[mapserver-users] Curved Lines

[Mr. Puneet Kishor]

On Jun 27, 2012, at 2:13 AM, juliap wrote:

> Hi all,
> 
> I have the following layer of type line :
> 
> LAYER 
> 	NAME line
> 	STATUS ON
> 	TYPE LINE
> 	CONNECTIONTYPE OGR	
> 	CONNECTION "MSSQL:server=server;database=database;uid=id;pwd=pwd" 
> 	DATA "SELECT geometry::STLineFromText('LINESTRING ('
> 		  +CAST(Geo.STX AS VARCHAR(54))
> 		  +' '
> 	          +CAST(Geo.STY AS VARCHAR(54))
> 		  +', '
> 		  +CAST(Geo.STX AS VARCHAR(54))
> 		  +' '
> 		  +CAST(Geo.STY AS VARCHAR(54)) 
> 		  +')'	  
> 		  ,4326)
> 	FROM column WHERE DATEDIFF(mi, CreatedON, CURRENT_TIMESTAMP) <='%x%'"		
> 	CLASS
> 	STYLE					
> 			WIDTH 3
> 			SIZE 1
> 			COLOR 0 0 128
> 	END # end of style
> 	END # end of class
> 	PROJECTION
> 		"init=epsg:4326" 
> 	END # end of projection
> END # end of layer
> 
> I was wondering how to get a curved line from this data. I tried using angle
> and gap, but I don't see any changes.
> Any suggestions?
> 


Your understanding of geometry is a bit off here. In a query result set, each row is a feature, and a line feature would be made up of two or points; a curved line feature, of course, would be made up of three or more points.

What you are getting in the result set above is a bunch of features, each of which are a point repeated twice. I think what you really want is to create a single line feature from all these points. So, you would probably do some kind of an aggregate on these points. I don't know the functions available in SQL Server, but there must be an analog for Postgres's aggregate functions. You want to collect all the points and make a line feature from them, and then pass that to MapServer to draw. You could make a view that does all this, and then call the view from MapServer.

Hope this helps.


--
Puneet Kishor