Quote:
Originally Posted by Wavytone
Two solutions used in the rail industry - we have machine vision camera equipment embedded in the ballast looking up at the undersides of rolling stock to inspect brake pads and wheel wear. As you might expect it’s a dirty environment in addition to ordinary dust, rain, leaves, litter and other debris that can fall on the gear.
1. Use a mechanical shutter that protects the window from dirt and only opens before and closes after a picture is taken.
2. Windscreen wipers with fluid to wash the window before a shot is taken. Wipers have advantage that they will push small items off (leaves, etc) but also more of a maintenance problem in requiring regular replacement of the blades, water, and fail frequently.
3. Don’t face the camera up - place horizontally with wide angle lens and a hood over it, and accept the camera cannot view directly overhead.
Anything with moving parts or requiring consumables (wash liquid) is prone to failure and a maintenance headache. Making these solutions work this reliably long-term is neither trivial nor cheap.
Tear-off protectors are also used on motorcycle helmet visors.
Questions for you:
1. do you really need continuous video or would it be ok to take images periodically ?
2. Is this expected to operate automatically at a location which is unmanned for long periods or will there be someone nearby ?
As I hinted before I think you really should be talking to companies that do this for weather stations because what you’re proposing is not new, and has been solved before.
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Thanks for these thoughts. I particularly like the shutter idea. However, given the dome is roughly a foot in diameter, it's going to be fairly large, and then we introduce problems with things possibly getting caught inside, motors failing, etc. Do you have any solutions for removing e.g. leaves, spiders, etc. from inside the camera housing protected by the shutter please?
Interesting idea regarding the windscreen wiper idea. I wonder if they make curved ones to suit this sort of dome, though. I have seen some CCTV dome wiper brushes, though, so they may be more easily used (i.e. they're commercially available). Just did a quick Google. Didn't find any commercially-available curved wiper blades, but I did find something that gave me an idea to run with that may actually be better than a wiper blade.
To answer your questions:
Quote:
Originally Posted by Wavytone
1. do you really need continuous video or would it be ok to take images periodically ?
2. Is this expected to operate automatically at a location which is unmanned for long periods or will there be someone nearby ?
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1. No, they're taking images every five minutes.
2. There will be people nearby, but the cameras are being installed on rooftops, so won't be easily accessible. The system needs to be fully autonomous for as long as possible. I realise I won't be able to get something that lasts forever, but if I can minimise cleaning and maintenance visits by a person to e.g. only once per year, then that'd be beneficial.
I am going to set up a prototype down at the beach soon. I figure that's probably the harshest environment (in terms of sea spray and wind-blown sand hitting the dome) and would be a good place to test these ideas out...
Thanks heaps for your help and ideas.
David