[mapserver-users] setting projection based on zoom

[Tom Kralidis]

Hi,

Does this work with imgext instead of mapext?  I can't seem to get it working with imgext.  Any hints?

Thanks

..Tom

=================================
Tom Kralidis
Systems Scientist
Canada Centre for Remote Sensing
Tel: (613) 947-1828
http://www.ccrs.nrcan.gc.ca
=================================

You wrote...

>Date: Tue, 25 Sep 2001 15:26:01 -0500
>From: Stephen Lime <steve.lime at dnr.state.mn.us>
>To: Hannah.Jensen at erdc.usace.army.mil, mapserver-users at lists.gis.umn.edu
>Subject: RE: [mapserver-users] setting projection based on zoom
>
>Here's why. The extent is projected when it is read from the CGI data, so it is 
>converted using the existing projection information it has at that time. Setting
>the projection afterwords has no effect but to screw things up. This is fixable.
>Hannah, would you be so kind as to add this to bugzilla?
>
>Thanks- Steve
>
>Stephen Lime
>Data & Applications Manager
>
>Minnesota DNR
>500 Lafayette Road
>St. Paul, MN 55155
>651-297-2937
>
>>>> "Jensen, Hannah ERDC-CRREL-NH" <Hannah.Jensen at erdc.usace.army.mil> 09/25/01 03:09PM >>>
> 
>Proof that you should leave your desk once in awhile -- someone down the
>hall saw my post and walked over to give me the answer.  Thanks, Joel!
>
>Anyway, if mapext is specified in lat/long, it works properly.  Only caveat
>is that the projection must be specified FIRST in the URL.  So this works:
>
>http://myserver/cgi-bin/mapserv34g?mode=browse&map=..%2Fhtml%2Fusamap%2Ftige 
>r.map&map_projection=proj=utm,zone=19&mapext=-78.12+40.14+-63.19+49.23
>
>but this doesn't:
>
>http://myserver/cgi-bin/mapserv34g?mode=browse&map=..%2Fhtml%2Fusamap%2Ftige 
>r.map&mapext=-78.12+40.14+63.19+49.23&map_projection=proj=utm,zone=19
>
>Strange but true...
>
>
>
>-----Original Message-----
>From: Jensen, Hannah ERDC-CRREL-NH
>To: 'mapserver-users at lists.gis.umn.edu' 
>Sent: 9/25/01 3:17 PM
>Subject: [mapserver-users] setting projection based on zoom
>
> 
>Hi, all.  I would like to be able to change projections based on how far
>the
>user is zoomed in.  For example, if they start out looking at the US in
>Lambert Azimuthal Equal Area but zoom in on Alaska, the map should
>display
>the zoomed in area in UTM zone 6.  I'm hoping to be able to do this with
>CGI
>variables, but maybe that's not possible.  If I pass in the projection
>parameters and the map extent (in the new projection units) like so:
>
>http://myserver/cgi-bin/mapserv34g?map=../html/usamap/tiger.map&mode=bro 
>wse&
>map_projection=proj=utm,zone=6&mapext=415087+7115646+546659+7214763
>
>it works fine.  But since I don't know the map extent in the new
>projection
>before conversion, what variables should I pass to properly define the
>map
>extent?  Can I somehow tell it to calculate the new extent based on the
>old
>one?  Is there a better way to do this?  Thanks in advance for any
>info/advice...
>
>
>
>Cheers,
>Hannah
>