[mapguide-internals] RE: changing mapguide's image type

Andy Morsell amorsell at spatialgis.com
Mon Mar 5 12:48:59 EST 2007


OK, that sounds reasonable.  So, for most cases with imagery, we will setup
our image layers as basemap tile layers using JPG and then the overlays as
PNG.  That should work nicely.  I hope the basemap tile edge artifact issue
will also be fixed around he same time that the RFC is implemented.

I would still like to have an author configurable parameter on a map by map
basis (not web layout as I said before).  This way, if not using basemap
layers, the author can dictate whether the rendered image will be JPG or
PNG.


Andy 

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Trevor
Wekel
Sent: Monday, March 05, 2007 9:43 AM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] RE: changing mapguide's image type

Hi Andy,

The PNG/JPG paramter will be added for tiles in RFC 13.  Adding a global
configuration parameter for the overlay is problematic for the reasons you
give below.  The overlay has to be PNG if you want transparency but PNG is
an expensive format for raster imagery.  For raster imagery on a base map, a
JPG tile with PNG overlay should be more effective.  This will be supported
by RFC 13.

Thanks,
Trevor

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Andy
Morsell
Sent: Monday, March 05, 2007 10:13 AM
To: mapguide-internals at lists.osgeo.org
Subject: [mapguide-internals] RE: changing mapguide's image type


Trevor,
Are you going to be adding this configuration parameter in RFC 13?  I would
also like to see this be a user config parameter for normal AJAX viewer map
renderings.  This would probably be outside the context of this RFC,
however.  In the sites that I have manually changed this setting in
ajaxmappane.templ, the performance increase has been profound.  I'm afraid
that the default format of PNG, while visually nicer, is causing many sites
to appear much slower than they could be if using JPG.  This is mostly
apparent in cases where the map has imagery layers and PNG transparency has
no advantage.  For instance, a site I just made this switch to, Kids GIS, a
standard AJAX map request resulted in a map image of about 1 MB in size
whereas changing it to JPG results in about 75 KB images.  This has greatly
improved the client experience
- but again, does not look quite as nice.

Ideally this parameter would be configurable on a web layout by web layout
basis and not be global site parameter, as it is now.

Thanks for considering this.

Andy



Trevor Wekel wrote:
> 
> Hi Paul,
> 
> Not currently.  It's a hardcoded parameter.  I may be able to add this

> to RFC 13 but it would be a global parameter for the Site Server.  
> Would you also want control over the JPG compressibility?
> 
> Thanks,
> Trevor
> 
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Paul 
> Spencer (External)
> Sent: Monday, February 05, 2007 10:25 AM
> To: MapGuide Internals Mail List
> Subject: [mapguide-internals] changing mapguide's image type
> 
> Hi,
> 
> is it possible to change the image type used by mapguide from PNG to 
> JPG?  I thought I saw this option in the system administration tool at

> one point but now I can't find it.
> 
> Also, is it possible to use different image types?  I have a client 
> who wants to use tiles and cache imagery as jpg because png is too 
> big, but png is better for the rest of the app.
> 
> Cheers
> 
> Paul
> 
> +-----------------------------------------------------------------+
> |Paul Spencer                          pspencer at dmsolutions.ca    |
> +-----------------------------------------------------------------+
> |Chief Technology Officer                                         |
> |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
> +-----------------------------------------------------------------+
> 
> 
> 
> 
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