Strange map draw issue

[Ed McNierney]

Steve -
 
I actually was asking if the output changed if the SAME map was
refreshed - don't zoom in, out, or pan, just refresh the image/reload
the page.  Does the same image request always return the same image?
 
    - 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 


________________________________

From: Steve Hall [mailto:steve.hall at mercatorgeosystems.co.uk] 
Sent: Thursday, September 14, 2006 10:39 AM
To: Ed McNierney
Cc: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Strange map draw issue


Hi Ed,

Thanks for this.  I may check my label columns in the database for NULLs
and replace them with an empty string ('') instead.   It looks like a
classic 'null' issue doesn't it? 

Yup - zoom in, zoom out, pan etc and the garbage generally just
disappears, or changes its 'content'.   Often the angle is the same
(suspicious) but sometimes not.....  There aren't any features on the
angles so i'm not sure if it's a labelling issue or not.  Plus the
problem only occurs about 1 in 20 or so map draws so is kind of hard to
get a definite problem case. 

Checkout these additional ones :

http://demo.mercatorgeosystems.co.uk/tmp/1158243616324003.png

And just to prove it's not all CA....  ;-)

http://demo.mercatorgeosystems.co.uk/tmp/1158244089248601.png
http://demo.mercatorgeosystems.co.uk/tmp/1158244147717403.png

Thanks Ed,
Steve


Take a 
Ed McNierney wrote: 

	Steve -
	 
	Well, just about anything in California is a little odd.....
	 
	Are you saying that if you simply refresh the image and re-draw
the exact same map you'll see this line of text change?  That's
puzzling.  I would speculate that it's a (garbage) text label for some
garbage feature - there's some feature that's defective in both location
and label (attributes messed up) and that feature is being labeled.
	 
	The first thing I'd try is to eliminate layers from the image,
testing until the garbage goes away.  That could identify the offending
layer; if there are multiple classes in that layer, use the same system
to identify which class it is.  Then see if that says anything helpful.
	 
	    - 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 


________________________________

	From: UMN MapServer Users List
[mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On Behalf Of Steve Hall
	Sent: Thursday, September 14, 2006 9:22 AM
	To: MAPSERVER-USERS at LISTS.UMN.EDU
	Subject: [UMN_MAPSERVER-USERS] Strange map draw issue
	
	
	Hi All,
	
	I've been using Mapserver for a while now, in a variety of
situations, but am seeing a slightly strange behaviour in one of my
setups.  Basically i'm getting a line of 'garbage' being drawn across
the generated map image.
	
	A sample of what I mean is here :
	
	http://demo.mercatorgeosystems.co.uk/tmp/1158239461914994.png
	
	There is no road feature or other line that should be there, and
if I redraw the map the line of garbage will either disappear or change
in either length or 'content'.  It doesn't appear all the time, but
certainly enough to be annoying.
	
	My MapServer version is 4.8.1, running with Apache 1.3.31 on
Fedora Core 4.  I've got several other MapServer based configurations on
this setup and they're all working fine.   The data source in question
is an Oracle 10g (10.1) database which is also used for other systems
and seems fine.....
	
	Weird eh?  Any suggestions much appreciated!
	
	Thanks,
	Steve H
	
	
	  



-- 
Steve Hall
Technical Consultant
Mercator GeoSystems Ltd

Tel (UK) : +44 (0) 114 235 3409
Tel (US) : +1 (562) 735 3541
Fax      : +44 (0) 114 235 3409
Mobile   : +44 (0) 771 828 6323
Email    : steve.hall at mercatorgeosystems.com
Web      : www.mercatorgeosystems.com
Skype    : mercatorgeosystems


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