[Chameleon] tiff hang

Yewondwossen Assefa assefa at dmsolutions.ca
Wed Dec 8 16:28:47 EST 2004

In your case, the selectOutputFormat done in drawmap.php would not pick 
up the OUTPUTFORMAT defined in your map file but the default output 
format created by mapserver for png24 (note that mapserver creates a 
default output formats for all formats that are supported and  not 
defined in the mapfile. The default png24 is created like this (code 
from mapoutput.c in mapserver):

         msAllocOutputFormat( map, "png24", "GD/PNG" );
         format->mimetype = strdup("image/png");
         format->imagemode = MS_IMAGEMODE_RGB;
         format->extension = strdup("png");
         format->renderer = MS_RENDER_WITH_GD;

  So in your case, I guess you could  change the name of the 
OUTPUTFORMAT defined in your map file to png24 :

      NAME png24

  Not sure to understand the pnghacks so I can not really comment on this.


Bart van den Eijnden wrote:

> Hi Assefa,
> my Chameleon app MAP file has the following:
>     NAME png
>     MIMETYPE image/png
>     EXTENSION png
>   END
> my Chameleon config has the following:
>     <context-param>
>         <param-name>image_type</param-name>
>         <param-value>PNG24</param-value>
>         <description>....</description>
>     </context-param>
> So I don't see how this could explain the difference ... okay, maybe 
> the  file goes through my png alpha hack now, since it is a static image 
> now  with extension png. That must be the cause for this.
> So using this approach you can use pnghacks to display the image 
> properly.  I could not get the png hack to work using the drawmap approach.
> Thanks.
> Best regards,
> Bart
> On Wed, 08 Dec 2004 16:03:05 -0500, Yewondwossen Assefa  
> <assefa at dmsolutions.ca> wrote:
>> Bart,
>>   Here is what could be happening : drawmap.php used the image_type  
>> parameter set in chamleon.xml to select the output format that will 
>> be  used (just before the rendering). Maybe there is a diffrence 
>> between  what you setup in the map file outputformat and the one which 
>> is  selected by drawmap.php. Could this explain your problem ? (Note 
>> that  $oMapSession->oMap->selectOutputFormat($szImgType) done in 
>> drawmap.php  compares first for the mimetype and then the name for all 
>> the  outputformat defined to do it's selection).
>>   The approch of writing the map to a temporary file does not use the  
>> selectOutputFormat.
>>   Both approchs use the same php mapscript draw function so the 
>> output  selection seems to be the only diffrence from what I can tell.
>> Later,
>> Bart van den Eijnden wrote:
>>> Assefa and list,
>>>  if I use this approach the 24 bit transparency problems in 
>>> Internet   Explorer (grey background) are also gone.
>>>  I reported those problems in the Mapserver bugzilla:
>>> http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1089
>>>  Is this explainable for you guys?
>>>  Best regards,
>>> Bart
>>>  On Wed, 08 Dec 2004 15:06:59 -0500, Yewondwossen Assefa   
>>> <assefa at dmsolutions.ca> wrote:
>>>> Ken,
>>>> Thanks for testing.
>>>> AFAIK, the changes would only affect the Query widget if it is used  
>>>> with  the parameters  HIGHLIGHTRESULTS and PERSISTENTRESULTS.  
>>>> Maybe  Paul can  comment on other widgets that I may have overlooked.
>>>>   As for the drawmap.php, It does several functionnalities (every  
>>>> thing  drawn in chamelon like map, scalebar, keymap) pass trough 
>>>> that  function.  The idea behind it is that if you assigning a URL 
>>>> to the  image source  (http::../drawmap.php?...), the main 
>>>> application page  does not need to  wait for the map to be drawn to 
>>>> load completly and  thus It is supposed  to give a better "smooth" 
>>>> looking apps.
>>>>   Your are the 2nd person who tried this solution and reported that  
