T H E  C A P T U R E   U N I T S   W I L L   C O N S I S T   OF:

   Robust case with suitably adaptable mounting hardware and a glass face. 

   Camera, adjustable lens, CMOS chips, capture & compression hard & software.

   Photosensor  to trigger frames at matching lighting conditions.

    Memory module to store the images between uploads.

    A network device to transmit images and telemetry.

    Photovoltaic power system including batteries.

 

Image stability and registration should be achieved primarily  by fabricating a stable platform.  Inclusion of visible registration marks within the frame would allow for re-alignment of images.  Some off-the-shelf network camera systems may be able to be adapted, but in any event, the technology for all of these aspects is readily available, or easily developed. Large format CMOS chips may be preferable to CCDs, which for standard consumer and video applications require the ablity to capture at short exposures, which we do not require. Also, future image standards will be much higher resolution than is currently available and should be anticipated as much as possible. A telemetry system with sensors to report the status of capture unit to the network should also be included.

Consistancy of lighting effects from frame to frame will be maintained over time by the use of sun angle and spot metering of key image elements. An algorithym will select moments for optimal exposures, from which the frames most consistant with the previous days' images will be selected for upload to the network from the memory cache .

Keeping the lens clean over long periods may be a challenge, but could be accomplished in a number of ways. The most maintenance free might be using an electric motor to periodically spin a disk of glass serving as the first element, and thereby disperse any contaminants. This would not maintain a perfectly clean surface, but should be able to maintain a consistent view.

A perfectly clean surface could be achieved with an roll of moving plastic film that would advance periodically when triggered by a photo sensitive sensor detecting the scattering caused by contaminants on the surface. An air or water jet could also be used, but these would all require some differing amounts of periodic maintenance.