In article <3dd38dbe$1@news.povray.org> , "Tom Melly" <tom### [at] tomandlucouk>
wrote:

> Huh? I think you're missing the point.

No:

> 34, 43,11, 76, 32, 2, 23, 73, 83, 23, 76, 63, 31,63,68,65
>
> Numbers 1 to 8 add to 294, 8 to 16 add to 472. Without knowing the render time
> of each frame prior to rendering, the only way I can ensure that both renders
> finish at the same time is to start one render at one end of the sequence, and
> the other render at the other end of the sequence.

You may have noticed that I gave _two_ ways to do it.  Either even and odd
frames or splitting in the middle.

BTW, your method will not make sure both renders end at the same time.  To
the contrary, starting from both ends has exactly the same properties as
starting anywhere else because you can never know that the last frame
rendered in one instance of POV-Ray will not take longer than the last frame
of the other instance's "last" frame being rendered.

In essence, if you seek perfect (or close to that) distribution of load on
two systems with different speed, you would have to use really long
sequences which have no "exotic" frames that take much longer or much less
time than the average.  Otherwise such a simple attempt of load distribution
will simply not give you any advantage at all.

However, a simple way to achieve some distribution is to use POV-Ray's
"continue" feature.  While probably (I would have to try) rendering the
animation directly won't work, creating a simple batch file that sets the
external "clock" directly will perform exactly as it should as long as the
result images are kept in the same directory on one system and that systems
prevents files to be opened by multiple processes for writing simultaneously
(which should be the default behavior, so there should be no problem).  If
you now start POV-Ray with the continue option on both systems and share the
result image directory, POV-Ray will skip rendered images and fail on
partially rendered images (the other instance is rendering it already).
While not optimal, this scales much better than just starting a render from
the end and one from the beginning -- you can use more than just two
systems.  In fact this is so trivial, it should be possible to do it
comfortably with a DOS-style shell scripting - you would not even have to
calculate the clock values yourself but could leave it to the shell script.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message