Litchi Question regarding Waypoint Flying

[GP-Mavic]

I'll be flying my Mavic into a canyon from about 150 feet above the bottom. Waypoint 1 height is set at 98 feet above my take off point, and so are the rest of the waypoints. Is the 98 foot height maintained throughout the flight (98 feet above take off point) making the flight level or will it drop down to 98 feet above the canyon terrain? Do I need to adjust for any trees in the canyon? Thanks!

 

[Ed_2020]

The height will be tied to your take off point.

If I got it right, it will be 98 ft above you and 248 above the canyon bottom, since the take off was 150 above it.

Any obstacle is not considered, you need to take them into account when planning the mission.

 

[GP-Mavic]

Thanks Ed... I suspected as such but wanted confirmation. I'll do a short test run of a few points out and back. I thought about setting it up to follow the terrain but from that height I can't tell how tall the trees are, and there are just a few but mostly scrub. Thanks again.
Gary

 

[Ed_2020]

Thanks Ed... I suspected as such but wanted confirmation. I'll do a short test run of a few points out and back. I thought about setting it up to follow the terrain but from that height I can't tell how tall the trees are, and there are just a few but mostly scrub. Thanks again.
Gary

I would approach it with a 'survey' flight to measure things around, using safe margins.

After watching the video, I start trimming it down, fine tuning the mission. Litchi allows you to go down too (I've reached -54 ft).

You can check the real heights as measured by Mavic/Litchi reading the Log or SRT files (good source for new waypoints coordinates too).

SRT files can be recorded to your microSD card together with the video file, you must set Video Caption ON on Litchi settings.

In case you have only one shot to make it on location, the better you prepare, the better results will be.

For such you could start with Google Maps 3D or Google Earth.

Then you can plot the waypoints using elevation data: WP Height = Elevation MINUS TakeOff_Point_Elevation PLUS Flight_Height (100 ft?), knowing there is an error margin embedded.

Prior to mission flight, you can take a short survey flight (3 minutes?) just to measure the real Litchi height perception on location.

You just need to get close to some chosen landmark and check the Mavic height.

Take the difference to the elevation data used while planing and apply to all your waypoints (batch edit).

Go for the mission and keep your finger ready to switch to Sport Mode if something looks wrong ;-)

 

[GP-Mavic]

Excellent thought process. I'll do just that. This should be interesting. Going to fly it this weekend. Thanks again!

 

[Ed_2020]

Excellent thought process. I'll do just that. This should be interesting. Going to fly it this weekend. Thanks again!

Glad to help, nowadays the mission planning is part of the fun to me.

In case you want to be extra careful, keep the flight over the deep part, filming the walls, etc, while changing height.

Flight it first, if everything is OK, deploy the terrain following mission.

Regarding trees, with time you will train your eye to estimate them. Around where I live they are mostly 50 / 70 ft high.

Good luck, hope you have a nice flight, let me know later how it went ;-)

 

[GP-Mavic]

Hi Ed,
Well, unfortunately it didn't go as planned. As a test run I set several waypoints at the same height as the take off point (98 feet) expecting a relatively level flight out around the canyon. Once the Mavic reached the 1st waypoint it headed for the second point. (All good so far.) Upon reaching the edge of the canyon wall it took an immediate nose dive in what appeared to be an attempt to reach 98 feet above the canyon floor. In the path of the Mavic was a 125+ foot eucalyptus tree which it headed right towards. I didn't know how to cancel the mission so I tried to fly with the controller but the only thing that worked was reversing with the right stick. I brought it about half way back released the stick and it resumed going from point 1 to point 2, again headed right for the tree. Tried to exit out of Waypoint and nothing. Pulled it back again until the drone was overhead, initiated landing and all was well (except for my sweaty palms) I just read that to cancel a mission, get out of Waypoint then switch from P to S then back to P. I'll have to try that in a much safer place. Thanks again for your insight. Looks like I still have a great deal to learn.
Gary

 

[Ed_2020]

Hi Ed,
Well, unfortunately it didn't go as planned. As a test run I set several waypoints at the same height as the take off point (98 feet) expecting a relatively level flight out around the canyon. Once the Mavic reached the 1st waypoint it headed for the second point. (All good so far.) Upon reaching the edge of the canyon wall it took an immediate nose dive in what appeared to be an attempt to reach 98 feet above the canyon floor. In the path of the Mavic was a 125+ foot eucalyptus tree which it headed right towards. I didn't know how to cancel the mission so I tried to fly with the controller but the only thing that worked was reversing with the right stick. I brought it about half way back released the stick and it resumed going from point 1 to point 2, again headed right for the tree. Tried to exit out of Waypoint and nothing. Pulled it back again until the drone was overhead, initiated landing and all was well (except for my sweaty palms) I just read that to cancel a mission, get out of Waypoint then switch from P to S then back to P. I'll have to try that in a much safer place. Thanks again for your insight. Looks like I still have a great deal to learn.
Gary

Hi Gary,

I'm sorry to learn about that, specially as I was trying to help you get some good results.

But maybe a few lines from far away are not really enough..

I don't understand the nosedive you described, shouldn't happen between waypoints with the same height.

Regarding the emergency procedure, you can read one of my previous posts I warned you should keep your finger ready to change to Sport Mode in case thigs looked wrong.

At least you were able to recover and land, good reaction under stress anyway.

Since your initial question was about canyon flight, I didn't had much idea about your flight experience.

For sure you should train on easier scenarios. You can even have a copy of your canyon flight resized and deployed over an open field, for example.

Whenever you feel I could be of any help, don't hesitate to contact me.

Ed