[postgis-users] Shifting linestrings left

[Ben Madin]

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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