WKM waypoint HEIGHT OFFSET

[Naughty dog]

I would just like some info please for the height offsetting function.

Do you just except what the ground station suggests, and do you change it in height or elevation mode?

I am about to take it on its maiden GPS flight, but struggle to understand the chinglish instructions.

Offset says...
Last offset. 53
current offset. 53
recomend 59
set off set as 59

so I just click ok and set my way points ?

any advice before it gets dark today would be gratefully received.

naughty dog

 

[Kentjjl]

I just except what ground station suggests.

 

[Naughty dog]

I just except what ground station suggests.

Cheers buddy

just had two successful flights, after a day of simulation. Very impressed.

It didn't take off for the first flight ( even the motors didnt start) then I did the exact same things again, and it went perfectly.

Then repeated the first flight, and auto landed both flights.

click and go tomorrow..

 

[gtranquilla]

Sounds very encouraging...... I hope to be doing the same in a few days or weeks...... Seems to me I read from someone with experience with GCS that one should avoid the click and go mode or was it auto takeoff or one could be into the trees in no time......
seems to me one needs a 3D home point and go to point that is defined in advance well above surface grade level.

Cheers buddy

just had two successful flights, after a day of simulation. Very impressed.

It didn't take off for the first flight ( even the motors didnt start) then I did the exact same things again, and it went perfectly.

Then repeated the first flight, and auto landed both flights.

click and go tomorrow..

 

[hover.ch]

I always use altidude offset without thinking/changing anything, selecting height mode. It works pretty well, however, there is some magic going on.

I still haven't understood why GS is relying on altitude (above sea level) at all. If I understand WKM and GS right, the height is determined by a pressure sensor which needs to be nulled before takeoff. This is done via "Altidude Offset", if I'm right. At that time, all the WP's height is also recalculated, but why all that complexity. Who really wants to define a mission with absolute altitude (above sea level) at all. Anyone amongst you?

It really gets odd when setting WPs above water (lake, river), see note in GS manual. As I said, why do they (DJI) use absolute altitude at all?
But maybe I'm missing the point.

 

[FerdinandK]

You can either choose absolute altitude or relative to the starting point (which I prefer).

best regards
Ferdinand

 

[gtranquilla]

I have always assumed that the altitude offset has nothing to do with actual flying..... only the virtual appearance of the MR within GCS Google Earth Overlay! Hope this assumption is correct..... can somewhere confirm or clarify this before I start flying with GCS?

I always use altidude offset without thinking/changing anything, selecting height mode. It works pretty well, however, there is some magic going on.

I still haven't understood why GS is relying on altitude (above sea level) at all. If I understand WKM and GS right, the height is determined by a pressure sensor which needs to be nulled before takeoff. This is done via "Altidude Offset", if I'm right. At that time, all the WP's height is also recalculated, but why all that complexity. Who really wants to define a mission with absolute altitude (above sea level) at all. Anyone amongst you?

It really gets odd when setting WPs above water (lake, river), see note in GS manual. As I said, why do they (DJI) use absolute altitude at all?
But maybe I'm missing the point.

 

[hover.ch]

I have always assumed that the altitude offset has nothing to do with actual flying..... only the virtual appearance of the MR within GCS Google Earth Overlay! Hope this assumption is correct..... can somewhere confirm or clarify this before I start flying with GCS?

I think you are right, in general. However, when I define a waypoint with an altitude of let's say 20m, do an altitude offset while my MR is on the ground and upload the mission, I see that the altitude uploaded is somehow "corrected" by a small amount, usually a fraction of a meter. The altitudes uploaded are never rounded numbers. This might have to do with small altitude drifts occuring between altitude offset (calibration) and upload time, I don't know. I have to take a closer look at my screen recordings.

 

[hover.ch]

I just come back from the flying field and once again I observed that a WPs height (e.g. 40m) has been changed after setting (the proposed) altitude offset. When I uploaded the 1 WP mission GS changed the WP's height by about 5m! Why? I didn't change location and of course I didn't change the altitude in between.

I can imagine that absolute altitude can make sense (e.g. in a mission file), such that the same mission can be flown from different launch altitudes. Barometric height is not absolute and not precise over time, so "altitude offset" sets it (relative height) to 0, wherever the MR is. Right? But still, why does GS compensate my height while I'm not moving, within a few minutes when even barometric pressure doesn't change dramatically...?

 

[iflynavy]

I'm not sure I feel much better then reading the manual here

I'd love to take mine over water but the damn note in the manual scares me. Any chance one of you has done that and can explain that to me?

For instance if I'm flying over a lake with an unknown depth and have the way point altitude of 50M, will it go lower while over the lake because the WKM considers the relative height from the bottom?

 

[Pheliciano]

Before anything else, I'd better say that I've not flown any GS missions yet, I'm just trying to get to grips with it and like a lot of other people it seems, the ambiguity in the manual makes me nervous.

From the Manual, it seems that the altitude offset value is only used in the on-screen visualisation and not in the actual altitude of the mission. Does anyone know if the same is also true of the height/elevation mode? does this only affect the visuals on screen?

Also, does above ground level mean relative to the ground height as it appears on Google Earth, or above the take-off point? For example, if I takeoff from somewhere that is 50m above sea level (AMSL) and set a waypoint at a value of 50m over a hilltop that is at 150m AMSL, will my S800 try to fly to an altitude of 100m AMSL or 200m AMSL?

I can see why being able to work at an altitude above sea level would be useful: for flying a survey / photogrammetry mission where you want to fly at a level altitude for the entire flight regardless of terrain change underneath. Plus, being a (somewhat) absolute value, altitudes AMSL are much less confusing...