[postgis-users] depict a polygon using cross hatching

[George Silva]

Hello Mike,

What kinda of software will be used to do this?

Most GIS softwares can depict line hatchings without needing it physically
exists on the database. Each line of the hatch has a special meaning for you
or no?

If so, you should consider using a proper style, that will do that without
giving you headaches to create the hatches.

George

On Fri, Jun 3, 2011 at 3:17 PM, Michael Welter <mike at introspect.com> wrote:

> Hello,
>
> I have a polygon (with interior holes) that I would like to depict on a map
> using diagonal lines.  I don't suppose there's a ST_ function for this  :-)
>
> Thinking out loud, I should derive the bounding box of the polygon, divide
> the top and right edges into equidistant points.  From the top points draw
> 135° vectors, and from the right points draw 225° vectors to the other side
> of the box.
>
> Now the hard part:  for each line, determine the point where it enters the
> polygon and the point where it exits.  Also, where it enters an interior
> hole and where it exits.
>
> The actual drawing on the map happens on a client computer (without
> postGIS), so the desired result from postGIS would be a list of line
> segments.
>
> Does anyone have any ideas on this?
>
> Thanks,
> Mike
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-- 
George R. C. Silva

Desenvolvimento em GIS
http://geoprocessamento.net
http://blog.geoprocessamento.net
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