<HTML dir=ltr><HEAD><TITLE>Re: [Liblas-devel] Squeeze me</TITLE>
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<DIV dir=ltr><FONT color=#000000 size=2 face=Arial>Actually, what is the "spatial order" of data that is tilted due to a non-0/90/180/270-degree flight path?</FONT></DIV>
<DIV dir=ltr><FONT size=2 face=Arial>What you really need is a spatial lookup -- not spatial ordering....there is no such thing as "spatial ordering" unless you'lre talking about sorting just along one axis (x,y, or z).</FONT></DIV>
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<DIV dir=ltr><FONT size=2 face=Arial>The LIDAR guys aren't polite enough to collect perfectly aligned lat/lon routes.</FONT></DIV>
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<DIV dir=ltr><FONT size=2 face=Arial>If you want to be able to easily do spatial queries try using SQLITE and turn on the RTree. An RTree is kind of a waste for a fully populated LIDAR cloud but it should work just fine.</FONT></DIV>
<DIV dir=ltr><A href="http://www.sqlite.org/">http://www.sqlite.org/</A></DIV>
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<DIV dir=ltr><FONT size=2 face=Arial>We just built our own indexer so we could say "give me all points within N meters of here" rather than using an RTree or such.</FONT></DIV>
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<DIV><FONT color=#000000 size=2 face=Arial>Michael D. Black</FONT></DIV>
<DIV><FONT size=2 face=Arial>Senior Scientist</FONT></DIV>
<DIV><FONT size=2 face=Arial>Northrop Grumman Mission Systems</FONT></DIV>
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<FONT size=2 face=Tahoma><B>From:</B> liblas-devel-bounces@lists.osgeo.org on behalf of Hamish<BR><B>Sent:</B> Mon 3/8/2010 5:27 PM<BR><B>To:</B> Liblas-devel@lists.osgeo.org; Etienne Bellemare Racine<BR><B>Subject:</B> Re: [Liblas-devel] Squeeze me<BR></FONT><BR></DIV>
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<P><FONT size=2>Etienne wrote:<BR>> I was wondering if it would be possible, to add an option to also<BR>> order the points coordinates in a spatial order instead of<BR>> (I think) a temporal one, it would be much faster to scan<BR>> the file that way to extract any point. within a given<BR>> coordinate. Would it enter in the laszip specifications ? Of<BR>> course, it would be much slower to write, I know, but it<BR>> would be for a longtime gain in speed of reading. What do<BR>> you think ?<BR><BR>I have no problem with optional switches, but realize that this<BR>is a lossy operation, there is useful info in the temporal order.<BR>e.g. if some glitch makes the nav go wonky for 5 minutes or<BR>calibration drifts with time (eg temperature), you can filter<BR>it out if still stored in sequential order.<BR><BR><BR>regards,<BR>Hamish<BR><BR><BR><BR> <BR>_______________________________________________<BR>Liblas-devel mailing list<BR>Liblas-devel@lists.osgeo.org<BR><A href="http://lists.osgeo.org/mailman/listinfo/liblas-devel">http://lists.osgeo.org/mailman/listinfo/liblas-devel</A><BR></FONT></P></DIV></BODY></HTML>