Terrain data is not being fetched for mission items without GPS

[magicrub]

Terrain data is not being fetched for mission items without GPS

[lvale]

Testing: Copter 3.4RC1

Parameters Terrain_Follow=1 Terrain Spacing=10 Terrain Enable=1.

Plugged PixHawk via USB to Latest MP beta. Draw a mission on MP (12 waypoints). Confirmed that on the Mission Planner/SRTM dir, some files were downloaded by MP (Zip and then HGT). The 12 Waypoints correspond to 2 tiles N39W9 and N39W8.

Uploaded mission to copter but strangely the status screen from the PixHawk keeps showing the following vars all zero:
ter_curalt
ter_alt
ter_load
ter_pend
ter_space

Switched off PixHawk, and verified that the SDCard only has one zero length file on the TERRAIN dir, corresponding to the tile where Home in MP is located, no other terrain tiles were loaded to the SDCard, although they were downloaded my MP and I can confirm they are in the SRTM dir.

If the mission is loaded, shouldn’t the required elevation files for the mission be preloaded, regardless of the current state of the PixHawk being without GPS reception ?

[lvale]

A mechanism to pre-fetch terrain data to the sdcard could be discussed with the GCS owners

[rmackay9]

Another user reported this issue to me today. It's a known issue but just wanted to add a note that it does affect users occasionally.

[CodingGhost]

I also would love a feature to just mark an erea in MP and upload all that terrain data, it could be so easy! @rmackay9

[rmackay9]

@CodingGhost, If users have a mission defined though AP will automatically fetch the required terrain data from the ground station so the user shouldn't need to worry. We actually have very few reports of terrain failsafes which is what happens if the vehicle needs terrain data but doesn't have it.

I think I understand the suggestion but I'm wondering if it's really required.