ACTUAL AGL readings?

Geramy · Jun 10, 2017

In this day and age... Is there an app or a setting for DJI GO or Litchi that will give you live feedback of your ACTUAL height above the ground? With maps like Google or so.ilar, this shouldn't be difficult at all, bit the only feedback I see is the AGL from the home point. How can we see the actual AGL as we fly over uneven terrain?

Meta4 · Jun 10, 2017

Geramy said:
In this day and age... Is there an app or a setting for DJI GO or Litchi that will give you live feedback of your ACTUAL height above the ground?
... but the only feedback I see is the AGL from the home point. How can we see the actual AGL as we fly over uneven terrain?

No
You have to manage that yourself just like the pilot of a Cessna does.

Geramy said:
With maps like Google or similar, this shouldn't be difficult at all,

Even if that could be done it would be of very limited value.
The heights shown in mapping do not include the heights of trees and other obstacles.

msinger · Jun 10, 2017

Geramy said:
With maps like Google or so.ilar, this shouldn't be difficult at all, bit the only feedback I see is the AGL from the home point

While this would be technically possible, I don't know if it would be a better than what we have now. Some areas in Google Maps do not include elevation data and others are outdated (some trees grow fast!). It would be neat to have this number displayed in DJI GO beside the existing altitude value. I doubt we'll see it anytime soon though since there are probably costs involved to get this data from Google (or to even use their maps in DJI GO).

Richard R · Jun 10, 2017

The only practical approach would be with a laser altimeter. A small system with 3-400 m range shouldn't cost the manufacturer more than 50-75$ ( which means it would probably cost the consumer $150-200!). Wouldn't need any external maps and could account for trees, structures, etc. would there be issues? Yes, but totally workable. I'd replace the VPS module and include it in the data stream back to the RC.

HWCM · Jun 11, 2017

msinger said:
While this would be technically possible, I don't know if it would be a better than what we have now. Some areas in Google Maps do not include elevation data and others are outdated (some trees grow fast!). It would be neat to have this number displayed in DJI GO beside the existing altitude value. I doubt we'll see it anytime soon though since there are probably costs involved to get this data from Google (or to even use their maps in DJI GO).

So in google maps, the altitude shown, is that ground floor height or tree top estimated height? If I am looking at Goggle maps of a dense forest, is the altitude shown ground floor? Or tree top? I have often wondered this for waypoint missions.

Richard R · Jun 11, 2017

Pretty sure that they are ground or 'rare earth' values, but in wooded areas they are going to be estimates. Even tree height measurements can be off significantly as some trees can grow several feet in a year! Give yourself plenty of margin

Meta4 · Jun 11, 2017

HWCM said:
So in google maps, the altitude shown, is that ground floor height or tree top estimated height? If I am looking at Goggle maps of a dense forest, is the altitude shown ground floor? Or tree top? I have often wondered this for waypoint missions.

Terrain height in Google Earth and any maps is ground level and does not account for trees, buildings and other obstacles.

msinger · Jun 11, 2017

HWCM said:
So in google maps, the altitude shown, is that ground floor height or tree top estimated height? If I am looking at Goggle maps of a dense forest, is the altitude shown ground floor? Or tree top? I have often wondered this for waypoint missions.

You can find the elevation of the ground, buildings, trees, etc. in Google Maps. For example, here are two elevations (circled in red) of the street and a nearby building:

By subtracting those elevations, I can estimate that building is about 125 feet high.

Loz · Jun 14, 2017

msinger said:
You can find the elevation of the ground, buildings, trees, etc. in Google Maps. For example, here are two elevations (circled in red) of the street and a nearby building:

By subtracting those elevations, I can estimate that building is about 125 feet high.

Hi how did you enable that capability in google maps please? I tried to find it in Google Maps app on my iPad Pro and in Google Earth (your pics show Google Earth) without success - perhaps I need to go to my desk PC & try...

With The Birds · Jun 14, 2017

Loz said:
Hi how did you enable that capability in google maps please? I tried to find it in Google Maps app on my iPad Pro and in Google Earth (your pics show Google Earth) without success - perhaps I need to go to my desk PC & try...

That will do it.