The camera/sensor pages show images from equipment that are part of various research projects, and is not a guaranteed operational service, and may produce incorrect data. If you use the data for anything serious, at least check the time stamps (but don't even trust those!).
Not all cameras and/or sensors are HPWREN owned, and may belong to an HPWREN collaborator.
It is inappropriate use of materials found on this web site, including images, videos and other products, if HPWREN is not credited and/or watermark-like imprints (such as text on images or videos) are removed, if only as recognition helps with continued support for the cameras and other sensors.
The individual camera pages typically show the current and differential images, and should automatically reload approximately every minute with updated images. Differential images are built by creating pixel-by-pixel differences between the previous and the new image, which is useful as a noise suppressor to only show what parts of an image has changed. In addition a page may show references to motion detect images, as automatically collected by a camera, and real-time generated animations of the individual images.
NOTE: The cameras page is accessed by many and hence consumes significant bandwidth and processor resources. Excessive access (e.g., large versions at more than the image update frequency) may result in exclusion.
Frequently asked questions
-- "How often are the images updated?"
Most, but not necessarily all, usually update every two minutes by two data servers, 60-second interleaved to create minute by minute images. The a2/a3 and a4/a5 in the upper left corner text refer to the specific server that collected the image.
-- "Are the yellow-text time stamps accurate?
The yellow-text time stamps in the upper left of the images is added by a centralized data server, and they reflect the actual time of when the server requests an image from a camera. The server should have very quite accurate time stamps, due to its time synchronisation via NTP with other time-accurate systems.
-- "When are the time-lapse animations generated?"
Typically after the end of the three-hour period at 00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00 and 21:00.
-- "How are the animations created?"
The animations are automatically created every three hours from the full sized images using ffmpeg. As of November 2017 it uses:
$cmd="/bin/ffmpeg -framerate 4 -pattern_type glob -i \"$dirname/$CAMERA/large/$dstamp/$APTAG/*.jpg\" -vcodec libx264 -pix_fmt yuv420p -crf 21 -threads 0 -metadata title=$dstamp-$APTAG-$CAMERA -y $dirname/$CAMERA/temp.mp4";
-- "What is the black dot that appears in the middle of the sun?"
Photon overload on the CMOS imager chip.
-- "How are the differential images created for the motion-detect series?"
pnmarith -diff image-new image-old
-- "What do the camera error images mean"