[Canberrauav] choosing cameras Andrew Tridgell andrew at tridgell.net Fri Oct 3 13:07:54 EST 2014 Hi All, As a followup to my "next steps" post, I'd like to open a discussion on what cameras we should look at getting. Right now we fly a PtGrey Chameleon, which is a 1280x960 machine vision colour camera, with USB2 connection. This camera has served us well, but is too low resolution if we want to have a serious go at finding "shoe-sized" objects. The obvious next step would be a higher resolution machine vision camera, either on USB3 or gigabit ethernet. PtGrey offers heaps of those, but they are expensive. For example, a 6MP Grasshopper3 is $2995, and a 9.1MP is $3495. I'm sure they are great cameras, but given we'd need at least two of them it's a big chunk of our budget. There are other manufacturers that offer similar cameras (many with the same sensors inside), but at least for those that put prices on their website the prices seem similar. Another way to go is to use a camera that is a bit more mass-market, which brings the cost down. A lot of people doing aerial mapping use cameras like the Sony Nex7. The issue then is how we trigger the camera and how we get the images into the Odroid within the aircraft. An interesting possibility is to use one of the new range of "lens-style" cameras, like this one: https://developer.sony.com/devices/cameras/sony-smartphone-attachable-lens-style-camera-dsc-qx100/ those cameras were designed to mate to a smartphone via WiFi, and are essentially a camera built into a lens, with remote control and remote image retrieval over WiFi. Could we use something like that in an aircraft, with a wireless adapter on the Odroid? The protocols they talk seem to be just JSON over HTTP, and there is extensive documentation, so it would seem to be possible. Obviously we'd need to test to see if the WiFi interferes with other systems (especially RC control and GPS), but I suspect we could solve that. These cameras incorporate the same range of sensors used in cameras like the Nex7, but without the camera body. There are also versions that take interchangeable lenses: http://store.sony.com/interchangeable-lens-style-camera-zid27-ILCEQX1/B/cat-27-catid-All-Cyber-shot-Q-Series-Cameras That would give us a 20M sensor for 1/5 of the price of a machine vision camera. They have quite large sensors (23.5 X 15.6mm), so I'd hope the sensitivity would be good. By comparison the 6MP Grasshopper3 has a 12.4mm sensor, so sensor area of the "lens-style" camera is about 4x. I haven't checked the datasheets to see if that does translate into increased sensitivity. Cheers, Tridge
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