[mapserver-users] Corrupt image output

[Tamas Szekeres]

Mike,

Did you experience the same problem when calling tile.php directly
when rendering an individual tile?

Best regards,

Tamas


2008/8/19 Mike Leahy <mgleahy at alumni.uwaterloo.ca>:
> Hello list,
>
> I'm wondering if anyone can help me figure out a problem I'm having with
> corrupted output from from a tiled geotiff dataset I'm using in a ka-Map
> environment.  You can see what's happening to the imagery here:
> http://img527.imageshack.us/my.php?image=corrupthd1.png
>
> This generally happens when I'm zoomed in fairly close, and usually with
> this high-resolution image dataset.  However, I can get corrupted output for
> other raster datasets (all geotiff, but not always tiled).  It seems to
> happen when the machine is processing most intensively (i.e., usually when
> the imagery is being rendered by ka-Map).  It also seems to be limited to
> the laptop I am using, which is running F7-x86_64.  In contrast, I have an
> actual server (F8-x86_64), which has a virtually identical setup (with
> respect to MapServer and its various dependencies), but with lots more cpu
> cores and ram, and it's having no trouble at all (as far as I have noticed).
>
> The corruption in the output from the same application my laptop is not
> always the same - if I clear the cache for ka-Map and re-render the images,
> I'll get similar artifacts appearing in the output (red, green, blue and/or
> black rectangles), but they will vary in size and location.  It happens for
> both GD/AGG drivers, and JPEG/PNG output formats.
>
> Until now, I figured it was just a problem with limited memory on my laptop
> (it was always around 100% when rendering this imagery on the web service +
> viewing the application in a browser), but now I've upgraded the ram -
> there's plenty of spare room and I'm still getting the same problem.  I just
> finished upgrading Gdal from 1.5.0 to 1.5.2, and that didn't help any.
>
> Basically, the only real differences I can think of between my laptop and my
> server are the number of cpu cores (1 on my laptop vs. 8 on the server), and
> possibly the versions of some of the underlying libraries in the system.
>  Does anyone know where I should start looking to find the cause of this?
>  Or perhaps somebody recognizes this problem, and knows what I might be
> doing wrong...
>
> Thanks for any suggestions,
> Mike
>
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