Hi,
   I am working on povray and the objective is to test if povray is build
correctly across compilers for different optimizations. I have choosen the CPU
benchmark provided at http://www.povray.org/download/benchmark.php for this
exercise. I have enabled "All_File=povray.log" in the benchmark.ini to capture
the povray log.
   But I see that the povray log file generated has different output for
different compiler but the image file size remains same. A sample of the
parameters that are differing are given below:
----------------------------------------------------------------------------
Ray->Shape Intersection          Tests       Succeeded  Percentage
----------------------------------------------------------------------------
Box                          different        different      different
Cone/Cylinder                different        different      different
CSG Intersection             different        different      different
CSG Merge                    different        different      different
Fractal                      different        different      different
Height Field                 different        different      different
Height Field Box             different        different      different
Height Field Triangle        different        different      different
----------------------------------------------------------------------------

where "different" implies the number of "Tests" "Succeeded" and "Percentage" is
different for different compilers.

Can anyone please help me to understand how to verify if the rendering is done
correctly using the log file? Or any other method.

Thanks in advance,
Anupama

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On 01/20/2011 05:20 AM, anupama wrote:
> Hi,
>    I am working on povray and the objective is to test if povray is build
> correctly across compilers for different optimizations. I have choosen the CPU
> benchmark provided at http://www.povray.org/download/benchmark.php for this
> exercise. I have enabled "All_File=povray.log" in the benchmark.ini to capture
> the povray log.
>    But I see that the povray log file generated has different output for
> different compiler but the image file size remains same. A sample of the
> parameters that are differing are given below:

Well you didn't say, but is the assumption that you're doing this using
one of the latest versions of povray a safe one? If so there is a
build-in and scene file version that's been updated for the those
releases. They are identical ... the built-in version is meant to run a
certain way (a particular image size, and it writes no output file) but
does write an output log in the current directory when it completes. The
scene file version located at ~scenes/advanced/benchmark.pov is
identical in the respect that is produces the same image, however you
are able to change the parameters with which it runs ... image size,
tracing options, write an output file etc. I would be a little surprised
that you would see any significant difference in the output stats across
different platforms ... perhaps I've misunderstood what is it exactly
you're trying to accomplish.

Jim

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Am 20.01.2011 10:20, schrieb anupama:
> Hi,
>     I am working on povray and the objective is to test if povray is build
> correctly across compilers for different optimizations. I have choosen the CPU
> benchmark provided at http://www.povray.org/download/benchmark.php for this
> exercise. I have enabled "All_File=povray.log" in the benchmark.ini to capture
> the povray log.
>     But I see that the povray log file generated has different output for
> different compiler but the image file size remains same. A sample of the
> parameters that are differing are given below:
> ----------------------------------------------------------------------------
> Ray->Shape Intersection          Tests       Succeeded  Percentage
> ----------------------------------------------------------------------------
> Box                          different        different      different
> Cone/Cylinder                different        different      different
> CSG Intersection             different        different      different
> CSG Merge                    different        different      different
> Fractal                      different        different      different
> Height Field                 different        different      different
> Height Field Box             different        different      different
> Height Field Triangle        different        different      different
> ----------------------------------------------------------------------------
>
> where "different" implies the number of "Tests" "Succeeded" and "Percentage" is
> different for different compilers.
>
> Can anyone please help me to understand how to verify if the rendering is done
> correctly using the log file? Or any other method.

Try using "+WT1" to use just a single render thread. With multiple 
threads, OS scheduling adds a random element to the render, leading to 
some differences.

You may also try "+HR" which should increase reproducability, but 
currently it's not a cure-all.

Also note that different platforms might be using different rounding 
modes for floating point arithmetic, which may affect the result as well.

The effects on rendered output should be very subtle, but render 
statistics will differ nonetheless, so I'd suggest comparing the output 
images instead.

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