Increase Clarity of WMS

[Ed McNierney]

Kyle -

Well, if you increase the WIDTH and HEIGHT to 512 it will certainly look
better - and larger!

You are taking a relatively large image and asking MapServer to shrink
it down for you for display.  I haven't time to decipher all the
JavaScript in there, but I suspect your "simply chopping up tiles using
ImageMagick" example is actually generating HTML that tells the client
browser to stuff an oversized PNG into a smaller IMG tag.  Your
individual image tiles (from the floorplans/tiles/ directory) are
actually much larger images than your
http://maps.kylemulka.com/imagemagick/livedude.php displays.  Each
individual tile is 512x512 pixels, but your final output image is much
smaller than that.

As a result, the quality of the output image may depend heavily on the
browser being used.  I think those 512x512 tiles are being displayed in
IMG tags with HEIGHT and WIDTH properties set to a smaller value.  The
browser then squishes the images into the IMG space available.

The image you're using is almost a worst-case scenario for MapServer.
It's essentially a vector drawing that's been scanned as a raster image.
You've got lots of thin lines that easily appear and disappear at
different scale levels, depending on how the image is resampled.

If you're going to use scanned line art in MapServer, you'll get the
best results by producing high-quality resampled versions (ImageMagick
is fine) at each specific scale/zoom level you'll want to use.  Then
force the user to only use one of your preselected zoom levels.  Make
sure that each image - when displayed - ends up exactly the same size as
the original image on your server.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242 

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Kyle Mulka
Sent: Monday, April 03, 2006 7:30 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Increase Clarity of WMS

Here's one of the WMS tiles I'm using. I've tried stretching it using
different values for the height and width but nothing I've tried has
made it look better or worse.
http://kylemulka.com/cgi-bin/mapserv?map=floorplans.map&REQUEST=GetMap&S
ERVICE=WMS&VERSION=1.1.1&LAYERS=dude-1&STYLES=&BGCOLOR=0xFFFFFF&TRANSPAR
ENT=TRUE&SRS=EPSG:4326&BBOX=-83.7158203125,42.2905166207974,-83.71444702
148438,42.291532494305976&WIDTH=256&HEIGHT=256

-Kyle

Josh Livni wrote:
> Kyle,
> 
> I could be wrong -- I haven't used a mapserver wms in Google Maps - 
> but I think your mapserver image may be being squashed a bit.  It's a 
> bit less wide relative to the height/width of your Imagemagick 
> version. Also the gmap div seems to be a different height/width in the

> different versions.
> 
> WMS will happily respond with the exact extent, but perhaps not the 
> relative height/width you expect, thus 'squashing' the image, which 
> may be causing the image issues you're seeing.
> 
> You may want to play with this by adding a &height &width to the wms 
> query, or you could try playing with the div height/width ratios, and 
> seeing if you get similar results if one is a bit off, as I may be 
> off-base with this theory.
> 
>   -Josh
> 
> Kyle Mulka wrote:
> 
>> I have these very detailed floor plans that I'd like to georeference 
>> and display through mapserver's WMS sever, however, the clarity of 
>> the images degrades when it goes through. How can I increase the 
>> clarity of these floorplans through the WMS?
>>
>> Here's with mapserver:
>> http://maps.kylemulka.com/floorplan-test10.php
>>
>> Here's without (simply chopping up tiles using Imagemagick) 
>> http://maps.kylemulka.com/imagemagick/livedude.php
>>
>> Here's the parts of the map file for just the first floor:
>> MAP
>> NAME "UofM"
>>   FONTSET fontset.txt
>>   PROJECTION
>>       "init=epsg:4326"
>>   END
>> IMAGETYPE png24
>> EXTENT  -83.747063 42.272038 -83.709126 42.297056 SHAPEPATH 
>> "/umdata/"
>> LAYER
>>   NAME "dude-1"
>>   TYPE raster
>>   DATA "dude1.tif"
>>   PROCESSING "RESAMPLE=AVERAGE"
>>   PROCESSING "DITHER=YES"
>>     METADATA
>>       "wms_title" "dude-1"
>>       "wms_onlineresource" 
>> "http://kylemulka.com/cgi-bin/mapserv?map=floorplans.map&"
>>       "wms_srs" "EPSG:4326"
>>   END
>>   STATUS ON
>> END
>> END
>>
>> -Kyle
> 
> 
> 
> 
>