pgLatLon

diff README.html @ 11:7c1c76e7d341

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Updated README.html file (from README.mkd)
author jbe
date Fri Sep 02 14:08:17 2016 +0200 (2016-09-02)
parents 2b7aea022117
children 4489b4d7d9c8
line diff
     1.1 --- a/README.html	Fri Sep 02 14:08:01 2016 +0200
     1.2 +++ b/README.html	Fri Sep 02 14:08:17 2016 +0200
     1.3 @@ -1,17 +1,20 @@
     1.4 -<html><head><title>pgLatLon v0.1 documentation</title></head><body>
     1.5 -<h1>pgLatLon v0.1 documentation</h1>
     1.6 +<html><head><title>pgLatLon v0.3 documentation</title></head><body>
     1.7 +<h1>pgLatLon v0.3 documentation</h1>
     1.8  
     1.9  <p>pgLatLon is a spatial database extension for the PostgreSQL object-relational
    1.10  database management system providing geographic data types and spatial indexing
    1.11  for the WGS-84 spheroid.</p>
    1.12  
    1.13  <p>While many other spatial databases still use imprecise bounding boxes for many
    1.14 -operations, pgLatLon supports more precise geometric calculations for all
    1.15 -implemented operators. Efficient indexing of geometric objects is provided
    1.16 +operations, pgLatLon aims to support more precise geometric calculations for
    1.17 +all implemented operators. Efficient indexing of geometric objects is provided
    1.18  using space-filling fractal curves. Optimizations on bit level (including
    1.19  logarithmic compression) allow for a highly memory-efficient non-overlapping
    1.20  index suitable for huge datasets.</p>
    1.21  
    1.22 +<p>pgLatLon is a lightweight solution as it only depends on PostgreSQL itself (and
    1.23 +a C compiler for building).</p>
    1.24 +
    1.25  <p>Unlike competing spatial extensions for PostgreSQL, pgLatLon is available under
    1.26  the permissive MIT/X11 license to avoid problems with viral licenses like the
    1.27  GPLv2/v3.</p>
    1.28 @@ -249,6 +252,26 @@
    1.29  <p>The <code>&amp;&amp;</code> operator is commutative, i.e. <code>a &amp;&amp; b</code> is the same as <code>b &amp;&amp; a</code>. Each
    1.30  commutation is supported as well.</p>
    1.31  
    1.32 +<h4>Lossy overlap operator <code>&amp;&amp;+</code></h4>
    1.33 +
    1.34 +<p>Tests if two geographic objects may have at least one point in common. Opposed
    1.35 +to the <code>&amp;&amp;</code> operator, the <code>&amp;&amp;+</code> operator may return false positives and is
    1.36 +currently implemented for:</p>
    1.37 +
    1.38 +<ul>
    1.39 +<li><code>epoint &amp;&amp;+ ecluster</code></li>
    1.40 +<li><code>ebox &amp;&amp;+ ecircle</code></li>
    1.41 +<li><code>ebox &amp;&amp;+ ecluster</code></li>
    1.42 +<li><code>ecircle &amp;&amp;+ ecluster</code></li>
    1.43 +<li><code>ecluster &amp;&amp;+ ecluster</code></li>
    1.44 +</ul>
    1.45 +
    1.46 +<p>The <code>&amp;&amp;+</code> operator is commutative, i.e. <code>a &amp;&amp;+ b</code> is the same as <code>b &amp;&amp;+ a</code>. Each
    1.47 +commutation is supported as well.</p>
    1.48 +
    1.49 +<p>Where two data types support both the <code>&amp;&amp;</code> and the <code>&amp;&amp;+</code> operator, the <code>&amp;&amp;+</code>
    1.50 +operator computes faster.</p>
    1.51 +
    1.52  <h4>Distance operator <code>&lt;-&gt;</code></h4>
    1.53  
    1.54  <p>Calculates the shortest distance between two geographic objects in meters (zero

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