Robert,
The main problem when using Enclose is that you might have places where
you line work hasn't been snapped correctly. The Enclose funktion will then
ignore this region as it doesn't support any tolerance
setting.
To improve the result I would recommen that you do one of two
things:
1. Use the Objects Snap statement to snap node points
together.
Objects Snap From tablename [Tolerance [Node node_distance]
[Vector vector_distance] [Units unit_string] [Thin [Bend
bend_distance] [Distance spacing_distance] [Units unit_string]
] [Cull Area cull_area [Units unit_string] ]
]
2. Extend every line with a few inches/cms at the start and end section.
This might make the chance of snapping better.
Of course this solution might also result in a number of small regions in
certain places.
Also remember that when using the Enclose thru MapBasic you can specify
which table to put the result into:
Objects Enclose
Into Table
MYTABLE
This can also be
done thru the interface as MapInfo will insert the regions into the editable
layer.
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
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Data
DirectionsSent: Wednesday, April 19, 2006 2:36 AMTo:
Robert Crossley; mapinfo-l@lists.directionsmag.comSubject: Re: [MI-L]
Enclose function.
Robert,
One "gotcha" is that the Enclose function will
create polygons from your polylines BUT the polylines remain in the table.
You then have to select all polylines, delete them
and pack your table.
Also note that if your line work is not 100% clean
and snapped to nodes, that polyline may be overlooked and you end up with a
larger polygon.
I actually go through the following (labourious)
processes to create polygons from polylines:
1) Digitise all polylines
2) I use Discover's "Auto-Polygonise" function to
clean the line work - identify misclosures that I manually correct.
3) I then save a copy of my polylines to a new
table "Polyline Backup"
4) I run the Enclose function to create polygons as
no fill, single black border. At this stage I DO NOT save the
table.
5) Then I select all polylines from the table and
press delete.
6) I open my polyline backup table and position it
BELOW the polygon table in Layer Control. I set the display override for the
polyline table to red line, double thickness.
7) I then carefully examine the Mapper Window and
note any areas where a polygon may not have been created.
8) If some polygons have been missed, I REVERT the
polygon table, make changes and repeat steps 4 - 7
9) Once satisfied with the outcome, I PACK the
polygon table.
It is probably quite a round-about way of doing
things, but I've found this gives me the best result.
Regards,
Bill
===
- Original Message -
From:
Robert
Crossley
To: mapinfo-l@lists.directionsmag.com
Sent: Wednesday, April 19, 2006 8:08
AM
Subject: [MI-L] Enclose function.
Hi all,
Ive just discovered the enclose command to create
polygons from a network of lines. Its actually a very neat polygon
building tool.
I intend to implement it into a mapbasic program
instead of a tool that I developed that splits a polygon with an intersecting
line (the tool that does that in MapBasic doesnt work very
well).
So, Has anyone any gotchas for this command before I
go down that way?
The enclose command will create polygons from
concentric circles, which the other tool wont so that is an advantage for me
anyway.
I remember that I had to put a 200 millisecond wait
into the split function to stop it crashing in Mapbasic when selecting the
resultant objects to delete.
BTW, is the accuracy of an object variable determined
by the current coordinate system?
R
---
Robert
Crossley
Agtrix
P/L Australia
Far
Southern Queensland
Office:
9 Short
Street
PO
Box
63
New
Brighton
2483
P: 61 2 6680
1309
F: 61 2 6680
5214
E: [EMAIL PROTECTED]
W: www.agtrix.com
Brisbane
Office:
109 Milsom
St
Cooparoo
4151
Queensland
P: 61 7 3843
3363
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