[Radiance-general] IES files and MGF geometry

[Axel Jacobs]

Thanks, Greg.  Will give this a try.

Best
Axel


On 5 November 2014 17:04, Greg Ward <gregoryjward at gmail.com> wrote:
> Hi Axel,
>
> Yes, as Randolph reminds me, LM-63 did have the geometry spec in there.  All I remember is that it was never supported by anyone.  At least we are using MGF in our XML specification for complex fenestration system BSDFs, so it's not a complete waste.
>
> Regarding the local box correction, you could take out the third term "noneg(abs(Pz-Dz*Ts)-A4/2)*A2*A3" from the formula:
>
> lboxprojection = (      noneg(abs(Px-Dx*Ts)-A2/2)*A3*A4 +
>                         noneg(abs(Py-Dy*Ts)-A3/2)*A2*A4 +
>                         noneg(abs(Pz-Dz*Ts)-A4/2)*A2*A3 ) / Ts;
>
> I think that should work.
>
> Cheers,
> -Greg
>
>> From: Axel Jacobs <jacobs.axel at gmail.com>
>> Subject: Re: [Radiance-general] IES files and MGF geometry
>> Date: November 5, 2014 8:57:01 AM PST
>>
>> Hi Greg,
>>
>> I only know about this MGF embedding from the ies2rad man page, and
>> thought it might solve my problem:
>>
>> " -i rad    Ignore the crude geometry given by the IES input file and
>> use  instead  an  illum
>>                 sphere  with radius rad.  This option may be useful
>> when the user wishes to add a
>>                 more accurate geometric description to the light
>> source model, though  this  need
>>                 is  obviated by the recent LM-63-1995 specification,
>> which uses MGF detail geome-
>>                 try.  (See -g option below.)"
>>
>> This sounds rather more positive than the situation appears to be now.  Oh well.
>>
>> As you say--I would need near-field for my bollard.  Thank for sending
>> the projection formula.  With the NF-correction for boxes already in
>> the code, would a square bollard (again w/o bottom and top) be any
>> easier to describe?  A square imposter is still a lot better than a
>> hovering crystal ball.
>>
>> Many thanks
>>
>> Best
>> Axel
>
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