POLYGONS AT INTERNATIONAL DATE TIME BOUNDARY

[Efren Serra]

Folks,

I was wondering how mapserver handles polygons at the international
date-time boundary.  Any help would be 
Appreciated.

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Stephen Woodbridge
Sent: Wednesday, August 22, 2007 8:32 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Showing Movement Direction


Ben,

This is the same problem of displaying GPS tracks. They explicitly a set 
of points, but when taken as a track over time they are a polyline. You 
can not do anything with mapserver directly. You do have a few options:

1) write a script that adds heading column to each point, based on the 
previous point and use this angle to orient a marker for the point.
2) load the data into postGIS and convert the points to a polyline and 
either display it from postGIS or dump it back to a shapefile.
3) use postGIS to compute the heading column
4) other similar preprocess the data options

try search for "gps track" in both mapserver archives and postgis archives.

-Steve W

Ben Madin wrote:
> G'day all,
> 
> I have been looking and reading, but I'm not sure I'm looking for the
> right thing.
> 
> I have a number of points from satellite based tracking, giving me a
> list of longitude, latitude and a timestamp. These are fairly regular, 
> and although I can display the points on the map window and see where 
> animals have moved to, I can't tell which way they moved just by 
> looking. We vets need to know what came first...
> 
> So I thought I could convert adjacent points (temporally) into line
> segments, (earliest point first, latter point last), but I can't find 
> anywhere in Mapserver that seem to explicitly explain how to do this (or 
> whether it can be done). 
> 
> Can anyone either :
> 
> direct me to the right place, or
> give me a set of keywords which might get me to the right place, or
> advise me to give up for now?
> 
> cheers
> 
> Ben
> 
> 
> --
> 
> Ben Madin
> REMOTE INFORMATION
> 
> t : +61 8 9192 5455
> f : +61 8 9192 5535
> m : 0448 887 220
> Broome   WA   6725
> 
> ben at remoteinformation.com.au <mailto:ben at remoteinformation.com.au>
> 
> 
> 
> 
> 
> Out here, it pays to know...
> 
> 
> 
> 
> 
> 
> 
> 
>