In the end, this is the illum modifier... *I wonder about the src_theta *parameter
void brightdata noGeo_illum_dist
4 boxcorr noGeo_illum.dat source.cal src_theta
0
4 1 0.1 0.1 0.1 # 1, dimx, dimy, dimz
2015-11-11 17:56 GMT-03:00 Germ�n Molina Larrain <[email protected] <mailto:[email protected]>>:
    Hi Greg,
    Thanks very much for the information. I tried what you said, and I
    think that you might be slightly wrong.
    - At First I did what you said... multiplied the original A1 value
    in brightdata (127.324) by Pi and by R2 (0.05*0.05) and the
    returned number was ridiculously close to 1, which is the -m
    option I input.
    - I checked the surce.cal file, and the boxcorr requires A1, A2,
    A3 and A4... the first one being a multiplier and the others being
    the length, width and depth of the box. Using A1...A4 = 1 0.1 0.1
    0.1, I got the following results
    TOP VIEW
    <https://drive.google.com/file/d/0B2NfkTSl19hQVkdzN1JlWFllcE0/view>
    BOTTOM VIEW
    <https://drive.google.com/file/d/0B2NfkTSl19hQVXRvTXRWYV9hR2s/view?usp=sharing>
    One of them is using just ies2rad , the second is using ies2rad -i
    0.05 and the third one is transforming this to a box as explained
    before.... *THEY LOOK GOOD TO ME...?*
    I think the area and that kind of things has to be used for planar
    surfaces. right? I mean, for when we do crazier boxes...?
    Regards,
    Germ�n
    2015-11-11 16:40 GMT-03:00 Greg Ward <[email protected]
    <mailto:[email protected]>>:
        Hi Germ�n,
        Yes, it is a little more complicated, and you are right to
        worry about normals! Actually, it is the projected area that
        matters, which for the sphere is (mostly) constant. The main
        thing you need to do is to compute a first real brightdata
        argument (A1) equal to the existing one produced by ies2rad,
        multiplied by PI*R*R, where R is the radius of the original
        sphere. Multiplying the value thus by the projected area of
        the emitter gets you back to radiant intensity. Then, use the
        "boxcorr" function as the first string argument to the
        brightdata primitive in order that this radiant intensity is
        divided by the projected area in the appropriate direction
        during rendering.
        It would be prudent to verify the results by rendering
        illuminance in a large sphere around the light source before
        and after, just to make sure neither of us messed up!
        Cheers,
        -Greg
        *From: *Germ�n Molina Larrain <[email protected]
        <mailto:[email protected]>>
        *Subject: *Re: [Radiance-general] Luminaire modelling using
        Radiance
        *Date: *November 11, 2015 9:29:48 AM HST
        *
        Hello again guys,
        I have a question now.... I have been reading about all this,
        and I would like to input geometry surrounded by illum.
        However, ies2rad seem to only be able to generate a Sphere.
        How do I try this with different shapes? (i.e. a box) is it
        just a matter of deleting the Sphere and put a lot of
        Polygons with the same modifier? I am worried about normals
        and stuff like that.
        I hope I made myself clear, haha
        Regards,
        Germ�n
        2015-08-10 10:24 GMT-03:00 Germ�n Molina Larrain
        <[email protected] <mailto:[email protected]>>:
            well, thanks a lot guys! I have a lot to read, write, try
            and see now.... I will let you guys know how this goes
            and come back with a lot of new questions, haha.
            Best,
            Germ�n
            2015-08-08 19:52 GMT-03:00 Randolph M. Fritz
            <[email protected] <mailto:[email protected]>>:
                "Further to Randolph�s post, the idea is to wrap the
                luminaire
                geometry as tightly as possible using the shapes
                Randolph mentioned,
                but this enveloping geometry will have *illum*
                applied to it, not
                glow"
                Duh. Rob is, of course, quite correct.
                --
                Randolph M. Fritz, Lighting Design and Simulation
                +1 206 390 4477 <tel:%2B1%20206%20390%204477> ||
                [email protected] <mailto:[email protected]>
                On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >> <[email protected] >> <mailto:[email protected]>> wrote:
                > Thomas has great info on lamp color and using
                replmarks. Further to
                > Randolph�s post, the idea is to wrap the luminaire
                geometry as tightly as
                > possible using the shapes Randolph mentioned, but
                this enveloping geometry
                > will have *illum* applied to it, not glow. The glow
                is used to illuminate
                > the luminaire geometry itself so that it appears
                realistic in a rendering.
                > You apply glows to the lamp objects in the
                luminaire generally, or you could
                > apply them to any shades or lenses in the luminaire.
                >
                > The luminous intensity of the illum is derived from
                the input lumens in the
                > IES file and is modulated by a few cal files, which
                use the candela values
                > from the IES file. The lamp color utility can give
                you reasonable values to
                > use for the glows, based on lamp input lumens.
                Again, the glows illuminate
                > the local luminaire geometry, and the illums
                actually illuminate the space.
                > The ileum material is invisible when viewed
                directly, which is why you need
                > the glows to make the luminaries appear correct in
                a rendering. The flux
                > from the glow also does not make it past the illum
                geometry and so it does
                > not contribute to the scene illumination or any
                calculations.
