This is really a great forum!
I never heard of the possibility to use closed object as a target during
voronoi polygonisation, I actually use older MapBasic and implement newer
statements through <Run Command>.
Thanks especially to Peter and Ian who pointed me to the right direction.
Jaromir
On Wed, 17 May 2006 22:01:59 +0200, Peter Horsbøll Møller <[EMAIL PROTECTED]>
wrote:
Hi,
Just a short comment: remember that the Voronoi function in MapInfo
actual can use a closed object, set as target, as clipping/extension
area.
So if you manually or thru code, start by making a layer editable,
selects an closed object from this layer, and then selects the points to
use for voronoi creating, MapInfo will make sure that the "inside" of
the target area is filled with the voronoi objects.
This is a neat and often overlooked feature, that also is well describes
in the manual ;-)
Peter Horsbøll Møller
GIS Developer, MTM
Geographical Information & IT
COWI A/S
Odensevej 95
DK-5260 Odense S.
Denmark
Tel +45 6311 4900
Direct +45 6311 4908
Mob +45 5156 1045
Fax +45 6311 4949
E-mail [EMAIL PROTECTED]
http://www.cowi.dk/gis
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Nabors,
Steve
Sent: Wednesday, May 17, 2006 3:47 PM
To: Uffe Kousgaard
Cc: [email protected]
Subject: RE: [MI-L] Voronoi
I agree with Uffe,
Looking at the points, you have an idea, but you never really know how
big and what rotation the voronoi MBR will be. So if the voronoi MBR is
"clipping" areas that you want included then you simply need include
more existing points beyond the area of interest. If you don't have any
more points outside the are of interest, simply put some new points well
outside your area of interest and include them in your selection.
So the rule of thumb is, always include points well ouside of the area
of interest or create dummy/dataless records to allow you to do the same.
A classic example would be land based points near the ocean and part of
the coast line gets "clipped" because there are no points out in the
ocean to increase the vornoi MBR. Voronoi creates "grains of growth" or
polygons that are the result of a bisection or half the distance from
any one point, to another. In the ocean problem, simply put some
dataless points out in the ocean, so that at least half the distance
between any ocean points and land points is still out over the water.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Uffe
Kousgaard
Sent: Wednesday, May 17, 2006 4:52 AM
To: Mapinfo-L
Subject: Re: [MI-L] Voronoi
Just add some additional points far away from your own points and then
clip the resulting polygons with whatever you had in mind for additional
distance.
Kind regards
Uffe Kousgaard
www.routeware.dk
----- Original Message -----
From: "Jaromir Svasta" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, May 17, 2006 10:51 AM
Subject: [MI-L] Voronoi
Hi listers,
Does anyone of you have some nice code (MB or VB) for creating voronoi
polygons from points? <Create Object As Voronoi> stetement in MapBasic
is
not sufficient for my purpose, because it limits the outer boundary of
polygons to the point's MBR, I need to extend it some distance.
--
Jaromir SVASTA
Hydrogeologist
Geological Survey of Slovak Republic
Mlynska dolina 1
817 04 Bratislava
Slovak Republic
Tel: +421 2 59375326
Mobile: +421 908783589
Fax: +421 2 54771940
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