From: email@example.com (Joseph N. Hall) Organization: GORCA Systems Inc. Date: 15 Mar 96 01:05:25 References: 1 2 3 Followups: 1
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In article <airliners.1996.345@ohare.Chicago.COM> Tom Speer <firstname.lastname@example.org> writes: >However, if you talk to the >Defense Mapping Agency folks that put together the data, they will tell you >that the data are NOT, repeat NOT, reliable enough to serve as the sole >means of terrain avoidance. My fiancee is a PhD candidate digital cartographer, and she can talk to you at length about the obvious discrepancies found in the publicly available elevation datasets. Really, really blatant stuff, like missing or gratuitous peaks. My assumption is that if extremely accurate datasets exist they are classified or in production. Also, there are the storage requirements ... let's say CONUS is roughly 1500 x 3000 mi, sampled at 100ft intervals to a 16-bit accuracy ... this means we need 4.5M x 52^2 x 16 bits = 22GB ... and how will all that data be collected with verifiable accuracy? Why not just turn on the radar altimeter and watch out for blinking red lights.