                >
                > There is some info on using illums and glows here:
                >
                http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
                >
                > I did a bunch of crap with different illum geometry
                and cal files
                > (lboxcorr.cal et al.) and got pretty good at
                picking the best ones for the
                > jobs at hand (wall mounted sconces and stuff like
                that can be tricky to get
                > looking �right�), but never got around to posting a
                summary on that stuff. A
                > good place to start is just running a few different
                luminaire types though
                > ies2rad and see what you get, and then play with
                the output files from
                > there.
                >
                > Are we having fun yet?
                >
                > -Rob
                >
                > From: Randolph M. Fritz <[email protected]
                <mailto:[email protected]>>
                > Reply: Radiance general discussion
                <[email protected]
                <mailto:[email protected]>>>
                > Date: August 8, 2015 at 2:32:01 PM
                > To: Radiance general discussion
                <[email protected]
                <mailto:[email protected]>>>
                > Subject: Re: [Radiance-general] Luminaire
                modelling using Radiance
                >
                > The basic technique is to wrap the visible geometry
                of the luminaire, if
                > any, with a glow in a simple shape that actually
                radiates the light. The
                > glow is transparent, so that the geometry can be
                seen, and direct
                > illumination does not pass through the glow, so
                light can be used internal
                > to the glow to give the luminaire a realistic look.
                >
                > The glow geometry and description may be generated
                by ies2rad. IIRC only
                > four shapes are supported: sphere, rectangular,
                cuboid (box), and thin disc.
                >
                > Ies2rad does not support eulumdat and again, IIRC,
                has not been updated to
                > support the latest IES photometry standard, LM-63-02.
                >
                > --
                > Randolph M. Fritz, Lighting Design and Simulation
                > +1 206 390 4477 <tel:%2B1%20206%20390%204477> ||
                [email protected] <mailto:[email protected]>
                >
                > On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher >> <[email protected] <mailto:[email protected]>> wrote:
                >> Hi German.
                >>
                >> The most important information you need you will
                find in the ies2rad man
                >> page. In general you use it to create a library of
                luminaire *.rad and
                >> *.dat
                >> files which you can later reference into your
                scenes via xform. I found it
                >> more convenient and flexible for my exporters to
                create files with
                >> triangular markers and use "!replmarks ..." to
                place multiple luminaire
                >> files. That way you can later replace all
                luminaires in an array with a
                >> single change in the scene file.
                >>
                >> When you write a plugin you have to pay attention
                to the units of the ies
                >> file and adjust the -d parameter accordingly.
                Unfortunately ies2rad
                >> doesn't
                >> read that information from the file.
                >>
                >> The geometry in IES files is limited to discs,
                ovals, rectangles and
                >> extrusions of these shapes. Mostly you will find
                the 2 dimensional shapes
                >> for recessed and spot lights while the 3
                dimensional shapes are used for
                >> pendants (boxes and cylinders). If you want to
                avoid these crude things in
                >> your model and use detailed geometry instead (from
                a dxf file, for
                >> example)
                >> then you use the -i option to create an illum
                sphere. The sphere will be
                >> used with the luminance data generated from the
                ies file. You have to
                >> place
                >> the detailed geometry of fixture into the sphere
                yourself. ies2rad doesn't
                >> do that for you.
                >>
                >> I found that geometry provided by manufacturers is
                very detailed and can
                >> lead to problems in large models. MGF geometry
                information is extremely
                >> rare.
                >>
                >> You can use the -t option to set the lamp type.
                This defines the color
                >> temperature. The -m option allows you to set a
                maintenance factor that all
                >> artificial lighting calculations require. Not that
                some lamp type entries
                >> in
                >> the lamp.tab file already include a correction
                factor for the lamp so you
                >> have to take this into account when calculating
                the final value of -m. I
                >> found it safest to use "-t WHITE" (which does not
                have a correction) and
                >> lump all the efficiency reductions and maintenance
                factors together into a
                >> single -m value.
                >>
                >> European manufacturers provide are more likely to
                provide Eulumdat file
                >> specs for their luminairs. Sometimes they convert
                these for you into IES
                >> files. If you can only get LDT files you can use
                DIALUX or something
                >> similar
                >> to convert the LDT to IES files. It used to offer
                this option a few year
                >> ago, at least. There may be other converters out
                there, but I don't
                >> remember
                >> the names.
                >>
                >> Hth, Thomas
                >>
                >> On Fri, Aug 7, 2015 at 2:09 PM, Germ�n Molina Larrain >> >> <[email protected] <mailto:[email protected]>> >> >> wrote:
                >>>
                >>> Hello everyone,
                >>>
                >>> I think this might be a silly question, but I
                actually have not found too
                >>> much information on how to model luminaires using
                Radiance... I am asking
                >>> this because I want to add this feature to the
                plugin I am developing.
                >>>
                >>> What is the recommended method for modelling
                luminaires in Radiance? I
                >>> intend to use IES files as input. Hopefully I
                would also have the
                >>> geometry,
                >>> but I have to consider cases when this is not
                available.
                >>>
                >>> I know there is an IES2RAD program, but I am not
                quite sure how general
                >>> it
                >>> is. Also, I have heard about the use of illums (a
                sphere, for example)
                >>> that
                >>> covers the entire luminaire....?
                >>>
                >>> I am kind of lost, so if someone could give me a
                hint, I would really
                >>> appreciate it.
                >>>
                >>> Also, if someone know where to find information
                about IES files and their
                >>> format, that would also be really helpful.
                >>>
                >>> THANKS
                >>>
                >>> Germ�n
                >>>
                >>> _______________________________________________
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