Really daft question re: Height setting for Return to Home

[Cupidstunt]

Im just after a little clarification here....when we set the height to be returned at for the Return to Home function, this is the height above the take off site altitude..is this correct? Im assuming its not the height above sea level? The reason i ask is a i live on the coast at sea level and will heading up into the mountains next week and want to sure i dont set the height to tell the Mavic to crash into the side of the mountain!

 

[Big Fil]

Your correct. It's the height above your takeoff point.

 

[Cyberpower678]

It's the altitude AGL at takeoff point.

 

[Cupidstunt]

Thanks folks, that what i thought...didn't want to get it wrong though.. ;-)

 

[RavenStorm]

So wondering another question regarding this from the OP .. Lets say I set my RTH height at 100ft , I am at 200ft and for some reason I have to hit RTH,, does the Mavic climb another 100ft or does it stay at 200ft and begin its return home?

 

[Cyberpower678]

So wondering another question regarding this from the OP .. Lets say I set my RTH height at 100ft , I am at 200ft and for some reason I have to hit RTH,, does the Mavic climb another 100ft or does it stay at 200ft and begin its return home?

It stays at 200 ft.

 

[Sigh]

So it doesn't lower to the set height then come home? I was worried about that...

 

[Cyberpower678]

Nope. RTH altitude is the minimum height the drone is required to be at to fly home as set by the user. If it's already above it, it will stay at that altitude. If it's below it, it will climb to that altitude before heading home.

So it doesn't lower to the set height then come home? I was worried about that...

 

[BorisTheSpider]

It would help if DJI would use, and people understood, the terms properly. Altitude is always above sea level, height is above ground.

The advice you've been given is correct - RTH height is above the takeoff point, and the drone will not decend to that height, only climb.

 

[BorisTheSpider]

Incidentally, and I'm sure other people have thought the same, the sooner we get a global terrain model in the firmware so that RTH height, or indeed height above ground generally, can be referenced to the actual ground, the better. It would be pretty easy given that basic data to set an RTH height that would clear nearby obstacles consistently, plus it would mean the height limits in the firmware could be referenced to ground so as to be meaningful and not prevent flying up hills.

 

[HFMan]

That would require FAR more memory than is remotely possible on the Mavic. Given the potential range of a mavic, the dataset to even do a super course rendering of terrain would be very large.

 

[BorisTheSpider]

That would require FAR more memory than is remotely possible on the Mavic. Given the potential range of a mavic, the dataset to even do a super course rendering of terrain would be very large.

I don't doubt it won't happen on existing hardware, but I'm hoping in won't be too long - a high resolution terrain mesh of the entire world, such as those available for flight simulators, only requires a few tens of GB of storage which is very cheap these days.

 

[bdrowe]

does the rth still use the obstacle avoidance system

 

[BorisTheSpider]

does the rth still use the obstacle avoidance system

If you leave that option switched on. You should switch it off at least sometimes though as it can get confused by the sun low in the sky which could cause a failed RTH.

 

[Malavic]

I don't doubt it won't happen on existing hardware, but I'm hoping in won't be too long - a high resolution terrain mesh of the entire world, such as those available for flight simulators, only requires a few tens of GB of storage which is very cheap these days.

Old GPS receivers required that you pre-load the area you were planning on hiking in and you could do terrain maps. The same occurred when the first GPS for cars were out. There is no reason something like this couldn't be done. That said, for $100 and a few grams of weight, you could slap a couple hundred GBs of storage on the drone. That's enough for some pretty detailed terrain maps.

 

[Cyberpower678]

I don't doubt it won't happen on existing hardware, but I'm hoping in won't be too long - a high resolution terrain mesh of the entire world, such as those available for flight simulators, only requires a few tens of GB of storage which is very cheap these days.

Cheap to store, yes, but expensive to load.

 

[Malavic]

Cheap to store, yes, but expensive to load.

You mean to license or to use energy and cpus to process?

 

[Cyberpower678]

You mean to license or to use energy and cpus to process?

I mean to load into active memory. You realize how long one would sit there and wait for the Mavic to start up, as the terrain data gets loaded into active memory.

 

[Malavic]

I mean to load into active memory. You realize how long one would sit there and wait for the Mavic to start up, as the terrain data gets loaded into active memory.

Oh, that's trivial. You only load as you go. Once you have Sats, you load in the local quadrant and the adjacent ones. If you've ever used WAZE and a route and zoomed out, you'll see the same effect. It only loads the maps adjacent to your route and as you go, if you zoom out it'll grab them but otherwise they stay off the app. It does this to save mobile bandwidth, but in our case we'd do it to prevent long load times. Slinging gigabytes that are permanently stored in fast nvram on a fast bus is very fast.

 

[Cyberpower678]

Oh, that's trivial. You only load as you go. Once you have Sats, you load in the local quadrant and the adjacent ones. If you've ever used WAZE and a route and zoomed out, you'll see the same effect. It only loads the maps adjacent to your route and as you go, if you zoom out it'll grab them but otherwise they stay off the app. It does this to save mobile bandwidth, but in our case we'd do it to prevent long load times. Slinging gigabytes that are permanently stored in fast nvram on a fast bus is very fast.

True, it would need careful implementation though.