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
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Out here, it pays to know...
