I was thinking to build a quadcopter with a thermal camera. As such, I would like it to be able to lift-off and land automatically. Do I need some kind of range sensor for that, and does APM support it?
My current list of components can be found here. Any advice is very welcome, as this is my first quadcopter.
The barometer is accurate enough for automated take-off and landing. But sonar sensors are relatively cheap (e.g Maxbotix I2C EZ http://www.maxbotix.com/Ultrasonic_Sensors/MB1242.htm or the WR water resistant variant) and give great accuracy up to 7 meters. For accuracy up to 40 meters you can use the LIDAR-Lite. http://pulsedlight3d.com/
Nice idea to use a mobile phone sensor. Would be good the see the results of that project.
Also consider a gimbal, because APM has point and shoot capability, you could fly the drone around whilst focusing on one target you wish to survey.