[Chameleon] tiff hang

Ken-ichi kueda at wso.williams.edu
Tue Dec 7 17:02:56 EST 2004

Thanks Paul.  I tried loading drawmap.php directly, and that usually 
renders the map even when the Chameleon app hangs (though sometimes it 
hangs too), so I guess drawmap.php may not actually be the culprit.  I 
made another, minimal app with just the ZoomIn, ZoomOut, Recenter, and 
MapDHTML widgets, and it still hangs on the tiffs, so I don't think it's 
any of my custom widgets that are mucking things up either.

I am really at a loss here.  The strangest thing about this is that if I 
convert the TIFF to an Erdas Imagine file (either in Erdas or with 
gdal_translate) everything works fine.  What is it about tiffs that 
could possibly hang up Chameleon?  Why would Chameleon even be aware of 
input file format?  Don't MapServer and GDAL handle that?  I know 
they're fine because a non-Chameleon phpMapScript app renders the map 
fine, as does the CGI.



Paul Spencer wrote:

> Ken,
> to debug drawmap.php, you need to grab the URL from the image in the 
> chameleon app and load it directly in your browser.  You should then 
> see any error messages or debug output directly.  Often, problems with 
> a broken map image are related to error messages (or notices) being 
> output before the image contents, thus creating a corrupt image.
> If nothing shows up immediately on viewing the drawmap.php url, you 
> can then start to add some debugging code (echo) to drawmap.php to try 
> to discover what is going on.
> Cheers,
> Paul
> Ken-ichi wrote:
>> Hi list.  A while ago I posted an issue I'd been having with 
>> rendering TIFFs in Chameleon 
>> (http://lists.maptools.org/pipermail/chameleon/2004-August/thread.html#1245), 
>> but I never really resolved it.  Essentially, whenever I zoom in on a 
>> GeoTIFF so that the TIFF fills the whole map, Chameleon hangs and 
>> never displays the map image (I just get the spinner icon 
>> indefinitely and then a broken image icon behind it.  Try zooming in 
>> on the DRG (Test Raster) at
>> http://fisher.cnr.berkeley.edu/vtm/data/mapbrowse/
>> to see what I'm talking about.  I'm fairly sure this is a Chameleon 
>> issue, most likely with drawmap.php, because this mapfile renders 
>> just fine via the CGI, and with a rudimentary phpMapScript app like 
>> this one:
>> http://fisher.cnr.berkeley.edu/~kueda/mapscript_browse.phtml
>> The DRG is a 16M GeoTIFF from the California Spatial Information 
>> Library, so I don't think it's to blame.  You can check out my php 
>> and MapScript config at
>> http://fisher.cnr.berkeley.edu/~kueda/phpinfo_mapscript.phtml
>> I'm running MapServer 4.4.0, GDAL 1.2.5, and PHP 4.3.9.  Can anyone 
>> think of a reason this could be happening, or recommend a way to 
>> troubleshoot drawmap.php?
>> -Ken-ichi
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