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Version 1.3:
Maintenance release
PSQ has received extremely little use since it's release six years ago and has stopped working on some platforms and newer browsers. Usage has been increasing over the past year which has brought some of these problems to light. This release is the result of a code shakeout to clean up the different pieces of PSQ and update any dependencies. That alone has gotten PSQ working again in many instances.
Work on enhancements and upgrades to the system has begun and we hope to release an improved PSQ in early to mid 2008.
24 October 2007
Version 1.2:
First operational release
ASCII Tables: ASCII output is now an option for small areas. If you request ASCII output you will receive a table containing the filenames of the data files and the pixel values in those files. Currently the definition of "small area" is "less than 65 pixels". For more information see the FAQ.
Results Preservation: The search results are no longer deleted after a user submits a request. Users wishing to submit more than one request from the same results list no longer need to redo the search each time.
Date Range Validation: The interface is now more lenient about ensuring the date range is valid. Previously, the interface would never allow an invalid date range, even while the user was in the midst of changing it. The interface now waits until the user submits a search request before validating the date range. If the interface finds an invalid date range it warns the user and does not run the search.
Choice Widgets: The Choice widgets in the geographic panel have been replaced with ComboBox widgets that have the same functionality. This circumvents a problem with the plugin on SGI's and Linux boxes in that Choice widgets do not work on those platforms. We have noticed that the ComboBox menu sometimes appears in an odd location (not directly under the widget as expected) but at least it appears.
Request Submission: The interface now submits requests using a POST operation instead of a GET. As a result, request submissions are now faster, though large requests may still take a while.
27 September 2001
Version 1.1b:
Second beta release
Connect Errors: New users sometimes experience difficulty connecting to the database. To the interface it appears that the database is down, however this is not necessarily the case. More commonly, the user is behind a firewall and/or using a proxy server that will not allow a connection to the database port. We now have a more informative error message when this occurs.
Geographic: The geographic panel now has more appealing maps and supports zooming, single pixel requests, and input of (lat, lon) and (row, col) coordinates. The latter should benefit users who wish to request the same subset as a previous request. For more information on the new geographic panel, please see the Geographic section in the help.
Size: To accomodate the much larger geographic panel the size of the entire interface needed to be increased beyond the display capabilities of some platforms. To work around this problem, we removed the map from the geographic panel and made it an independent window. Consequently, the main interface (minus the map) is smaller than before. Since the map is in a separate window, it can be resized which means less scrolling for the larger maps.
Spheres: We had been looking for a package to do the spherical trigonometry for us, but we failed to find one. Consequently we had to code a lot of spherical trigonometry into the PSQ search module to run the orbit and scene search algorithms. Since we were well on our way to writing our own spherical trigonometry package anyway we decided to pull what we had out of the PSQ, expand on it, and make it an actual package. The PSQ now uses the "nsidc.spheres" java package to perform areal comparisons on the sphere and to calculate the values needed for the swath and scene search algorithms. The spheres package is still incomplete, and only the parts the PSQ uses have been tested. For more information see the java documentation or contact NSIDC User Sevices.
Scene Search:The main reason the PSQ has been in beta for so long is the search algorithm for AVHRR scene data did not work very well and, for some searches, could return a high percentage of false positives. We believe this problem has been fixed since our test cases no longer return any false positives. Since we are unable to test every conceivable search we would appreciate feedback from PSQ users who still find a high percentage of false positives (blank data) among their results, so we can improve the search algorithm.
Note: With this release we feel we have fixed all the known bugs. But if you happen across an unknown bug, or witness any bizarre behaviour, we'd appreciate hearing about it.
06 August 2001
Version 1.0b:
Initial beta release
30 November 2000
If you have any questions please contact NSIDC User Services.
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org
