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    Time lapse recording with the PMW-EX1
    #1
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    Join Date
    Jul 2009
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    Windsor
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    Question
    Let's say I wanted to document the construction of a high rise building with time lapse recording using the PMW-EX1.

    Let's also say that it took a couple of years to build it, and the crew worked in shifts around the clock for 2 years straight with no holidays.

    (I know this is ridiculous, but trust me. My interest is not with construction)

    Ahem.

    The question posed by my colleague was this:

    Is it hard on the camera to be on all day and night for 2 years straight?

    If so, what wears out?

    I know it's a strange question, but at least it's somewhat entertaining.

    Please let me know.

    Shawn



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    #2
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    Jun 2008
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    Athens, Greece
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    Sounds ambitious This is an easy task for professional vision equipment but I doubt consumer electronics equipment is up to the task. It will probably fail soon. The PCBs and components on camcorders are not designed for 24/7 operation, especially in hostile environments. You will get an early failure or very costly repairs if the manufacturer even covers some part of the damage. Depending on quality, you will get sensors issues that compromise image quality also. You have little control over correcting these on a consumer camcorder. But the real problem is not wear, it's capacity to perform the task.

    You need:

    A permanent installation area with some security to install the full system plus a remote location if you need to monitor the process from time to time. Normally, a locked metal case is used for this.

    A machine vision camera head. 720p or 1080p or full frame multimegapixel for progressive CCD. You will record full uncompressed (12bit) of course, preferably in single frames. You can keep bayer or use a solution that can debayer using a realtime debayer on the fly. Easy to do because the frame rate of timelapse is very low. Think of 16bit color TIFF ouput you can easily monitor when checking recording (while it is recording). These cameras will run for years in exteriors if properly installed. The camera will have a little wear after 2 years of use, but nothing serious. The typical waranty covers 2 years of operation is such an environment, because this is the typical environment these cameras work in. The machine head is video, so it will also be able to capture high quality videos of critical moments in construction on demand. You can do this by remote programming without visiting the site.

    An embedded windows/intel platform for putting right next to the camera or a remote pc with GigE connection. In the second case, you will need to run a fat/long 12V power cable to the camera. One of the high end GigE cables designed for use in exteriors will be fine. I don't recommend using an external host pc for a critical task like this but you should use one for getting a copy of the image, so you have a backup in case something goes wrong. Embedded is the way to go but store remotely for backup. If something fails (vandals, equipment failure) you will be able continue the task and only lose a couple of days of acquisition.

    Some vision software to use with the camera. This will acquire, process, store and provide feedback in case something goes wrong. It can email you if a single frame does not acquired or send a frame daily to your email or ftp account. You can have peace of mind with it. This way you will not spends hours troubleshooting. Since this is mission critical, I think you should get an expert for this. Special processing for calibration of the camera head and color output and remote monitoring are not easy tasks. The camera will certainly require flat field and color calibration, perhaps even temperature calibration depending on the constantly changing environment. It depends on how good you want it to be. It can look a lot better than IMAX cinema though with some work. A custom design can change the night time exposures automatically to produce beautiful images in night exposures with zero noise, correct CCD smear you might get from the sun, etc. You can even do night versions of the building, generally you can get unlimited possibilities.

    This will probably cost about 20,000 euro if you hire someone to engineer and build it. It's a little expensive for using in a single situation but perhaps you could use it again. Equipment that can handle such tasks without wasting user time are very rare.

    You can experiment with it yourself by using a cheap laptop and a cheap machine vision head. About 1500 euro perhaps total for 720p. But don't expect to get professional quality without engineering the image processing.

    You can also hack a DSLR with a laptop to do it. Sounds tricky though.
    Last edited by Otis Grapsas; 07-29-2009 at 12:13 PM.


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