Iris+, With Gimbal, Mission Planner, ROI

This is a general pre-sales question. I’ve seen a number of Youtube videos about DroidPlanner2 and Region Of Interest. This is the feature I need. My question is multi-faceted and I’m looking at the Iris+ as a starter bird for aerial videography.

  • Is the gimbal “height aware” AGL? i.e can I have it focus on the coordinates and 20 feet above? i.e if I was trying to keep the top of a 100 foot tower in center, would it remain in center of FOV wether I was at 100 foot AGL or 250 foot AGL, and wether I was 50 feet away or 300 feet away.

  • If the answer to above is “yes” then what means does the mission planner software go about determining initial ground level reference point? Does it get this as feedback from the copter GPS or from elevation data from Google maps?

  • How accurate is the Iris+ GPS in determining Altitude above MSL and how accurate does this translate into the mission planner software when you’re as concerned about height AGL as you are lat/lon position?

  • Or perhaps the Mission planner gets an altitude fix at startup from bird’s GPS then uses this as “zero” then adjust the parameters accordingly and then sends the appropriate commands? What if you were at the bottom of a 100 foot hill and wanted to fly “up the hill” autonomously? Is this possible? I assume the software would not be aware of the hill so the user would have to adjust waypoints altitudes accordingly?

  • Is there any feedback to the controller radio as to where the gimbal is positioned using “earth level” as a reference point? i.e can I know if I’m shooting level, or 20 degrees downward (assuming a level attitude)? I would not be using FPV so I’m just curious how one knows how the camera gimbal is positioned in terms of degrees from a “level reference point”

Lots of questions … maybe I’m over-thinking this. Thanks.
Robert in Texas

The gimbal is not height aware. The Pixhawk flight controller is height aware and does position the gimbal at the correct angle for that height.

Mission Planner does not do the calculation. The Flight controller does. It sets the height at 0 meters from where it is sitting on the ground. Mission planner sets the command with your height and location.

Height is determined by an internal barometer and not necessarily by GPS. Height is not exact as it can move up and down based on wind and air pressure changes.

Correct to fly up a hill require a waypoint set at 100 meter above your position and would also cause a failsafe as FAA rules say no higher than 100 meters or 400 feet.

No feed back other than you can monitor the PWM output to the gimbal and convert that to an angle. The best bet is to have an FPV so you can see what your filming. I found being off by as much as 10 degrees can make a difference in the shot your trying to get.

Also things can be smaller than you expect and distance can be a factor.


Good reply. I appreciate it. I realize GPS elevation accuracy is not very good but I didn’t realize they’d consider barometric changes as or more accurate. But I guess it’s something. Can’t fly autonomously without some means of determining an approximation of AGL.

You can disable the Geofence and other failsafes like the bird losing comms with either telemetry or your controller. Obviously not recommended unless you know what you’re doing, but you can send it on completely autonomous missions. The FAA rules being used right now are derived from RC rules and they’re likely to completely change over the next few years. Some licenses have been granted for various operations and they seem to favor operators with at least a private pilots license. So I’m mentioning this because if, low and behold, the FAA does come out with formal FAR/AIM’s for commercial and private operators this year, and there are licenses that allow autonomous missions out of sight, the IRIS+ is future-proof.

Also wanted to mention that if flying up a hill, the following tool in mission planner is a godsend: Right click on flight plan map > Map Tool > elevation graph. It has both google maps elevation data and the space shuttle radar data that you can compare to your planned flight AGL height to determine if you’re going to fly into the ground. I always use this as a sanity check for every mission.