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Raster rendering bug and 'Segmentation fault' error #799

artemp opened this Issue October 11, 2011 · 8 comments

2 participants

Artem Pavlenko Dane Springmeyer
Artem Pavlenko

Large semi-transparent paletted PNG images (hillshade layer for the whole world, see attached test data) rendering bug. PNG part of XML used (for example):

 <Style name="zl04">
     <RasterSymbolizer opacity="1.0" mode="multiply" scaling="bilinear8" filter-factor="-1" /></Rule>

 <Layer name="zl04">
     <Parameter name="type">gdal</Parameter>
     <Parameter name="file">/home/mapnik/raster/zl04.png</Parameter>

Using Mapnik2 r3009 and GDAL 1.8.0-1 under Debian.

Without additional vector data:

  1. At the 2nd zoom level get an error: 'Segmentation fault'.
  2. 1st zoom level - OK.

With additional vector data:

  1. At the 3rd zoom level get an error: 'Segmentation fault'.
  2. At 2nd zoom level get dark tiles without hillshade (not whole world, but 3/4 part of it).
  3. 1st zoom level - OK.
Artem Pavlenko

[Andrey VI] [ test data (3.5 MiB)]

Artem Pavlenko

[springmeyer] Andrey, can you try applying this patch:

Index: src/image_util.cpp
--- src/image_util.cpp  (revision 3040)
+++ src/image_util.cpp  (working copy)
@@ -363,7 +363,7 @@
         ys = (y*source_height+offs_y)/target_height;
         int ys1 = ys+1;
-        if (ys1>=source_height)
+        if (ys1>=source_height-1)
         if (ys<0)
@@ -381,7 +381,7 @@
                 xprt = tw2;
             xprt1 = target_width-xprt;
             int xs1 = xs+1;
-            if (xs1>=source_width)
+            if (xs1>=source_width-1)
             if (xs<0)
Artem Pavlenko

[springmeyer] are you sure? are you sure the patch was applied correctly and that you reinstalled fully? are you using bilinear8 and the latest mapnik svn HEAD?

Artem Pavlenko

[Andrey VI] Unfortunately, this patch doesn't resolve any problem.

Artem Pavlenko

[Andrey VI] Yes, I'm sure that the patch was applied correctly. Now I have Mapnik2 r3047 installed.
But now I'm not sure that using bilinear8 with paletted PNG was a good idea. And that's why...[[BR]]
Initially (one month ago) I tried to render my colour PNG hillshade layer with rule

 <Style name="zl04">
     <RasterSymbolizer opacity="1.0" mode="multiply" scaling="fast" filter-factor="-1" /></Rule>

but got a black and white image of the hillshade. Then I've changed scaling to "bilinear8". That solved the problem with colour, but led to other problems described above.[[BR]]
Today I've changed scaling settings back to "fast", and now it works properly - I get colour hillshade. But with bilinear8 it still doesn't work. And, probably, it should not work. Correct me if I'm wrong.[[BR]]

So, I don't know what has changed in code in the last month, but now I can use the "fast" option with my PNGs.

Artem Pavlenko

[springmeyer] pushing to 2.0.1

Dane Springmeyer

pushing to 2.1.x

Dane Springmeyer

closing in preference of #1529

Dane Springmeyer springmeyer closed this November 07, 2013
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