RE: [MI-L] Creating a line from a series of points

Peter Horsbøll Møller Thu, 22 Jun 2006 00:06:33 -0700

If you know for sure that the points that should be connected, you could connect every point to all the other points, and afterwards delete the records that not are 1 km long.

Like this:

1. Add an ID and a JOIN column to your table. Both Integer

2. Update the ID column with ROWID

3. Update the JOIN column with 1

4. Make a copy of your table and open this copy as well.

5. Create a join of the two tables:

Select ID, CentroidX(TABLE1.OBJ) "X1", CentroidY(TABLE1.OBJ) "Y1", CentroidX(TABLE2.OBJ) "X2", CentroidY(TABLE2.OBJ) "Y2"

From TABLE1, TABLE2

Where TABLE1.JOIN = TABLE2.JOIN

And TABLE1.ID <> TABLE2.ID

And Distance(CentroidX(TABLE1.OBJ), CentroidY(TABLE1.OBJ), CentroidX(TABLE2.OBJ), CentroidY(TABLE2.OBJ), "k") between 900 and 1100

6. Save the result as a base table and open it

7. Update the OBJ of the result with CreateLine(X1, Y1, X2, Y2)

Note that I have said the distance between the points should be between 900 and 100 meters. You can of course make this smaller, like 990 and 1010

You could do most of it using the MapBasic window. wite these lines and hit Enter at the end of each, except the SQL where you need to write all lines, mark them and hit Enter

Alter Table TABLE1 (Add ID Integer, Join Integer)

Update TABLE1 Set ID = ROWID, JOIN = 1

'Manualle make a copy and open it

Select ID, CentroidX(TABLE1.OBJ) "X1", CentroidY(TABLE1.OBJ) "Y1", CentroidX(TABLE2.OBJ) "X2", CentroidY(TABLE2.OBJ) "Y2"

From TABLE1, TABLE2

Where TABLE1.JOIN = TABLE2.JOIN

And TABLE1.ID <> TABLE2.ID

And Distance(CentroidX(TABLE1.OBJ), CentroidY(TABLE1.OBJ), CentroidX(TABLE2.OBJ), CentroidY(TABLE2.OBJ), "k") between 900 and 1100

Into RESULT NoSelect

'Manualle save the table RESULT to disk and open it

Update RESULT Set OBJ = CreateLine(X1, Y1, X2, Y2)

HTH,

Peter Horsbøll Møller
GIS Developer, MTM
Geographical Information & IT

COWI A/S
Odensevej 95
DK-5260 Odense S.
Denmark

Tel     +45 6311 4900
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From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Uffe Kousgaard
Sent: Thursday, June 22, 2006 7:40 AM
To: Mapinfo-L
Subject: Re: [MI-L] Creating a line from a series of points

Hi Alan,

If your points are completely unordered and you don't know the order, it sounds as if you need to apply a travelling salesman algorithm to determine the best order.

Kind regards

Uffe Kousgaard
www.routeware.dk

----- Original Message -----

From: Alan Silvester

To: [email protected]

Sent: Wednesday, June 21, 2006 5:30 PM

Subject: [MI-L] Creating a line from a series of points

Dear All,

Does anybody know how to automatically create a line from a series of points, i.e. rather than drawing a line from point to point, I want to be able to make a line that automatically joins up the points. The problem is, is that the next point to join up with the line may not be the next record in the table?! The points are however all 1km apart.

Does anyone have any ideas?

Regards,

Alan

Alan Silvester

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