[postgis-users] dynamic segmentation

Paul Ramsey pramsey at refractions.net
Thu Nov 16 21:16:53 PST 2006

As with many things, the terminological environment has been muddied by 
the conflation of specific ESRI terms for particular features with 
generic terms for the similar things.  Call it the "Chesterfield effect".

ESRI "Dynamic segmentation" is really just "linear referencing of 
vectors and associated attributes".
ESRI "Geodatabase" is "a database with a bunch of extra tables defined 
by and understood almost exclusively by ESRI"
ESRI "Coverage" is a "vector topology that covers an area" (ever wonder 
why the OGC Web Coverage Server specification is about delivering 
*raster* data, not vector topologies? because most people have a 
different understanding of the word than us GIS brainwashees).
ESRI "Topology" is a "middleware enforcement of spatial relationship rules"

ESRI rules the intellectual world of GIS people so thoroughly that they 
define the very limits of the possible. Just last week someone told me 
"oh, editing features over the web? the only way to do that is with 
ArcGIS Server". The *only* way, and said with complete certainty. You 
don't want to argue with people like that, it seems almost rude, like 
arguing with people about religion.


P Kishor wrote:
> On 11/16/06, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
>> P Kishor wrote:
>> > Someone asked me recently about open source dynamic segmentation
>> > solutions. I thought, let's ask the PostGIS community. Is this
>> > possible with PostGIS? If not, does anyone know of other open source
>> > solutions for ds?
>> >
>> Can you describe what dynamic segmentation is?
>> What is the algorithm?
>> I guess I can google for it ...
> I don't know the algorithm, but among the many definitions, dynamic
> segmentation allows analysis and mapping of linear features based on
> their positions along a route. Another definition says that it is "the
> process of computing the locations of events on linear features at run
> time based on event tables for which distance measures are available."
> Used in linear reference systems (LRS), typically for roads and
> transportation networks analysis.

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