The WebCam, web pages and the National Center for Atmospheric Research are sponsored by the US National Science Foundation (NSF).
This WebCam is operated by NCAR's Lidar Engineering Group of the Atmospheric Technology Division. The WebCam was brought on-line to monitor sky conditions as part of an aerosol backscatter lidar development effort. The images from this camera have been made available to the public as a simple by-product of archival work associated with these images. NCAR makes no warranty concerning the continued availability of these images, or the utility of these images for any purpose. The WebCamera may be taken off-line or re-pointed at any time.
The camera is located on the roof of the NCAR Foothills Lab, near the intersection of Foothills Parkway and the Diagonal Highway in Boulder, CO. This is also near the Boulder airport, and aircraft are often seen by the camera during takeoff or landing. Since 2003-Jun-05, the camera has been centered on the east side of one of the Lab's buildings, and looks north along the foothills of the Front Range. The camera uses a wide-angle lens, which accounts for the distortion seen in the images. Resolution of the camera is set to 640x480 pixels, with an image archived typically every minute. On a clear day, the camera can see as far as Horsetooth Rock, directly to the west of Fort Collins (when seen, it is on the horizon, just to the left of center in the image).
The full-resolution images from the camera have a byte-size of 60 KByte to 100 KByte. These images can take considerable time to download over telephone modems (typically on the order of 20 seconds for a 56Kbit connection). A reduced-size and reduced-quality set of images is available for use in the historical "review" mode, in an attempt to limit bandwidth requirements. See more details.
Not counting download time, the "real time" images shown here may be as much as two minutes behind clock time. This is due to latencies associated with executing the code to grab the image from a local storage disk (the code "sleeps", and wakes only once per minute), and some small amount for internal network transfer and processing.
The pages and the software for the WebCam have been done on a "time available" basis. There will be only very limited time in the future for improvements.
The following are on my list of desires, based upon my concerns and user input:
- Use of URL arguments to allow bookmarking movie loops for certain specific time periods (start and end); this will allow building of an "interesting events" log.
- Change the control buttons so they conform more closely to accepted practices for VCR/DVD players.
- Diagnostics to let a user know when they have selected a non-existent time period (defined as a time prior to the beginning of camera operations, or after today's date/time, or just for a period when the camera was down).
- Selection of the minimum time between images (currently, all images within a time period are reviewed; for long periods of time, a user might wish to select a longer gap between images.
- For the static image page, it has been decided to not provide automatic update of the image. We have concerns about many users invoking such an option, and impacting our web server.
Lesser (lower priority) changes may include:
- Use of a "slider" for speed selection (utility is somewhat doubtful: a relative setting of faster/slower seems to better suit needs).
- Add code to "accelerate" the movie progression, once image download is complete (and the images are in either your browser's memory or disk cache).
The following have been done:
- 030624: The movie loop may not include the "last available" image: check indices of arrays.
- 030623: A clear display of the current image time (date/time in a readable format)
- 030619: Addition of an initial "connection speed" selection, prior to the "Submit" button (leftmost panel).
- 030619: A change in the default "come-up" mode, so that "Loop" is On, and images automatically start playing.
Yes, there are known bugs. Some should not be hard to fix, but others derive from the asynchronous timing of the event handlers (every time you click a button, you invoke an event handler in this code). The asynchronous problems vary with the Browser, and can be affected by any impatience on the part of the user; these problems are not likely to ever be fully fixed.
- Movie freezes at a certain frame during every pass. This is an async problem, and has to do with the "image complete" status being corrupted when the faster/slower buttons are clicked. You may reload just the display frame, and this is likely to fix the problem. Avoid the problem by not changing movie speed during frame loading. This can be fixed, but then it will take longer to load a movie.
- The number-of-days-per-month can be wrong for the initial month displayed in the selection form.
- On reloading the viewer page, the proper speed is not always shown in the "InterNet Connection" portion of the form. Alternately, your selected speed may be shown, but the viewer speed does not correspond to what is shown.
- Every now and then, the movie control buttons disappear. This looks like a hard problem to track-down. If this happens, click where the buttons should be. First, stop any movie, then click where the missing controls are. :-) 030701: this problem has been partially mitigated.
The most problematic issue in playing movies is the speed setting. If the movie tries to move through images too quickly, frames will be dropped or appear blank. Be sure to select a proper connection speed when first loading images. After the first pass through the images, they should reside in your browser's cache. At this point, you may greatly increase the speed of the movie for additional loops through the images. [Note: there are reasons the images were not set-up to "pre-load". This allows the tool to be used more easily off-line (say, with images on a CD), and allows the viewer to be a bit more responsive to user commands.]
The grey/red "LEDs" below the image are active LEDs. If you click on an LED, you go to that relative position in the image sequence. This works whether or not the movie is running.