>>>> the  application was faster considerably. When using the 
>>>> drawmap.php  method,  there is a time cost associated with calling 
>>>> the server,  loading the  session and then drawing the map. I would 
>>>> have imagined  that this  solution would improve the rendering time 
>>>> slightly (since  session  loading and call to the server are cut) 
>>>> but I am surprised a  bit to know  that It has considerable effect 
>>>> since I always thought  that the main  bulk of the time is taken by 
>>>> the map drawing.  I guess  a good profiling  might give us a better 
>>>> understanding.
>>>>   Anyhow I entered a bug 893 on this :
>>>>     http://www.maptools.org/bugzilla/show_bug.cgi?id=893
>>>> Later,
>>>> Ken-ichi wrote:
>>>>> Wow, not only did that solve my problem, but it increased map  
>>>>> rendering  speed considerably, even with no TIFFs!  Thanks, Assefa  
>>>>> and Paul.   Adding a flag in the widget tag to do this would be  
>>>>> really helpful.   Are there any widgets that don't work with this  
>>>>> adjustment, i.e. can I  alter our "production" copy of Chameleon 
>>>>> and  expect other Chameleon  projects on the server to work ok?  
>>>>> What  exactly is the purpose of  drawmap.php anyway?
>>>>> Thanks again.
>>>>>  -Ken-ichi
>>>>>  Yewondwossen Assefa wrote:
>>>>>> The changes are minmal : here is what I did :
>>>>>>   1) MapDHTML.widget.php : in function GetJavascriptVariables  
>>>>>> (around  line 468) :
>>>>>>    comment the 3 lines and add the 3 additional lines :
>>>>>>      //$url =   
>>>>>> WEBCOMMON."/wrapper/drawmap.php?map_session_mode=$nMapSessionMode&run_query=0&".SID.$szFatalImage;   
>>>>>>         //if (!$bCWCJSAPI)
>>>>>>         //$url .= "&dummy=".urlencode(microtime());
>>>>>>         $oMap = $this->moMapObject->oMap;
>>>>>>         $img = $oMap->draw();
>>>>>>         $url = $img->saveWebImage();
>>>>>>   2) in MapDHTML.js : function MapLayerDivImgOnLoad
>>>>>>     comment the line : //url = url + "&UniqId="+unique;
>>>>>> Please give it a try and let me know.
>>>>>> Paul, I think we can easily make this a configurable thing as far  
>>>>>> as  mapdhtml is concerned. I think there might be a problem 
>>>>>> though  with  the new query widget that diplays the selected 
>>>>>> element (and  keep the  selection persitently) but It can also be 
>>>>>> solved with few  changes.
>>>>>> What I propose is that Ken do the tests and if it solves his  
>>>>>> problem,  I will enter an enhancement bug on this with the 
>>>>>> changes  required and  we can implement it after that.
>>>>>> Later,
>>>>>> Paul Spencer wrote:
>>>>>>> Ken,
>>>>>>> this is very strange.  Chameleon is not aware of the image 
>>>>>>> formats  of  the underlying data, it just uses mapscript to do 
>>>>>>> the drawing.
>>>>>>> Another solution to this problem may be to have the MapDHTML  
>>>>>>> widget  render the map to a file and then load the image source 
>>>>>>> in  the page  rather than use drawmap.php.
>>>>>>> We did this for another client who was having a strange problem  
>>>>>>> with  images half loading due to some sort of firewall problem  
>>>>>>> (only in IE  strangely).
>>>>>>> I've cc'd Assefa since he was the one who sorted that out.   
>>>>>>> Assefa,  can you post the solution to getting MapDHTML to render 
>>>>>>> to  a file?   Do you think we could make this a configurable 
>>>>>>> parameter  in the  MapDHTML widget (like DELAYDRAW="[true|false]" 
>>>>>>> or  something)?
>>>>>>> Cheers,
>>>>>>> Paul
>>>>>>> Ken-ichi wrote:
>>>>>>>> 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.
>>>>>>>> Argh.
>>>>>>>> -Ken-ichi
>>>>>>>> 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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Assefa Yewondwossen
Software Analyst

Email: assefa at dmsolutions.ca

Phone: (613) 565-5056 (ext 14)
Fax:   (613) 565-0925

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