Hi Forum - first of all, posting in Aerial photography topic as thought it was the most appropriate, please someone correct me if this should be in a different area.
In summary
I'd like to select the best most appropriate airframe to perform camera tracking missions to film activities like snowboarding, skiing, mountain biking.
What I have found so far
It seems that their is very little information on the subject,
I found this page on the legacy manual which is no longer updated.
Then, I looked in the updated wiki to find a page on camera stabilization, which is a start, but doesn't include information on camera tracking - now, if this is all you have to do to enable camera tracking and gimbal setup, that's great, however I'm sure there would be more examples of this if it was this easy...
There is a link on the camera stabilization page which should give information on camera tracking, however from reading, it only looks like it is to do with antenna tracking, not camera tracking.
Some more googling revealed various posts on the subject, with little or no information on how it can be achieved...
2011 post with some code , a post requesting examples , tarot gimbal question , code not compiling , a similar post requesting information , some queries.
This next link deserves a bit more of an explanation, It seems a camera tracking feature has been developed, but the instructions state that the camera can only point to the right, and only 45 degrees to the left. If this is correct, how would the gimbal be able to focus on a point 90 degrees to the left. does the plane simply fly right hand circuits of the target?
More Recently in Jan 2013, Tristan tried to do something similar tracking a snowboarder with a quad
more promisingly, it looks like a system has been developed that tracks a gps point, a camera gimbal on a fun cub - however I have found little information on how this is achieved in this example.
Some background
I have experience with the Arduplane setup and have been doing basic mapping with a pair of X5's and Canon cameras pointing straight down. I have relatively good success with this. But am ready to move to a new challenge!
I'd like to build a setup that is capable of taking video of a certain point on the ground (fixed waypoint and moving groundstation). I started searching around for this type of information and have found next to nothing in the way of examples of this functionality in use.
I am guessing that the 'point camera here' function of the APM planner manipulates a servo controlled gimbal to point the camera at a certain chosen point on the ground.
My question is this, what kind of airframe would be best for this, fixed wing or multirotor? I know I can achieve 20 minutes of flight time with either, if built well.
What to do next
I could try to fit a roll gimbal to the underneath of a fun cub to test the mechanics of a gimbal, as I have a fun cub in the box I could power with an APM 2.5.
or......Get some sort of multi-rotor.
Due to the huge lack of any evidence to support that this works - I am not sure whether or not to pursue the challenge! however, if anyone has achieved this - then please let me know!
Cheers
Replies
So many questions! :)
For tracking you need a gimbal with tilt/pan/roll. Others can already be discarded. The gimbal also must have GPS support, because it wouldn't be able to figure out where you're pointing at. Even then, it'd probably assume a point at 0 altitude on the geoid (WGS84), instead of actual geometry, otherwise it needs access to DTM information.
There are two approaches; one that integrates with the flight controller and others that use a standalone IMU yet is connected to a GPS through the AP for example. The difference is that a standalone IMU on the gimbal allows you to not worry about the FC it's integrated with. The other requires a specific brand/project for the AP as well.
Multirotors by far are a lot easier to do this work with. MR's can temporarily hold still in the air allowing the subject time to get moving. On a plane you need to synchronize when the person should start moving and you're a lot more limited in choosing how you want to direct the shot. As the plane is always moving, physics dictate it for you.
Gimbals on planes make a bit more sense for surveillance at higher altitudes, as this reduces the travel that a gimbal needs to perform to keep a subject in view. This is at the cost of resolution and definition however, since the subject is further away. You can do it with planes, but as the previous paragraph shows, more accurate planning is necessary either in terms of synchronization or flight planning.
Align has a gimbal (G800) where you basically manipulate the rotation axises to look at a subject. The software than calculates what you're looking at when you're moving to that point and maintains the rotations 'correctly'. It does need to make some assumptions on the current altitude of the vehicle to figure out angles.
The other complexity is thus how you communicate with a vehicle what you're looking at. You can have the vehicle calculate what you're looking at a la align, but you can also apply a ground station approach where you upload coordinates.
If you're trying to do aerial filming work, for all the reasons above, I think it makes a lot more sense to consider a helping hand framing the shot for you. You'll get a lot more flexibility, because once you're piloting the craft you're not likely to have a lot of time figuring out how to instruct the craft what the look at. A second person has all the time to do this and you communicate all the complexity with people instead of clumsy computers.