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RE: Snapshot of US National Airspace Data CD-ROM
I may be completely wrong on this, but my understanding is that NO federal
government produced data can be copyrighted by the govt in any way. I.e. If
the government produced it, you can copy it all you like. Although I don't
know this for certain. I believe it is an exception in the copyright act.
-- Nathan
------------------------------------------------------------
Nathan Neulinger EMail: nneul@umr.edu
University of Missouri - Rolla Phone: (573) 341-4841
Computing Services Fax: (573) 341-4216
> -----Original Message-----
> From: John C. Peterson [mailto:jaypee@netcom.com]
> Sent: Thursday, December 16, 1999 2:06 AM
> To: linux-aviation@nl.linux.org
> Subject: Re: Snapshot of US National Airspace Data CD-ROM
>
>
> On Wed, Dec 15, 1999 at 08:17:02PM -0500, A. Reichert wrote:
> >
> > I may be able to help with the FTP availability. (1) What
> is the total
> > size,
>
> See below...
>
> >and (2) can you tell me for certain that there is no copyright
> > problems?
> >
> > - Alan
> >
>
> Will check on this...
>
> I tried compressing the "raw" NASD fixed length record data files.
> The original files are indeed pretty BIG (total > 245 MB). The good
> news is that I found out they will compress much better than
> I had first
> guessed. They compress to as little as roughly 3% of the original size
> (using bzip2 compression). I calculated a histogram of the "apt.txt"
> file and found that 87.3% of the characters are blanks, so
> these ratios
> are not too surprising in view of that. Using bzip2, all the data is
> less than 8 MB! Here's the nitty-gritty:
>
>
> gzip compression stats:
>
> no compression gzip -1 gzip -9
> ============== ======= =======
>
> aff.txt: 1492194 172587 137010
> apt.txt: 102171238 8268917 6638055
> arb.txt: 905848 52475 33527
> awy.txt: 9074325 1140017 821790
> com.txt: 1016090 91096 72156
> fix.txt: 36673780 1514892 1110183
> fss.txt: 2756449 101375 80508
> hpf.txt: 7819728 810756 645089
> ils.txt: 1929194 287609 228867
> lid.txt: 23571135 1040744 725685
> mtr.txt: 14525280 930474 707117
> nav.txt: 6753480 618244 490246
> oth.txt: 2632531 333050 226927
> pfr.txt: 11299865 421894 301844
> pja.txt: 462324 49602 40023
> ssd.txt: 1578654 212855 162090
> sua.txt: 7024368 319831 215716
> twr.txt: 13074432 705387 526279
> wxl.txt: 289419 68318 57680
> ---------- ---------- ----------
> Totals 245050334 17140123 13220792
>
> Ratios 6.99453 % 5.3951 %
>
> bzip2 compression stats:
>
> no compression bzip2 -1 bzip2 -9
> ============== ======== ========
>
> aff.txt: 1492194 131997 121245
> apt.txt: 102171238 4647535 3735390
> arb.txt: 905848 24679 23231
> awy.txt: 9074325 578409 497476
> com.txt: 1016090 46222 39982
> fix.txt: 36673780 580053 539569
> fss.txt: 2756449 54133 46939
> hpf.txt: 7819728 373526 284158
> ils.txt: 1929194 190893 172369
> lid.txt: 23571135 430320 361081
> mtr.txt: 14525280 451197 387903
> nav.txt: 6753480 359318 326460
> oth.txt: 2632531 164553 159021
> pfr.txt: 11299865 203243 165497
> pja.txt: 462324 32111 30434
> ssd.txt: 1578654 135968 118388
> sua.txt: 7024368 130183 110767
> twr.txt: 13074432 365681 310752
> wxl.txt: 289419 44735 43638
> ---------- ---------- ----------
> Totals 245050334 8944756 7474300
>
> Ratios 3.65017 % 3.05011 %
>
>
> --
> ___|___ | John C. Peterson, KD6EKQ | Try Linux for Intel
> x86, it's the
> -(*)- | mailto:jaypee@netcom.com | Ferarri of 32 bit
> operating systems!
> o/ \o | San Diego, CA U.S.A | See
http://www.linux.org/ for info
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