[postgis-users] Shifting linestrings left

[Simon Greener]

Ben,
See Regina Obe's upgis_lineshift
http://trac.osgeo.org/postgis/wiki/UsersWikiplpgsqlfunctions
I have a PostGIS version, without the curves, of this one:
http://www.spatialdbadvisor.com/oracle_spatial_tips_tricks/97/implementing-a-move-parallel-function-for-sdo_geometry-linestring-data-in-oracle
If you want the code, email me privately as I have not yet blogged on it.
Simon
On Thu, 23 Dec 2010 14:56:49 +1100, Ben Madin <lists at remoteinformation.com.au> wrote:

> Thanks Brent,
>
> Happy Christmas / New Year to you as well!
>
> On 23/12/2010, at 2:07 PM, pcreso at pcreso.com wrote:
>
>> ST_Translate() is the simplest, but if your lines are horizontal you may want a Y shift as well?
>>
>> http://postgis.refractions.net/documentation/manual-svn/ST_Translate.html
>
> Lines are roads, so they go every which way.
>
>> Having done this, I suggest you also use ST_reverse() to reflect the direction is now going the other way (unless it already is :-)
>> http://postgis.refractions.net/documentation/manual-svn/ST_Reverse.html
>>
>> For more complex shifting of features, probably overkill in your case, see
>> http://postgis.refractions.net/documentation/manual-svn/ST_Affine.html
>
> This might be what I am after, but I was thinking of somehow translating each segment parallel to it's current alignment and then rejoining with a nice smooth curve... kind of like a 1-sided buffer.
>
> cheers
>
> Ben
>
>
>
>
>
>> --- On Thu, 12/23/10, Ben Madin <lists at remoteinformation.com.au> wrote:
>>
>> From: Ben Madin <lists at remoteinformation.com.au>
>> Subject: [postgis-users] Shifting linestrings left
>> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>> Date: Thursday, December 23, 2010, 3:13 PM
>>
>> G'day all,
>>
>> I have a problem where I am trying to show the route of livestock movements, but I am loosing information when the travel along the same road in different directions (ie in some cases they travel from a saleyard to a feedlot, then back to the saleyard after a period). The roads they travel along are single linestrings.
>>
>> Is there a way to 'shift' the linestring to the left - after all, that would be sensible side of the road to drive on...
>>
>> cheers
>>
>> Ben
>>
>>
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