[mapserver-users] converting line object to series of points

[Mark Brooks]

Thanks for your insights and help.

The lines I'm working with will have multiple points.  They are 
hurricane tracks.  The tracks are made of points, about 3-12 hours 
apart.  Therefore, sometimes the points are close and other times very 
far away from each other.  I can easily connect the track points to 
create a line.  But I need the points in between each observation so 
that I can determine what county landfall occurs.  The y=mx+b method 
will work, but I was hoping there may be an easier to do it.  Or perhaps 
I'm making the problem too complicated to begin with??

Mark


Bob Basques wrote:
> All,
> 
> 
> If you don't care about the actual coordinates of the points along the 
> line (just trying to display things) I wonder if a linetype/combined 
> with a scaling option would get you what you are looking for.
> 
> 
> bobb
> 
> 
>  >>> Andy Colson <andy at squeakycode.net> wrote:
> 
> On 4/15/2010 10:51 AM, Mark Brooks wrote:
>  > I'm using PHP Mapscript.  I need a point every X meters along the line.
>  >
>  > Mark
>  >
>  >
>  > Andy Colson wrote:
>  >> On 4/15/2010 10:24 AM, Mark Brooks wrote:
>  >>> I have a line object that I need to to turn into points. How can I
>  >>> create a series of points from the line object?
>  >>>
>  >>> Mark
>  >>> NC State University
>  >>
>  >> A line has many many points. Which are you interested in? Just the
>  >> first and last? Any one point on the line? The mid-point? A point
>  >> every meter along the line? The closes point on the line to some other
>  >> object?
>  >>
>  >> I know of two options:
>  >> 1) use PostGIS:
>  >> select st_centroid(the_geom) from layer
>  >>
>  >> 2) use mapscript
>  >>
>  >>
>  >> -Andy
>  >
> 
> Does the line have a single start and end point?  (a MULTILINE record
> can have multiple lines (so multiple start and end points, all stuck
> togethor).
> 
> In general, find the start and end points, use them to find the equation
> of the line (y=mx+b if I recall correctly), then use that equation to
> find one corrd based on another.  (so, plug in a buch of x's to find
> their y's).
> 
> -Andy