[Radiance-general] rtcontrib

[Jia Hu]

Many thanks!!!

On Thu, Jul 14, 2011 at 12:52 PM, Greg Ward <gregoryjward at gmail.com> wrote:

> Hi Jia,
>
> I will answer your questions the best I can inline...
>
> > From: Jia Hu <hujia06 at gmail.com>
> > Date: July 14, 2011 9:12:12 AM PDT
> >
> > Thank you! I have other questions related to this program.
> >
> > (1) Question 1:
> >
> > In the case that both of "-f", "-b" and "-m" are used, the .cal algorithm
> and "-b" option are applied to objects with "-m" materials, for example,
> >
> > vwrays -ff $vw |rtcontrib @image.opt -ffc $(vwrays -d $vw) -f
> tregenza.cal -b tbin -o images/patches/p%03d%s.hdr \
> > -m sky_glow -m ground_glow -w testroom_whitesky.oct
> >
> > If I replace "ground_glow" with "ceiling_mat", the .cal will applied to
> "ceiling" geometry and divide ceiling into many patches according to the ray
> direction and intersection with ceiling?
>
> Yes, the bins will still be based on ray direction due to the "tbin"
> definition in "tregenza.cal", but will apply to rays striking surfaces using
> "ceiling_mat" instead of "ground_glow".  The intersection position on the
> ceiling will not affect "tbin" since it doesn't use this information, so the
> same direction at one corner of the ceiling will go to the same bin as a ray
> hitting the opposite corner in that direction.
>
> My understanding of rtcontrib is that it calls rtrace to trace ray as the
normal process but rtrace onlys reports the ray coefficient modifer in
modifer list specified by "-ti" in rtrace.

> >
> > (2) Question 2:
> >
> > Assume my model has two windows in the south wall and one sensor in the
> interior building, and I wish to calculate the daylighting coefficient of
> each patch of sky and each window to the illuminance at the sensor point.
> The result is like a matrix as follows:
> >
> >                     SkyPatch001,       SkyPatch001,
> > Window01     coefficient (RGB)   coefficient (RGB)
> > Window02     coefficient (RGB)   coefficient (RGB)
> >
> > Each coefficient shows the contribution of each sky patch and each window
> to the sensor illuminance. Can I achieve this in one rtcontrib command?
> > Is the following expression right?
> >
> > [input ray] | rtcontrib -f tregenza.cal -o window_%s.data -b tbin -m
> window01_mat -b -b tbin -m window02_mat  [other necessary options]
>
> You don't need to give the "-b tbin" option twice, and the "-b" option by
> itself will generate an error, but otherwise it is OK.  Note that this
> command neglects any exterior obstructions that might interfere with the
> travel of a sample ray from the exterior of the window to the sky.  If your
> building has external shades or obstructions outside, the above technique
> will not produce accurate results.
>
> The general ability to choose combined interactions in rtcontrib is
> lacking.  E.g., you can't ask for all rays that pass through "window1" then
> go on to intersect "building2" and reflect to "skypatch17".  It would be a
> useful feature to add, but such accounting is problematic.
>
> You are right!  it is problematic when external shades or obstructions
exist. Unfortunately my case has external shades. Hope you could add this
feature in the near future.

 Thanks,

Jia
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