Welcome Mavic Pilot!
Jump in and join our free DJI Mavic community today!
Sign up

Litchi. -200m minimum altitude at waypoints. A way to set it lower ?

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
Hi guys,
I use a Mavic Pro (FW 1.03.0400 and the modded NLD Go 4.01.22) with Litchi waypoint missions I build with VLM.
As I fly frequently in a mountainous area, I am frustrated by the -200m altitude limit under the elevation of home point. In the Litchi Hub as well as in VLM it is impossible to set altitude lower than -200m at any waypoint.
If I well understand, this limit is fixed by the DJI SDK onto which Litchi app is based.
Does somebody knows a trick to overcome it (with NLD or through an other way) ?
Thank you in advance...
 

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
If you use the "above ground level" option then that restriction goes away.
 
  • Like
Reactions: SmileyGC

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
If you use the "above ground level" option then that restriction goes away.
Thank you for answering.
I never used this option because elevations are very imprecise in my area, specially along steep slopes. Very often, I am obliged to verify with the help of topo maps and I found that Google elevations might be as wrong as +/- 100m. But I will give it a try with a large margin of error.
I hoped that it could be a line to change with the debug option of Assistant 2. If it exists, I am unable to find it and nobody seems knowing where it can be.
 
  • Like
Reactions: Former Member

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
Thank you for answering.
I never used this option because elevations are very imprecise in my area, specially along steep slopes. Very often, I am obliged to verify with the help of topo maps and I found that Google elevations might be as wrong as +/- 100m. But I will give it a try with a large margin of error.
I hoped that it could be a line to change with the debug option of Assistant 2. If it exists, I am unable to find it and nobody seems knowing where it can be.
Assistant 2 isn't going to help. This is not a firmware restriction on the aircraft - it's a limitation in the Litchi program and mission hub. The mission uploaded to the aircraft only contains waypoint altitudes relative to the takeoff point - it doesn't care if they are more than 200 m below takeoff.
 

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
Thank you again, Sar 104.
I thought that it could be an altitude limit similar to the +500m limit over takeoff imposed by DJI.
Unfortunately, it is now more difficult than some years ago to get an answer from the Litchi's support team...
 
  • Like
Reactions: Former Member

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
Thank you again, Sar 104.
I thought that it could be an altitude limit similar to the +500m limit over takeoff imposed by DJI.
Unfortunately, it is now more difficult than some years ago to get an answer from the Litchi's support team...
Bear in mind that if you set up the mission in the Litchi Mission Hub then the second number (in parenthesis) next to the waypoint is the altitude relative to the takeoff location. That's the value that you would set if you were not using the AGL option. So you can just adjust the AGL value to get the height above takeoff, just as you would if you were not in AGL mode. That way the accuracy of the DEM becomes irrelevant.
 

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
Bear in mind that if you set up the mission in the Litchi Mission Hub then the second number (in parenthesis) next to the waypoint is the altitude relative to the takeoff location. That's the value that you would set if you were not using the AGL option. So you can just adjust the AGL value to get the height above takeoff, just as you would if you were not in AGL mode. That way the accuracy of the DEM becomes irrelevant.
Yes, you're right. I will test this immediately with the mission I was planning and let you know how it works... Thanks for your help (again !)
 
  • Like
Reactions: Former Member

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
Bear in mind that if you set up the mission in the Litchi Mission Hub then the second number (in parenthesis) next to the waypoint is the altitude relative to the takeoff location. (...)
Unfortunately, in some areas of interest (for me) elevation data look as being missing in Google earth. This is the case at the remote place where I was planing my next mission and where it could be interesting to go lower than -200m under the takeoff point :
There I get this warning when I try to set waypoints AGL :

"Elevation Data Missing
Elevation Data is required to use this feature but could not be found. Import a Digital Elevation Model or enable Online Elevation in the settings."

"Online elevation" is checked in the "mission settings" window and works fine with other missions like this one :
...but not with this other one :
I'm completely puzzled because when I export as csv the mission that I am trying to build ( Mission Hub - Litchi ) I obtain a rather correct 3D representation In Google Earth and pretty good values of elevations at waypoints (see attached).
What am I missing or what Google/Litchi is doing wrong ? Any idea ?
70654
 
Last edited:
  • Like
Reactions: Former Member

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
Unfortunately, in some areas of interest (for me) elevation data look as being missing in Google earth. This is the case at the remote place where I was planing my next mission and where it could be interesting to go lower than -200m under the takeoff point :
There I get this warning when I try to set waypoints AGL :

"Elevation Data Missing
Elevation Data is required to use this feature but could not be found. Import a Digital Elevation Model or enable Online Elevation in the settings."

"Online elevation" is checked in the "mission settings" window and works fine with other missions like this one :
...but not with this other one :
I'm completely puzzled because when I export as csv the mission that I am trying to build ( Mission Hub - Litchi ) I obtain a rather correct 3D representation In Google Earth and pretty good values of elevations at waypoints (see attached).
What am I missing or what Google/Litchi is doing wrong ? Any idea ?
View attachment 70654
That's very strange - I see the same thing. If you start a mission a few miles to the east it works fine, but adding waypoints towards the location of your mission results in the no DEM message. The Litchi elevation data are supposed to be global, so that's a bug. I would report it.
 

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
That's very strange - I see the same thing. If you start a mission a few miles to the east it works fine, but adding waypoints towards the location of your mission results in the no DEM message. The Litchi elevation data are supposed to be global, so that's a bug. I would report it.
Thanks Sar104.
I have reported this issue at [email protected] yesterday night but still no answer.
This is not the only place where waypoints AGL do not work in my area. At this place, for example, it works for the mission represented at the left of the image but not for the mission at the right side although waypoint waypoint 4 of the left mission is separated from waypoint 10 of the right mission by less than 400m !
70698

It still work for the left mission if I move its waypoint 5 towards East till this postion :

70699

...but stops working if I move this waypoint further East by some tiny fraction of a degree (-1.669928 to -1.669918) :

70700

What's the hell ?
 

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
Thanks Sar104.
I have reported this issue at [email protected] yesterday night but still no answer.
This is not the only place where waypoints AGL do not work in my area. At this place, for example, it works for the mission represented at the left of the image but not for the mission at the right side although waypoint waypoint 4 of the left mission is separated from waypoint 10 of the right mission by less than 400m !
View attachment 70698

It still work for the left mission if I move its waypoint 5 towards East till this postion :

View attachment 70699

...but stops working if I move this waypoint further East by some tiny fraction of a degree (-1.669928 to -1.669918) :

View attachment 70700

What's the **** ?
There are clearly gaps in the DEM that Litchi is using. You try uploading a different DEM>

 

Peio64270

Well-Known Member
Joined
Dec 31, 2016
Messages
99
Reaction score
35
Age
73
There are clearly gaps in the DEM that Litchi is using. You try uploading a different DEM>

Sorry but I don't know what "DEM" means and consequently I don't know what is to download (and after, what do do with the dowloaded stuff and Litchi Hub) :)
 

sar104

Dic mihi solum facta, domina.
Premium Pilot
Joined
May 27, 2017
Messages
8,196
Reaction score
8,879
Location
Los Alamos, NM
Sorry but I don't know what "DEM" means and consequently I don't know what is to download (and after, what do do with the dowloaded stuff and Litchi Hub) :)
Sorry - digital elevation model. You can import your own, as mentioned in the error message:

70702

The link I provided above is one source of digital elevation models - you can download one for a specified area defined by coordinates.
 

New Threads

Forum statistics

Threads
70,481
Messages
815,922
Members
97,619
Latest member
marcio silva