[ka-Map-users] Re: Desperate with a blank page

Steve Walker walker at mfgis.com
Wed Apr 18 13:15:15 EDT 2007

Here are some of the things you can do to try to track down your problem
(dislaimer:  I am not a developer or a guru, just a regular user who has
had to debug my own Ka-Map! applications)

Review, if you haven't, this page on the Ka-Map Wiki:
http://ka-map.ominiverdi.org/wiki/index.php/Troubleshooting.  It's a start
but could use much more detail.  Perhaps this thread can help fill in some
of that detail.

First, ensure mapserver is properly working on your system.
Try http://yoursite/cgi-bin/mapserv (may vary depending on your local site).
If it returns:

No query information to decode. QUERY_STRING is set, but empty.

Then mapserver is nominaly setup ok.

Next, try rendering a map using Mapserver's shp2img command line utility:
shp2img -m /var/www/us/map/kamap.map -o /tmp/test.png

Is an image created?  If so, Mapserver is working.

Now, turn your attention to Ka-Map

View the init file in your browser:  http://yoursite/init.php
You want to see something which looks like this:

map = new _map({name:'USMapServer',title:'USMapServer',currentScale:
_layer( {
= 72;this.addMap( map );this.tileWidth=256;this.tileHeight=256;this.server
= 'http://amboro.usmapserver.com';this.tileURL =

If so, your php configuration is probably OK.
If not, you will receive some time of error message which may help you to
track down your problem.

Next, you can use some of the tools in Firefox to help debug your problem:

Open Firefox's Error Console:   (Tools/Firefox) and re-load your page. 
You're looking for references to any of Ka-Map's javascript files.  I
can't help with the specifics of any errors, but they may give you insight
to the source of your problems.   You can ignore any errors associated
with any CSS files.

Also in Firefox, use the 'Media' tab under 'Page Info' (Tools/Page
Info/Media).   What you will see is a separate line-info item for each
element on your page (CSS files, images, etc.)  Most important will be the
URL references to each map image element on your Ka-Map canvas.  A
functioning Ka-Map will have multiple entries which look like this:

   (all on one line)

   (all on one line)

And each one will show an image of the specific tile's content.

If Ka-Map is broken, you may see these URL references but the picture will
be blank and have dimensions of 0 by 0 pixels.  This to me has often meant
configuration problems back in the Mapserver .map file, or PostGIS issues
(projections, permissions, etc.)

If you see none of these tile URL references at all, this may indicate a
different set configuration problems (I haven't encountered this so I
can't help you).

Well, those are the tricks I have learned.  I am sure they are far from


> I a newbie in kamap. I've kamap installed on ubuntu, and I believed that
> it's well installed. My problem is that when I put the URL on the browser
> I
> obtain a blank page with "ka-Map!" on the title bar of the browser. I've
> try
> hundreds of configurationson httpd.con, config.php,... but the result is
> the
> same. What can I do to resolv this problem?
> Thanks in advance
> End of ka-Map-users Digest, Vol 24, Issue 17
> ********************************************

Steve Walker
Middle Fork Geographic Information Services
walker at mfgis.com

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