[Manifold-l] Points to Lines - v 7x

[Henry Holland]

Assuming you have a Table component in Manifold which contains your
points, if you go Import/Drawing, then This Project(), on the Import
Data dialog at the bottom you can select the Line ID, which is the
'Group By' column for the query. Once you've selected a column to group
by, the Coordinate Order field on the dialog activates and you can
select the node order ('Order By' column for the query). 
 
I'll try and explain how and why it works the way it does (or my
understanding of it). If you have a set of points that you want to turn
into lines (or one line in your case), you are aggregating (collecting)
those points into lines. Each line consists of a set of points (nodes).
The Import function needs to know which points belong to which lines,
hence the Group By/Line ID column. The Order By clause is needed so you
don't get spaghetti lines going all over the place (unless that is how
you walked the line with the GPS ;-). 
 
Hope that makes sense.
 
Henry
ps. The projection thing is a different matter. I have so far been
limited to using lat/long points so it has worked fine for me.
 
__________________
www.mapthis.co.za <http://www.mapthis.co.za/> 

-----Original Message-----
From: manifold-l-bounces at lists.directionsmag.com
[mailto:manifold-l-bounces at lists.directionsmag.com] On Behalf Of
Springfield Harrison
Sent: 15 September 2006 09:23 AM
To: manifold-l at lists.directionsmag.com
Subject: Re: [Manifold-l] Points to Lines - v 7x


Hello James:

        This looks promising but fails (?), not sure why.

        I tried Linking the table, the Import option doesn't offer the
create line function (why?).  I have a Point Order field but don't
understand the need for "Grouping".  Several queries were created, I
think the process changed the Projection (?).

        From one of the query components I extracted the Query that
apparently powers the whole operation.  I commented out the Option line
that changed the Projection, deleted the Group By parameter, ran the
query and got a single field, single record table:

                        GeomData <geom, line, branches: 1, coords: 6430>

        I tried copying and pasting this as a drawing but those options
are everywhere grayed out.  It looks like it could be a line with 6430
nodes.  My XLS table has NAD83 UTM coordinates.

        There is no useful Help for the ConvertToLine syntax or the Link
Table "Make Line" feature or I could likely make this work based on your
suggestion.  Is this stuff documented elsewhere?

        Sorry to pester you with this but Help seems to be silent where
it is needed most.  I have just installed 7x plus update.



At 14/09/2006 08:20 PM Thursday, JBurn_GIS wrote:



Make sure that you have a table w/ your point coordinates, a "grouping"
column (a default "0" field will do) and a field with the point order.
Import a drawing from your table - you will then have the option to
create a line from the points.  Make the line id your "grouping" field,
and use your order field for the order.  You should now get your line.
Unlink it and perform your simplify to your desired precision.
 
Cheers.
---------------
James Burn BSc, GIS(pg), AScT


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


From: Springfield Harrison <mailto:stellargps at shaw.ca>  


To: manifold-l at lists.directionsmag.com 


Sent: Thursday, September 14, 2006 8:24 PM


Subject: [Manifold-l] Points to Lines - v 6.5



Hello All:



        I have 6400+ points, 20 m apart that I need to join into a line.
Can't find a Transform or Overlay command that seems to apply although
I'm sure it's there somewhere.



        Also, I need to thin/weed/decimate the resulting line into far
fewer points.  I think Simplify will work but I need the line first (?).
Any thoughts here, also?



                Many TIA, cheers . . . . .



                           -= Springfield Harrison, B. Sc., Stellar GPS
& Mapping =-


                                             -= Sidney, B. C. Canada =-



                                                   www.StellarGPS.ca
<http://www.stellargps.ca/> 







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                                     -= Stellar GPS & Mapping =-
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