smoothly to Waypoint 2?

    2. The drone leaves Waypoint one and travels smoothly towards Waypoint 2 arriving at 180' and then rising the additional 20' straight up?

    3. The desired horizontal travel speed of the drone is reduced so that there is enough time to rise to the full 200' in a smooth, straight line?

    4. Something else?
     
  15. NRJ

    NRJ

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    The point that is not being mentioned here is whether you are running a mission where Litchi takes control or the user. Both are possible in various different scenario's. I you go to the flylitchi.com website, and click on help, you will learn a lot about the capabilities of Litchi. It's a great app and worth the pocket change. Don't eat out one night and it's paid for depending on where you eat.
    Litchi for DJI Phantom/Inspire
     
    Erroll likes this.
  16. Tdeath

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    From waypoint 1 to 2, the drone should ascend gradually to 200 feet at any given vertical speed ( you might see the landing gear when transitiong between waypoints if ur vertical speed is set to the max)

    Make sure your takeoff area is free from obstruction as if the mission was started before take off ( the drone will ascend gradually while going vertically at the same time)

    Imo the best practice is to start the mission while in air.
     
  17. jiggyb21

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    I asked this question months ago. I asked which had priority, speed or altitude, at a given waypoint. Someone tested it for me and I was told altitude wins....which is good news if true. I never tested it myself. Maybe you could test and report back.

    Based on what I was told, I say 4... As I understand it the aircraft slows down to be able to be at the selected altitude at each waypoint. It can, however, mess with the gimble pitch angle. I've seen some weird stuff happen. For example, the gimble planning smoothly, then jumping to meet the selected pitch at the 2nd waypoint.
     
    #17 jiggyb21, Apr 5, 2016
    Last edited: Apr 5, 2016
  18. jiggyb21

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    I just remembered I had asked the question in the closed group for Phantom Film school on Facebook. Here's a couple screenshots with the answer.
     

    Attached Files:

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  19. Mark The Droner

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    This question is simple to answer. All you need is a video of a waypoints mission with overlayed vertical speed and horizontal speed. You can see what's happening as it happens.

    I ran a mission about six weeks ago. I even saved the mission on the Litchi site. I have the overlayed video. All the details are still there.

    The first waypoint was 150 feet high and about 70 feet distance from launch. The speed was set at 4.5 mph. The second waypoint is 160 feet height and about a third mile away. Speed was set at 29 mph.

    I launched it manually so it was about ten feet high, checked that it was steady, then hit GO!

    The video shows the aircraft heading gradually to the first waypoint in an angled slope. From the video and watching on the ground, it appears to make a perfect angled flight to the first waypoint.

    However, looking at the video, the telemetry tells a slightly different story. The aircraft achieved 4.3 mph horizontal speed as it angled up to waypoint 1, then it slowed down and horizontal speed stopped, but the slow down was virtually invisible because it continued to proceed up to the correct altitude smoothly.

    Once it made altitude, the aircraft turned and proceeded to waypoint 2. This leg of the mission was almost all horizontal. But the aircraft did climb slowly and gradually for the first 500 feet horizontal distance after which it had achieved its altitude for waypoint 2. From there, it continued on until it reached waypoint 2, which telemetry shows was 1850 feet from waypoint 1. Altitude fluctuated somewhat but didn't really change after the first 500 feet horizontal distance. Aircraft achieved 27.9 mph horizontal speed and there was no discernible change in speed before or after altitude was reached.

    So in summary, in the first leg which was mostly vertical flight, the aircraft arrived at it's GPS position first even though the flight itself was mostly vertical, then rose to the prescribed altitude. The second leg which was mostly horizontal flight, the aircraft arrived at it's altitude first (about 450 feet from waypoint 1), then flew horizontal. In both cases, max speed was reached before it had maxed out on it's position or height.

    Disclaimer: I have Litchi for P2