[postgis-users] line from points (& feature manipulation/editing)

[Wood Brent]

--- strk at refractions.net wrote:

> > 
> > how I can to create a line or polyline  from a collection of points with
> > coordinates, inside of postgis of course
> 
> This is an unavailable feature, being discussed.
> How would you specify the ordering of the composing points ?

Summat I'm also interested in, improved feature editing & manipulation in
PostGIS, building lines from points, assembling polygons from lines, merging
polygons by removing shared borders, splitting polygons by inserting a new
line, etc....

At present, I believe GRASS 5.7 is perhaps the best tool for this? JUMP/JTS is
also there, but doesn't do what I need. QGIS may get there, it is certainly
adding functionality quite rapidly. 

Is there a way to have PostGIS use something like the JTS natively, much as it
uses GEOS now, to implement such capabilities?

But to specify the line vertex order from point features, you would need some
attribute(s) to provide an explicit order. In many cases I work with, this
could be a timestamp, to turn a set of stations into a track.

ie: something like 

select linefrompoint(the_geom) where <...> order by <ordering_attr(s)>

to create a line from a set of points selected & ordered from a table of
points.
(unless I'm missing something...) 



& I second the thanks for both PostGIS itself & the help from this forum!!


Cheers,

  Brent Wood