[Radiance-general] Understanding rtcontrib

[Thomas Bleicher]

I was following Axel's tutorial myself yesterday and had the same
problem that Chris describes. At least I managed to change my
file limit ...

On Sat, Feb 6, 2010 at 9:38 PM, Greg Ward <gregoryjward at gmail.com> wrote:
> Ah.  Sounds like you're running up against a system limit on the number of
> open file descriptors, which is typically set to 256.  I don't know how to
> overcome this.  The ulimit command should provide help, but I can't get it
> to behave for me.

On Mac OS X the max number of open files is limited to 256 per
user process. That's pretty low and not sufficient for any subdivision
of the Tregenza sky pattern.

To change the open files limit (on OS X!) I created a file
"/etc/launchd.conf" with the line "limit maxfiles 1024 unlimited"
and I set the kernel limit with "sysctl -w kern.maxfiles=1024".

After a reboot I could set the shell's limit with "ulimit -n 1024".
This can go into your ".profile" if you're going to use it a lot.

I had a few odd observations regarding the missing or incomplete
patch files but that seems to be solved now  (just tried it with MF:2
and it worked fine). I am still puzzled by the fact that creating all
these image doesn't seem to take much time at all (a few minutes
at max). When I tried the "vwrays | rtrace" example yesterday it
took half an hour to produce the image ...

Further down the tutorial you will have to replace the "seq"
command in Axel's scripts (not available on OS X). A simple
loop with a counter will do.

> When I use reinhart.cal, I don't usually produce separate
> component files for this reason.

Before Axel's tutorial I didn't know about reinhart.cal and the
use of genskyvec. It feels very elegant this way; better than
doing a separate calculation for defined sun positions like
daysim.

At the moment I just have a major problem with the quantities
in my simulation. At the end I achieve roughly 10% of Axel's
example values and the TFS values look just wrong ...

Anyway, a big thanks to Axel for this introduction.

Regards,
Thomas