True AGL , (Above Ground Level)

[G Lee]

Does anyone know how to get trueAGL out of the DJI Go app or Litchi. I've tried Hivemapper and it's too limited. So far as terrain I live in a halfpipe so I never have true AGL except for home position. Any help is appreciated

 

[Fly Dawg]

You will never get "True" AGL out of a barometric altimeter.

 

[G Lee]

I guess I'll attach a small deep sea fish finder and just use that

 

[G Lee]

Thx

 

[Fly Dawg]

I guess I'll attach a small deep sea fish finder and just use that

LOL....Didn't mean to be so blunt, but it is what it is.

 

[G Lee]

Not mad just flusterd. Thx again

 

[BigAl07]

You've got to remember we're working with hobby grade components with size, weight, cost, and other performance limitations.

 

[G Lee]

Yes sir

 

[Meta4]

I guess I'll attach a small deep sea fish finder and just use that

That's probably not going to work.
To get your height above ground you'd have to do some mental arithmetic just like the pilots of small planes do.
If you owned a Cessna and wanted a radar altimeter to give you your AGL height, here's one of the smallest and cheapest ($6300 + the display unit)
It weighs more than your Phantom does.
GRA™ 55

Why do you want your AGL height anyway?

 

[G Lee]

Trying to fly by the rules. And it would be nice to know when im comming up to hills or a structure. I mentioned hivemapper earlier it does okay but is limited

 

[G Lee]

Thx for all the feedback. Just trying to learn all I can about flying a Phantom

 

[G Lee]

just wanted to pass this on so you can see it

 

[sar104]

There are two quite different approaches here that the discussion has not really differentiated, and I'm not completely clear which one you are asking about.

1. Direct measurement of altitude AGL, using a radar altimeter.
2. Calculation of altitude AGL by combining barometric altitude above takeoff point with a digital elevation model of the surrounding terrain.

(1) is not going to be possible on a consumer UAV due to weight and cost issues.

(2) is possible, even on the fly with an internet connection, but for reasonable resolution during offline flights the DEM is going to need to be downloaded and stored for specific flight areas - a high-resolution global DEM is much too large. I'm not aware that any of the flight control apps currently support this functionality, but others may be able to comment more knowledgeably on that.

 

[G Lee]

Thx sar104 for reply still processing the feedback and enjoying it