[Radiance-general] 2.5-phase method and gendaymtx

[Andrew McNeil]

Axel,

This line of your script may be the cause of your problem:

> gendaymtx -5 -d -m $REINHART -c 1 1 1 -O1 $WEA > $dsmx


-d works by changing the sky color to 0 0 0. Then the -c option later in
your command negates the -d option by changing the sky color to 1 1 1.

I only know this because I made this mistake in a script I sent to Rick.
Rick discovered that it wasn't working and Greg told us how gendaymtx
actually works.

Andy




On Thu, Feb 6, 2014 at 3:08 PM, Greg Ward <gregoryjward at gmail.com> wrote:

> I can't pretend to understand the inner workings of DaySim, either, but I
> know there are some differences with rcontrib.  These differences will lead
> one to prefer one or the other depending on simulation needs:
>
> o rcontrib uses a form of pure Monte Carlo to break illumination
> contributions into any desired number of components.  This flexibility
> allows it to be applied in a wide variety of circumstances, such as the
> 3-phase and 5-phase method.
>
> o DaySim computes 145 components throughout a more standard application
> of the Radiance rendering & calculation tools, allowing it to take full
> advantage of irradiance caching at the expense of some generality.
>
> o rcontrib is a "dumb" but highly programmable tool, and by itself
> doesn't do anything useful.  It currently needs conjoined with a script,
> cal file or program to make it useful, and a number of these have been
> written such as genBSDF, genklemsamp, klems_int.cal, etc.
>
> o DaySim includes a complete simulation of daylight control in a single
> interior space and is much easier to apply in typical situations, but may
> be harder to adapt to unusual conditions.
>
> I hope this helps.  Maybe Christophe can chime in with his thoughts.
>
> -Greg
>
> *From: *Zack Rogers <zrogers at daylightinginnovations.com>
>
> *Date: *February 6, 2014 2:30:48 PM PST
>
>
>  Hi Axel,
>
> I can't say I fully understand the innerworkings of the DS algorithms but
> I believe they are really just an implementation of rcontrib probably
> similar to what you are working on.  There is a little diddy it uses called
> "gen_dc" that automatically generates the skypatch and solar array DC
> files.  This calls out to an "rtrace_dc" program which I think was the
> precursor to rcontrib.  It then has a couple programs that use those DC
> files to perform annual simulations.  One called "ds_illum" which uses the
> DC files and a weather file, creates perez sky models and assigns flux to
> patches and solardisc locations, and ultimately creates an annual
> illuminance file.  I would like to see this annual illuminance file format
> become a standard as well.  All the new dynamic daylight metrics we are
> developing can be calculated from this one annual illuminance file and SPOT
> creates an identically formatted annual illuminance file.
>
> Regards,
> Zack
>
>
> On Thu, Feb 6, 2014 at 2:11 PM, Axel Jacobs <jacobs.axel at gmail.com> wrote:
>
>> Hi Zack,
>>
>> I have to admit that calling it 2.5-phase was a bit tounge-in-cheek of
>> me.  All those different phases keep confusing the living daylight out of
>> me, and by reading the posts on this list, others see to share similar
>> sentiment.
>>
>> Anyhow, and I'm glad you pointed this out. My intention with the little
>> 2.5p exercise was exactly this--to compare Radiance to DaySim.  I have to
>> admit that to me, DS is a bit of a black box, but this is probably only
>> because I don't use it much.
>>
>> Also, nailing down a nomenclature of dds terminology is a great idea.  I
>> think there is much confusion as to what the different methods and software
>> packages can and cannot do, so having some overview of capabilities, fields
>> of application, accuracy, limitations etc would be great.
>>
>> And:  How about test cases?  Has anybody ever compared, say, DaySim
>> against Radiance for DDS.  There are quite a few clever algorithms that
>> only seems to exist in DS, not anywhere else, making a verification of DS
>> results against Rad rather challenging.  What can DS do that Radiance
>> can't, and vice versa?
>>
>> Best
>>
>> Axel
>
>
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>
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