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	<title>George MacKerron: code blog</title>
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	<link>http://blog.mackerron.com</link>
	<description>GIS, software development, and other snippets</description>
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		<title>Sunrise and sunset times with PostGIS and PL/R</title>
		<link>http://blog.mackerron.com/2012/10/15/sunrise-sunset-postgis-plr/</link>
		<comments>http://blog.mackerron.com/2012/10/15/sunrise-sunset-postgis-plr/#comments</comments>
		<pubDate>Mon, 15 Oct 2012 16:52:07 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[GIS]]></category>
		<category><![CDATA[PL/R]]></category>
		<category><![CDATA[PostGIS]]></category>
		<category><![CDATA[SQL]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1202</guid>
		<description><![CDATA[Since light can affect happiness, two important pieces of environmental data I add to the Mappiness data set during analysis are: (1) whether a response was made in daylight; and (2) day length when and where the response was made. To derive these, I need the date, time and location of the response, and sunrise [...]]]></description>
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		<slash:comments>1</slash:comments>
		</item>
		<item>
		<title>Fixing Bluetooth sleep issues with MacBook and Magic Trackpad</title>
		<link>http://blog.mackerron.com/2012/10/11/bluetooth-sleep-macbook-trackpad/</link>
		<comments>http://blog.mackerron.com/2012/10/11/bluetooth-sleep-macbook-trackpad/#comments</comments>
		<pubDate>Thu, 11 Oct 2012 12:55:45 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[Mac]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1214</guid>
		<description><![CDATA[We have an old MacBook (the original white Intel model from 2006) running EyeTV as our telly. Apple&#8217;s Magic Trackpad makes a handy remote control for this setup. Unfortunately, Bluetooth on the old MacBook is highly temperamental. Built-in Bluetooth regularly fails: out of the blue, the Mac decides that it has no Bluetooth module after [...]]]></description>
		<wfw:commentRss>http://blog.mackerron.com/2012/10/11/bluetooth-sleep-macbook-trackpad/feed/</wfw:commentRss>
		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>Using the OSTN02 transformation in PostGIS</title>
		<link>http://blog.mackerron.com/2012/07/03/ostn02-for-postgis/</link>
		<comments>http://blog.mackerron.com/2012/07/03/ostn02-for-postgis/#comments</comments>
		<pubDate>Tue, 03 Jul 2012 11:59:18 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[GIS]]></category>
		<category><![CDATA[PostGIS]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1148</guid>
		<description><![CDATA[When converting coordinates between WGS84 (GPS) and OSGB36 (UK National Grid), using OSTN02 can gain us a few metres in accuracy over the basic parametric transformation provided by PostGIS&#8217;s st_transform via PROJ.4. Happily, Ordnance Survey now distribute an NTv2 version of the OSTN02 transformation, courtesy of the Defence Geographic Centre, which can be used by [...]]]></description>
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		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>Objective-C SHA1 categories for NSData and NSString</title>
		<link>http://blog.mackerron.com/2012/06/19/sha1-category-nsdata-nsstring/</link>
		<comments>http://blog.mackerron.com/2012/06/19/sha1-category-nsdata-nsstring/#comments</comments>
		<pubDate>Tue, 19 Jun 2012 09:12:36 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[iPhone]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1127</guid>
		<description><![CDATA[I recently needed to calculate a SHA1 hash in an iOS app. In iOS4+ it&#8217;s possible to use CommonCrypto, but Mappiness has always supported iOS3. I therefore added NSData and NSString categories to a public domain C implementation instead. This remains public domain: do with it what you will. It relies on a hex-encoding category [...]]]></description>
		<wfw:commentRss>http://blog.mackerron.com/2012/06/19/sha1-category-nsdata-nsstring/feed/</wfw:commentRss>
		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>How to compile PostGIS 2 on Ubuntu Server 12.04</title>
		<link>http://blog.mackerron.com/2012/06/01/postgis-2-ubuntu-12-04/</link>
		<comments>http://blog.mackerron.com/2012/06/01/postgis-2-ubuntu-12-04/#comments</comments>
		<pubDate>Fri, 01 Jun 2012 17:30:01 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[GIS]]></category>
		<category><![CDATA[PostGIS]]></category>
		<category><![CDATA[System admin]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1091</guid>
		<description><![CDATA[PostGIS 2 has some exciting new goodies &#8212; including raster support &#8212; that I&#8217;m keen to use in the analysis of Mappiness data. But the PostGIS package provided by Ubuntu 12.04 is still only at version 1.5, and the GEOS and GDAL packages are also too old to support the new version. So &#8212; this [...]]]></description>
