[Radiance-general] Radiance 5.0 installation on ubuntu 14.04

[Greg Ward]

Oh, but I did neglect to mention a critical point, which is that rfluxmtx figures out the hemisphere orientation(s) from the surface or surfaces you specify in your source and receiver files.  So, it's very important that surface normals are directed in a certain way -- specifically, receiver normals point in the direction of the sampled hemisphere, and source normals point *away* from the hemisphere we want to sample.

Though this may seem counter-intuitive, it follows naturally from the typical orientation of windows in Radiance, whose normals face the interior.  When the windows are acting as the receivers in a matrix calculation, such as for a view or illuminance value matrix, their normal is looking towards the interior hemisphere being sampled.  When their role changes to make them the source surfaces, as when you calculate the exterior daylight matrix, they are still facing the correct direction to have their opposite-side hemisphere send out samples to the exterior.

In this way, rfluxmtx allows you to re-use your receiver description in one run as the source description in another run.

I'm hoping this makes sense, because I mention it in the man page, but it's not quite obvious and I did it the wrong way around the last time I used the tools, myself(!)

Best,
-Greg

rfluxmtx.pdf

> From: "Gregory J. Ward" <gregoryjward at gmail.com>
> Subject: Re: [Radiance-general] Radiance 5.0 installation on ubuntu 14.04
> Date: March 18, 2016 4:40:09 PM PDT
> 
> Hi Humberto,
> 
> The rfluxmtx command takes over for genklemsamp and calls rcontrib with the options needed for correct operation.  You don't need to specify the bin or the .cal file(s), as rfluxmtx takes care of that part.  You do need to set both the "u=Z" (or whatever) up-direction and the desired hemispherical sampling type (e.g., "h=r4") in your Radiance scene description handed to rfluxmtx as the source or receiver(s).
> 
> The reinhartb.cal file is more general than the original reinhart.cal file, and uses slightly different mechanisms (hence the need for a new name).
> 
> I hope this helps, and thanks to everyone for pitching in.  I realize that the changes made post-tutorial have caused a good deal of confusion, but we hope to get it all sorted out in the end.
> 
> Cheers,
> -Greg
> 
>> From: Humberto Antunes <hs.antunes at campus.fct.unl.pt>
>> Subject: Re: [Radiance-general] Radiance 5.0 installation on ubuntu 14.04
>> Date: March 18, 2016 2:49:55 PM PDT
>> 
>> Hello again everybody,
>> 
>> I have a question related to the command rfluxmtx.
>> While using rcontrib to generate the view matrix we had to set the window orientation with the command -b kbinS or (N,E or W), how do we do that in the rfluxmtx? Is it set by the "u" variable or it is not needed to do this with the rfluxmtx command?
>> 
>> Also, as reinhart.cal file been replaced for the reinhartb.cal?
>> 
>> Best regards
>> Humberto A.
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