[Radiance-general] RE: Prismatic glazing simulation in PMAP usingSiteco data

Mon Jun 14 20:04:10 CEST 2004

Anthony,

Raphael Compagnon is the author of prism2. His code has been validated and I am very happy with it. 

There are 7 different prismatic panels from Siteco/Bartenbach - there is no standard prismatic panel. Which one do you mean? For redirecting light from a vertical light pipe onto the horizontal workplane at an incidence angle of 45 degrees, the easiest device seems to be a mirror/two mirrors mounted at the bottom of the pipe. 

You need a good setup for testing to get meaningful results. This is expensive. Meters are the other problem. I am building a setup right now and my students have been working on it for 3 months (on and off). I am using a 1000W metal halide floodlight with a near parallel beam as a light source. Everything else makes weak signal-to-noise ratios with values below 5 Lux or so. 

Martin

	-----Original Message----- 
	From: Anthony J. Farrell [mailto:anthony.farrell at dit.ie] 
	Sent: Mon 6/14/2004 1:53 PM 
	To: radiance-general at radiance-online.org 
	Cc: 
	Subject: [Radiance-general] RE: Prismatic glazing simulation in PMAP usingSiteco data

	Thanks Roland, Martin for input,

	I meant to make to reference to the Prism1 and Prism2 commands in the 3.5
	release of Radiance. I am uncertain of the function file command line

	mod prism1 id
	5+ coef dx dy dz funcfile transform
	0
	n A1 A2...An where the new direction variables

	So if I wanted to redirect light from a vertical glazed window down at an
	angle of 45 degrees onto the working plane what values would I substitute in
	for A1 etc?

	* DxA DyA DzA and are the normalised direction to the target light source
	* dx, dy, dz are?

	I sketch of the dimensions would be very helpful, as I just can't picture
	the above scenario.

	Roland, Is it possible to use Prism1 or Prism2 commands in the PMAP version
	of Radiance to forward raytrace from the photon port (the target light
	(*luminance* source?)to the target illuminance source (the working plane)?

	Martin, could is it possible to model a standard prismatic panel that
	redirects vertical light from a light pipe for example, out at an angle of
	45degrees onto the working plane? I will be testing one of the siteco panels
	on my test rig so would be interesting to compare the results.

	Regards,

	Anthony.

	-----Original Message-----
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	[mailto:radiance-general-bounces at radiance-online.org]On Behalf Of
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	Sent: 11 June 2004 21:04
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	Subject: Radiance-general Digest, Vol 4, Issue 9

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	Today's Topics:

	   1. rholo & .hif files (O Graf)
	   2. Re: Fwd: errors from hdrgen (Martin Matusiak)
	   3. Fwd: Re: [Radiance-general] Fwd: errors from hdrgen
	      (Martin Matusiak)
	   4. Prismatic glazing in radiance PMAP (Anthony J. Farrell)
	   5. Re: Fwd: errors from hdrgen (Greg Ward)
	   6. Re: Fwd: errors from hdrgen (Greg Ward)
	   7. Re: Prismatic glazing in radiance PMAP (Roland Schregle)
	   8. RE: Prismatic glazing in radiance PMAP (Martin Moeck)

	----------------------------------------------------------------------

	Message: 1
	Date: Fri, 11 Jun 2004 12:21:53 +0100
	From: O Graf <s0343631 at sms.ed.ac.uk>
	Subject: [Radiance-general] rholo & .hif files
	To: radiance-general at radiance-online.org
	Message-ID: <1086952913.40c995d153a11 at sms.ed.ac.uk>
	Content-Type: text/plain; charset=ISO-8859-15

	Hi!

	What is actually the trick for setting the right values for the 'section'
	variable in a .hif file? The rad-file which I use contains a laser scan of a
	real room and I have no idea what are the right values for the 'section'
	variable. Every time I change the values the actual grid appears somewhere
	in
	the middle of the whole scenery and I get such warnings as

	          dev/ogl.hdi: no sections visible from this view

	if I try to turn around or to zoom. I understand why these warnings come,
	but I
	would like to know how I can estimate the values for the section to avoid
	the
	warnings and to be able to see the whole room and not only 2 walls.

	Another funny thing is that the whole room stands on its side, i.e. lines
	that
	are supposed to be vertical appear horizontal. First I thought the view
	direction might be wrong, but if I run the same .oct-file with rview using
	the
	same view-file everything is perfect. In addition to the right view
	direction
	the rview-command produces colored images and rholo gives only grey values
	from
	the same .oct-file. Is there a particular reason for such different results?

	regards,

	Olga

	------------------------------

	Message: 2
	Date: Fri, 11 Jun 2004 14:17:29 +0200
	From: Martin Matusiak <alex at juventuz.net>
	Subject: Re: [Radiance-general] Fwd: errors from hdrgen
	To: Radiance general discussion <radiance-general at radiance-online.org>
	Message-ID: <200406111417.29402.alex at juventuz.net>
	Content-Type: text/plain;  charset="iso-8859-1"

	> I hdr'ed all ouf the 13 images in one go, and apart for some 'poor
	> convergence' (orders 1, 3, 4 and 5) warnings, it worked fine. There is
	> no apparent distortion.

	I repeated the process using the manual mode of the camera rather than
	aperture priority. Again 13 images (same room, scene was a bit different as
	I
	eliminated the sky in the framing) and I was able to compute a hdr. But the
	alignment problem still persists, I use the -a switch to turn it off.