		<wfw:commentRss>http://blog.mackerron.com/2012/06/01/postgis-2-ubuntu-12-04/feed/</wfw:commentRss>
		<slash:comments>5</slash:comments>
		</item>
		<item>
		<title>Spindlytext: write in the sky with the Google Earth API</title>
		<link>http://blog.mackerron.com/2012/05/02/spindlytext/</link>
		<comments>http://blog.mackerron.com/2012/05/02/spindlytext/#comments</comments>
		<pubDate>Wed, 02 May 2012 16:30:19 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[CoffeeScript]]></category>
		<category><![CDATA[GIS]]></category>
		<category><![CDATA[Google Earth]]></category>
		<category><![CDATA[JavaScript]]></category>
		<category><![CDATA[KML]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1066</guid>
		<description><![CDATA[I&#8217;ve just released Spindlytext on Github. It&#8217;s the library that powers the live data display in Pigeon Sim, by creating KML linestrings in the shape of letters. It looks like this:]]></description>
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		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>A depthcam? A webkinect? Introducing a new kind of webcam</title>
		<link>http://blog.mackerron.com/2012/02/03/depthcam-webkinect/</link>
		<comments>http://blog.mackerron.com/2012/02/03/depthcam-webkinect/#comments</comments>
		<pubDate>Fri, 03 Feb 2012 18:21:10 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[CoffeeScript]]></category>
		<category><![CDATA[WebGL]]></category>
		<category><![CDATA[WebSockets]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=1005</guid>
		<description><![CDATA[Update, 10 February: Sorry for some serious reliability issues over the last few days. The streaming server is now hosted in-house at CASA, which should be a lot more robust. At CASA we&#8217;ve been looking at using a Kinect or three in our forthcoming ANALOGIES (Analogues of Cities) conference + exhibition. We&#8217;ve been inspired in [...]]]></description>
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		<slash:comments>21</slash:comments>
		</item>
		<item>
		<title>Polygons from PostGIS to Processing</title>
		<link>http://blog.mackerron.com/2011/11/17/polygons-from-postgis-to-processing/</link>
		<comments>http://blog.mackerron.com/2011/11/17/polygons-from-postgis-to-processing/#comments</comments>
		<pubDate>Thu, 17 Nov 2011 11:28:43 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[GIS]]></category>
		<category><![CDATA[PostGIS]]></category>
		<category><![CDATA[Processing]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=942</guid>
		<description><![CDATA[There are plenty of ways to get spatial data from a PostGIS database into a Processing sketch. You can export to CSV or SVG and load it from there; you can query the database directly; or, depending on context, you might choose to generate Processing commands directly, which is the route I went to display [...]]]></description>
		<wfw:commentRss>http://blog.mackerron.com/2011/11/17/polygons-from-postgis-to-processing/feed/</wfw:commentRss>
		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>Passcode view controller</title>
		<link>http://blog.mackerron.com/2011/10/28/passcode-view-controller/</link>
		<comments>http://blog.mackerron.com/2011/10/28/passcode-view-controller/#comments</comments>
		<pubDate>Fri, 28 Oct 2011 16:33:25 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[iPhone]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=511</guid>
		<description><![CDATA[Need to protect something with a passcode in an iPhone app you&#8217;re developing? Then you may find my MIT-licensed passcode view controller &#8212; as seen in the mappiness app and in the short screencast below &#8212; of use. See Github for the code and (scant) documentation. Download video as MP4, WebM, or Ogg.]]></description>
		<wfw:commentRss>http://blog.mackerron.com/2011/10/28/passcode-view-controller/feed/</wfw:commentRss>
		<slash:comments>0</slash:comments>
		</item>
		<item>
		<title>Approximating kernel-weighted proportions in PostGIS</title>
		<link>http://blog.mackerron.com/2011/08/16/kernel-weighted-proportions-postgis/</link>
		<comments>http://blog.mackerron.com/2011/08/16/kernel-weighted-proportions-postgis/#comments</comments>
		<pubDate>Tue, 16 Aug 2011 13:27:23 +0000</pubDate>
		<dc:creator>George</dc:creator>
				<category><![CDATA[GIS]]></category>
		<category><![CDATA[PostGIS]]></category>
		<category><![CDATA[SQL]]></category>

		<guid isPermaLink="false">http://blog.mackerron.com/?p=864</guid>
		<description><![CDATA[Imagine you want compare various locations in terms of the availability of a certain type of environment, such as fresh water. You might want to use a measure of the proximity of that environment &#8212; such as the nearest neighbour distance. You might want to use a measure of the quantity of that environment in [...]]]></description>
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		<slash:comments>0</slash:comments>
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