Line intersecting

[Christian Helring Andersen]

Hi,

I have a table with lines (about 2000). Some of them are crossing
eachother and I would like Mapinfo to select where they are crossing.
How can I do that?

/Christian

[Bill Thoen]

There's a MapBasic function called IntersectNodes() that might help. If you use it to intersect lines or polylines, it returns an one-vertex polyline object with that vertex located where th etwo lines cross. If they don't intersect, it returns a zero-vertex polyline object. The function takes 3 arguments; an object that represents the first line, the object that represents the second line and a qualifier for what you want included in the results. If you use this function interactively, then you have to use the numeric constants listed below:

Define INCL_CROSSINGS    1
Define INCL_COMMON       6
Define INCL_ALL               7


If you don't have to worry about intersections at the end nodes, then I'd recommend you use the INCL_CROSSINGS constant or 1.

Next you perform is a self-intersecting selection of the table that contains your lines and in the attributes list include the IntersectNodes function. Off the top of my head I can't tell you if MapInfo's little database engine can do a self-intersect; I'd have to do a little research first. You might have to do this in stages, but you can research that.

Hope that helps more than confuses!

- Bill Thoen

[Christian Helring Andersen]

Hi Bill,

thanks for the answer - for some odd reason I´m unable to use this
function. MI states that its an unknown command! I´ve searched the net
for some examples on how to use the command but have been unable.
Anyone with an example they would like to share?

Christian

On 31 Aug., 18:42, Bill Thoen <bth...@gisnet.com> wrote:

[Greg Driver]

Christian,

Have you looked at using this tool 'plines_intersections - Identify
all the intersections including the simple junctions between plines
and lines of a table and creates a new table to preserve them' -

http://tinyurl.com/3njxo68

It might be worth giving it a go, but save a copy of your table just
in case!

Regards

Greg.

On Sep 3, 9:49 am, Christian Helring Andersen

> > - Bill Thoen- Hide quoted text -
>
> - Show quoted text -

[Peter Horsbøll Møller]

Christian,

Can you give an example on how you are using it?

Peter Horsbøll Møller
Pitney Bowes Business Insight - MapInfo

2011/9/3 Christian Helring Andersen <christia...@gmail.com>

--
You received this message because you are subscribed to the
Google Groups "MapInfo-L" group.To post a message to this group, send
email to mapi...@googlegroups.com
To unsubscribe from this group, go to:
http://groups.google.com/group/mapinfo-l/subscribe?hl=en
For more options, information and links to MapInfo resources (searching
archives, feature requests, to visit our Wiki, visit the Welcome page at
http://groups.google.com/group/mapinfo-l?hl=en

[Christian Helring Andersen]

Hi Greg,

no go. The program expired 31-12-2006.. Apparently there is no real
version out there. :/

/Christian