[Radiance-general] incident ray angles

[Jia Hu]

Hi Greg and David,

That is great.  I looked at the man page of rsensor program, that is what I
need.  I have a few questions for which I am struggling.

   1.  you mentioned I still have to use a cone to cutoff light even if I
   define the sensitivity data files?  should I list all from 0-90 (row
   degree) in the row or just view angle range (e.g., from 0 - 54 deg in row)?
     does the program do some interpolation for angles are not defined in the
   sensor files?
   2. Our program was built based on Daysim, and use gen_dc to generate
   daylight coefficient and us ds_illum to calculate the sensor readings. The
   readings are cosine weighted, but it seems no way to integrate rsensor with
   ds_ill or .dc files. I understand the 3 or 5 phase DC methods is good to
   handle this. Since we already have the code from Daysim, it may be easy to
   directly integrate resensor with current Daysim generated .dc files? Do you
   have some suggestion?
   3. If we use three phase DC method, we have to generate the BSDF files,
    genBSDF +f +b will double the time, so for blinds in the south wall
   settings, I only need use deault (+b only, not +f), is tha right?  +b will
   generate Transmission From (Window 6 convention), is that right?

  Thank you very much,

Jia


On Thu, Feb 20, 2014 at 4:29 AM, Greg Ward <gregoryjward at gmail.com> wrote:

> Have you investigated the program "rsensor"?  It should be able to handle
> any distribution you like.
>
> By default, the -I option of rtrace gives you a cosine-weighted irradiance
> value.  If you need to add a cut-off, you can compute -I in the apex of a
> black cone of the appropriate size.
>
> -Greg
>
> *From: *Jia Hu <hujia06 at gmail.com>
>
> *Date: *February 20, 2014 8:45:33 AM GMT+01:00
>
>
>  Hello,
>
> I have a sensor and the sensor has different readings according to angle
> between incident ray and normal. Theoretically, this readings should be
> [cos(theta)*value of incident rays] hitting the sensor point (theta = angle
> between ray hitting the surface and sensor normal).  However,t our sensor
> is not this  relationship and I have to adjust the simualtion results to
> fit the actual sensor readings.
>
>
>    - one of the methods I can think of is to get directions of all the
>    incident rays hitting the sensor point and then calculate all the angles
>    between incident rays and sensor normal, and adjust the radiance values
>    before using rtrac to calculate the actual illuminance values.  Is that
>    feasible?   I notice there is a "t" option in rtrace, but it will return
>    all the rays, not just rays hitting the sensor points.
>    - Radiance traces only 1 ray from the sensor points or sample a number
>    of rays from sensor point? (my understaning was that rtrace first traces a
>    number of rays to check DIRECT light source and get the results, and then
>    traces a SINGLE ray following the sensor normal and then sampling more when
>    hitting a surface? if in this case, how can I determine the anges of direct
>    and indirect rays?)
>
>
> Thanks,
>
> jia
>
>
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