Re: [Paparazzi-devel] AGL or MSL in flight plan

On Sun, Mar 23, 2014 at 2:32 AM, Kadir ÇİMENCİ <address@hidden> wrote:

Thanks Felix, everything is clear for me now . As you said it may be better not to show AGL on dialog when SRTM data is not available..

Kadir

2014-03-22 22:01 GMT+02:00 Felix Ruess <address@hidden>:

@Chris, from my side there are currently no plans to send the very coarse SRTM data to the aircraft in order to update AGL according to location. You can have big jumps there and you shouldn't rely on it...

@Kadir, the dialog is slightly misleading... The GCS uses SRTM data to show the approximate AGL, but if you don't have SRTM data for that region it continues to show MSL as it can't compute AGL. Go to the Nav menu and enable SRTM and it will ask you to download the SRTM data, after that you should see the approximate AGL value.

I think we need better feedback there if SRTM data is not available (maybe just show no AGL?)

Cheers, Felix

On Sat, Mar 22, 2014 at 5:58 PM, Kadir ÇİMENCİ <address@hidden> wrote:

Thanks Felix,
These documents are so helpful but i cannot find the right answer. On the attachment, i tried to make a sample flightplan on Gcs. GROUND_ALT: 147m (the ground altitude above mean sea level)

ALT : 152m (default altitude above sea level for the waypoints)
I set the altitude of wp2 as 162m(Gcs mentions it is an AGL)
But Gcs creates the flight plan .xml with a "wp2" of;
<waypoint alt="162.0" name="wp2" x="-58.8" y="-16.4"/>

with "alt" parameter, not "height" parameter. According to my understanding, it must be hmsl altitude mentioned on Waypoint edit window of Gcs screen ?

Thanks for help..

Kadir

2014-03-22 15:58 GMT+02:00 Felix Ruess <address@hidden>:

Hi Kadir,

as described on https://wiki.paparazziuav.org/wiki/Flight_Plans#Waypoints you can either set waypoint altitude AboveSeaLevel (hMSL) or height which is relative to the ground_alt you set in your flight plan (not a true AGL, as it is only relative to your initial ground altitude and not to over the hill you might be currently flying).

Internally waypoints are stored relative to your initial reference point (either flight plan position/alt or updated after NavSetGroundReferenceHere() was called).

Does that answer your question?

See also https://wiki.paparazziuav.org/wiki/Altitude_definitions

Cheers, Felix

On Fri, Mar 21, 2014 at 9:57 AM, Kadir ÇİMENCİ <address@hidden> wrote:

By the way , lla.alt seems altitude above ellipsoid then converted back to enu.. it seems to me the new waypoint's altitude is AGL too..

2014-03-21 10:52 GMT+02:00 Kadir ÇİMENCİ <address@hidden>:

Hello everyone,

I am a liitle bit confused about the altitude levels in flight plan. Editor accepts an AGL level for a waypoint but in 'navigation.c';

waypoints[i].z = POS_BFP_OF_REAL((wp_tmp_float[i].z - GROUND_ALT))

subtracts GROUND_ALT which seems to me hmsl..

On the other hand the datalink accepts the new waypoint altitude as the altitude above MSL in datalink.c with;

lla.alt = DL_MOVE_WP_alt(dl_buffer)*10 - state.ned_origin_i.hmsl +

state.ned_origin_i.lla.alt;

Can you help me? Thanks..

Kadir

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From:	alonso acuña
Subject:	Re: [Paparazzi-devel] AGL or MSL in flight plan
Date:	Mon, 24 Mar 2014 22:14:25 -0600