<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Verdana","sans-serif";
color:#003399;}
.MsoChpDefault
{mso-style-type:export-only;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>Dear geospatial software experts,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>By integrating with GEOS, OGR can perform various spatial
operations on individual geometries, such as buffer, intersection, union, and
so on. Is there a library that efficiently performs these kinds of operations
on entire OGRLayers? For example, this library would have functions that would buffer
all of the features in a layer, or intersect all of the features in one layer
with all of those in another. Basically, I am looking for an open source
technology that replicates the "geoprocessing tools" found in ArcGIS
and other GIS packages. These tools traditionally operate on one or more layers
as input and produce one or more layers as output.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>If such a library does not exist, does the OGR team envision that
they might add such capabilities to OGR in the future? From software design and
performance points of view, would it be appropriate to extend OGR to include
functions for spatial operations on entire layers, or is this best left to
other libraries? I can see rudimentary ways to implement such tools (e.g. for intersecting
layers: loop over all features in both layers, calling OGRGeometry::Touches on
all combinations, or something similar). But I am not a geometry expert and do
not know if OGRLayer's cursor-based design is compatible with such capabilities;
I do not know about spatial indexing, for example.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>I develop open source geoprocessing tools that help with spatial
ecology problems. At the moment, my tools depend on heavily on ArcGIS for these
operations with vector layers. I would like to remove this dependency, and, if possible,
develop a toolbox that exposes the same ecology tools to several GIS packages. Many
GIS packages, such as ArcGIS, QGIS, MapWindow, and OpenJump, support plugin
extensions. I am wondering whether how difficult it would be to develop a
package of tools that does not depend on a specific GIS package but exposes them
to several packages via the package-specific plugin mechanisms. For this to
work, I'd have to find a library that can do the kind of geoprocessing with layers
that ArcGIS can do, or write my own. Writing it myself sounds daunting and am
hoping that there are existing projects to draw from.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>Thank you very much for any comments you can provide.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'>Jason<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:#003399'><o:p> </o:p></span></p>
</div>
</body>
</html>