[mapserver-users] disappearing point features in North America

[Chris Green]

Hi Jerl

 

Eurueka! "+over" did it!

 

 

Thanks, I owe you one.

 

 

Chris 

 

From: jerl.simpson at craniumjuice.com [mailto:jerl.simpson at craniumjuice.com]
On Behalf Of forums
Sent: 01 February 2012 13:17
To: Chris Green
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] disappearing point features in North America

 

Chris:

 

I had a similar issue, it was suggested to me to add "+over" to my epsg
definitions file.

 

Mine now looks like:

<4326> +proj=longlat +ellps=WGS84 +datum=WGS84 +over +no_defs  <>

<900913> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0
+y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +over +no_defs <>

That seemed to make a difference, but I also upgraded PROJ4 at the same
time.


Jerl

On Wed, Feb 1, 2012 at 5:38 AM, Chris Green <chris.green at ibstv.co.uk> wrote:

I have a problem that may be down to OpenLayers or to Mapserver, or (just as
likely) to me. Basically I am using OL to request WMS maps from Mapserver,
and the map consists of point features with a global spread, typically
around 100 points in each map. The points are defined in a table which has
lat/lon in decimal degrees, and these are converted to 900913 by Mapserver
where my mapfile has an overall projection of epsg: 900913 but the points
layer has projection epsg: 4326.

 

The map is defined in OL with extents: -20037508.34, -20037508.34,
20037508.34, 20037508.34 and the mapfile has the same extents applied.

This all works fine when a map is first displayed, all of the points are
present on the map. However when I scroll the map left or right there is a
'dead spot' where  all the points in North America disappear and then
re-appear, either side of the dead spot. Looking with Firebug at the
bounding box that OL uses to request the map from Mapserver I can see that
the points disappear when the bounding box is between left bounds of about
-23700000 and -33700000. Only the points in North America are affected,
never those in Europe or Asia. 

 

I have been wrestling with this for quite a while, experimenting with
extents etc, all without any effect.  Does anyone recognise where my problem
may lie, or else have any suggestions how to diagnose what is going on?

 

 

Chris  

 

 

 

 


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