Strange behavior ....

[Doyon, Jean-Francois]

Oh yeah, the base layers all show up the just fine (the ones in lcc).

That's a good idea, I'll try a few things with the ocmmand line version of
proj see what happens,
although I'm even less of a projection specialist than any of you, since I'm
actually an IT guy
at heart :)

J.F.

> ----------
> From: 	Stephen Lime[SMTP:steve.lime at dnr.state.mn.us]
> Sent: 	Wednesday, September 13, 2000 3:08 PM
> To: 	Jean-Francois.Doyon at CCRS.NRCan.gc.ca; danmo at videotron.ca
> Cc: 	mapserver-users at lists.gis.umn.edu
> Subject: 	Re: Strange behavior ....
> 
> I'm not a projection expert. One could certainly test PROJ behavior at
> extremes outside the mapserver using the utlities included in the PROJ
> distribution. Could also be some data precision/rounding issues at 
> extremes. All cordinates in MapServer are doubles. Could also be
> limitations in the base projection, or at least how it's implemented in
> proj? The base data appears to draw ok though, correct?
> 
> Steve
> 
> Stephen Lime
> Internet Applications Analyst
> 
> Minnesota DNR
> 500 Lafayette Road
> St. Paul, MN 55155
> 651-297-2937
> 
> >>> Daniel Morissette <danmo at videotron.ca> 09/13/00 01:49PM >>>
> JF,
> 
> We have an application that does something similar to yours: we display
> a layer of points in LAT/LON on top of a base map in LCC and we noticed
> the same thing as you.  We haven't investigated the problem yet,
> though...
> 
> Steve, are you aware of any PROJ.4 limitations that could explain that
> behavior?  It seems to be that LAT/LON points located north of a
> specific latitude are lost.  And the latitude at which points starts to
> disappear changes depending on the scale of the map: as you zoom in, the
> line where points start to disappear moves north.
> 
> Any idea?
> 
> Daniel
> 
> "Doyon, Jean-Francois" wrote:
> > 
> > Hello !
> > 
> > Well, things are oging pretty well, but now I've run accross a strange
> > behavior
> > I was hoping someone could explain ...
> > 
> > When I map my search results (using php-mapscript as allways), I create
> > atemporary shapefile.
> > This shapefile use geographical coordinates, whereas the rest of the
> data
> > used to generate the
> > map uses a different projection (lcc to be exact).
> > 
> > Now for some reason, results don't seem to show up in the far north
> > (Nunavut) !
> > Actually, they do show up, but only once I zoom in ! Now, I am *NOT*
> doing
> > anything to that layer
> > that might do this, the layer is "ON" by default, and that's it. All the
> > Other symbols show up.
> > Actually results in Iqualuit show, but not other smaller Nunavut
> communities
> > ... Until I zoom in.
> > 
> > I'm wondering why this might be, and how to fix it ... I'm guessing the
> > projection conversion might
> > have something to do with it ? But that's out of my area of expertise
> ...
> > 
> > Any ideas ?
> > 
> > Thanks,
> > 
> > Jean-Francois Doyon
> > Internet Service Development and Systems Support
> > GeoAccess Division
> > Natural Resources Canada
> > (613) 992-4902
> 
> -- 
> ------------------------------------------------------------
>  Daniel Morissette                       danmo at videotron.ca 
>               http://pages.infinit.net/danmo/ 
> ------------------------------------------------------------
>   Don't put for tomorrow what you can do today, because if 
>       you enjoy it today you can do it again tomorrow.
>