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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi Bruce,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><tt><span style='font-size:10.0pt'>“What approaches
are people using with large Lidar datasets?”<o:p></o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:10.0pt;color:#1F497D'><o:p> </o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>You might take a look at the WeoGeo group. They are a commercial
operation, not FOSS, but they are throwing dedicated AWS instances at the issue
of lidar file serving. The dedicated instance, I gather, is for the sole use of
the download client with any clip, re-project, or re-format processing requested.
Paul Bisset would be happy to clarify. <a
href="http://www.weogeo.com/">http://www.weogeo.com/</a> <o:p></o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Some more details here: http://www.cadmaps.com/gisblog/?p=25<o:p></o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The lidar itself is I assume a raw file, probably split into a
set of S3 objects which are stream concatenated and run through the processing
instance and out to the requestor. Since the data sets are very large the
dedicated assignment of a temporary cpu or two is justified.<o:p></o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></tt></p>
<p class=MsoNormal><tt><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Beyond that I would like to see at least some lidar sets treated
like the JPL srtm which is made accessible via WMS with pixel coded elevation as
grayscale. Paul Ramsey’s inimitable advice would work well for lidar too.
The end client can turn a WMS request on a lidar image pyramid behind say
Geoserver into whatever is desired, in my case I would turn it into 3D xaml meshes.
I imagine this could be done in a more standards compliant manner through
the WCS spec. I believe that the JPL srtm was made public before an implementation
of WCS was accessible. <o:p></o:p></span></tt></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>http://onearth.jpl.nasa.gov/index.html<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.5pt;font-family:"Arial","sans-serif";
color:black'>The default <i>styles</i> for the elevation layers are a version
of the elevation maps scaled to 8 bit. The full elevation values can be
retrieved from this server by requesting the <i>short_int</i> or <i>feet_short_int
styles</i> in combination with the <i>image/png</i> <i>image/geotiff</i> or <i>image/tiff</i>
value for the <i>format</i> argument. The result of such a request will be an
image where the signed short integer values contained in the image file for
each pixel are the elevation of the respective point on the map, in either
meters or feet. The base data is in meters. The <b>us_ned</b> <i>layer</i> base
data is floating point real numbers in meters, data which can be retried in
tiff or geotiff format when using the <i>real</i> or <i>feet_real</i> as
styles.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:8.5pt;font-family:"Arial","sans-serif";
color:black'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I like the interchange of comments on this subject . In the end
I’m inclined to stick with the simplicity of file storage for imagery. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Thanks<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Randy<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#4F81BD'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
discuss-bounces@lists.osgeo.org [mailto:discuss-bounces@lists.osgeo.org] <b>On
Behalf Of </b>Bruce.Bannerman@dpi.vic.gov.au<br>
<b>Sent:</b> Thursday, February 21, 2008 6:25 PM<br>
<b>To:</b> OSGeo Discussions<br>
<b>Subject:</b> Re: [OSGeo-Discuss] Image Management in an RDBMS...(was OS
Spatial environment 'sizing')<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
<tt><span style='font-size:10.0pt'>IMO:</span></tt> <br>
<br>
<tt><span style='font-size:10.0pt'>Paul,</span></tt><span style='font-size:
10.0pt;font-family:"Courier New"'><br>
<br>
<tt>> </tt><br>
<tt>> On Feb 21, 2008, at 4:19 PM, Bruce.Bannerman@dpi.vic.gov.au wrote:</tt><br>
<tt>> ></tt><br>
<tt>> > What it comes down to is what is appropriate for your use case.</tt><br>
<tt>> </tt><br>
<tt>> Indeed! However, there seem to be vanishingly few use cases for which
</tt><br>
<tt>> raster-in-database is actually the more appropriate solution.</tt><br>
<tt>> </tt></span><br>
<br>
<tt><span style='font-size:10.0pt'>;-) I beg to differ.</span></tt> <br>
<br>
<span style='font-size:10.0pt;font-family:"Courier New"'><br>
<tt>> (BTW, point-in-time recovery, a nice example of a place where database
</tt><br>
<tt>> semantics have an upper hand. Although more modern file systems
and </tt><br>
<tt>> enterprise backup systems are pretty competitive now... even a </tt><br>
<tt>> relatively simple hack like the OS/X Time Machine feature solves that
</tt><br>
<tt>> problem for-all-practical-purposes.)</tt><br>
<tt>></tt></span> <br>
<br>
<br>
<tt><span style='font-size:10.0pt'>Trying to manage very large regional
datasets via a file based solution is problematic as described earlier with
tile based approach to vector data in particular. Again for my use case the DB
is better.</span></tt> <br>
<br>
<br>
<tt><span style='font-size:10.0pt'>Just to throw in another related issue:</span></tt>
<br>
<br>
<tt><span style='font-size:10.0pt'>Lidar systems are throwing out an enormous
amount of data. I had one dataset of only around 17 million odd records several
years ago (of course stored in our corporate db ;-) ) that we could not handle
with ArcGIS Desktop (v9.1). From memory it was a 32bit issue.</span></tt> <br>
<br>
<tt><span style='font-size:10.0pt'>What approaches are people using with large
Lidar datasets?</span></tt> <br>
<br>
<br>
<tt><span style='font-size:10.0pt'>Bruce</span></tt> <br>
<br>
<o:p></o:p></p>
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