	Later I took a couple more images and used the calibration data to compute a
	hdr and read the luminance values off it. It turns out that those are
	somewhat accurate so that's a good sign!

	However, I'm still not quite satisfied. Obviously, the calibration procedure
	is meant to give a most accurate static description of the camera, but I
	used
	the camera's automatic whitebalance correction, so that's a variable. My
	question is a complete novice one: how does the whitebalance affect the
	luminance? What can I do to eliminate this variable (if it is significant).

	Martin

	------------------------------

	Message: 3
	Date: Fri, 11 Jun 2004 14:21:55 +0200
	From: Martin Matusiak <alex at juventuz.net>
	Subject: Fwd: Re: [Radiance-general] Fwd: errors from hdrgen
	To: radiance-general at radiance-online.org
	Message-ID: <200406111421.55929.alex at juventuz.net>
	Content-Type: text/plain;  charset="iso-8859-1"

	I forgot to mention that my "cvs build" of hdrgen is from last week, so
	there
	could have been changes from the version you have.

	Martin

	----------  Forwarded Message  ----------

	Subject: Re: [Radiance-general] Fwd: errors from hdrgen
	Date: Friday 11 June 2004 14:17
	From: Martin Matusiak <alex at juventuz.net>
	To: Radiance general discussion <radiance-general at radiance-online.org>

	> I hdr'ed all ouf the 13 images in one go, and apart for some 'poor
	> convergence' (orders 1, 3, 4 and 5) warnings, it worked fine. There is
	> no apparent distortion.

	I repeated the process using the manual mode of the camera rather than
	aperture priority. Again 13 images (same room, scene was a bit different as
	I
	eliminated the sky in the framing) and I was able to compute a hdr. But the
	alignment problem still persists, I use the -a switch to turn it off.

	Later I took a couple more images and used the calibration data to compute a
	hdr and read the luminance values off it. It turns out that those are
	somewhat accurate so that's a good sign!

	However, I'm still not quite satisfied. Obviously, the calibration procedure
	is meant to give a most accurate static description of the camera, but I
	used
	the camera's automatic whitebalance correction, so that's a variable. My
	question is a complete novice one: how does the whitebalance affect the
	luminance? What can I do to eliminate this variable (if it is significant).

	Martin

	-------------------------------------------------------

	------------------------------

	Message: 4
	Date: Fri, 11 Jun 2004 14:51:26 +0100
	From: "Anthony J. Farrell" <anthony.farrell at dit.ie>
	Subject: [Radiance-general] Prismatic glazing in radiance PMAP
	To: radiance-general at radiance-online.org
	Message-ID: <OJEGILOIGGNAEAODNHIICEEGCDAA.anthony.farrell at dit.ie>
	Content-Type: text/plain; charset=iso-8859-1

	Hi,

	I am trying to model a simple sheet of prismatic glazing, but am unclear of
	the dimension variable set out in the PMAP user manual for the prism
	command.

	Could anyone please forward me a drawing or sketch of what this command is
	based?

	Kind regards,

	Anthony

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	------------------------------

	Message: 5
	Date: Fri, 11 Jun 2004 08:09:17 -0700
	From: Greg Ward <gward at lmi.net>
	Subject: Re: [Radiance-general] Fwd: errors from hdrgen
	To: Radiance general discussion <radiance-general at radiance-online.org>
	Message-ID: <4EE8BCAC-BBB9-11D8-BDAA-000A95BB392A at lmi.net>
	Content-Type: text/plain; charset=US-ASCII; format=flowed

	Hi Martin,

	I believe that hdrgen isn't coming up with a good response function for
	your camera with this scene, probably due to the strong color cast of
	the walls.  Since hdrgen (and Photosphere) compute the responses for
	each of the RGB channels, using a lot of colorful patch samples can
	skew the result.  I've never seen such an extreme example before,
	though -- most walls are off-white so this hadn't come up.  Come to
	think of it, the tendency of cameras to super-saturate their colors
	could spell trouble in such cases, and I probably should modify my
	algorithm to avoid colorful patch samples.

	Thanks for the image set -- I'll run some experiments on my end to see
	if I can improve on this.  It is important to fix the white balance
	whenever you take an HDR sequence, as the camera in auto white mode
	will alter the coefficients between exposures otherwise, making it
	impossible to get a consistent result.

	-Greg

	> From: Martin Matusiak <alex at juventuz.net>
	> Date: June 11, 2004 5:17:29 AM PDT
	>
	>> I hdr'ed all ouf the 13 images in one go, and apart for some 'poor
	>> convergence' (orders 1, 3, 4 and 5) warnings, it worked fine. There is
	>> no apparent distortion.
	>
	> I repeated the process using the manual mode of the camera rather than
	> aperture priority. Again 13 images (same room, scene was a bit
	> different as I
	> eliminated the sky in the framing) and I was able to compute a hdr.
	> But the
	> alignment problem still persists, I use the -a switch to turn it off.
	>
	> Later I took a couple more images and used the calibration data to
	> compute a
	> hdr and read the luminance values off it. It turns out that those are
	> somewhat accurate so that's a good sign!
	>
	> However, I'm still not quite satisfied. Obviously, the calibration
	> procedure
	> is meant to give a most accurate static description of the camera, but
	> I used
	> the camera's automatic whitebalance correction, so that's a variable.
	> My
	> question is a complete novice one: how does the whitebalance affect the
	> luminance? What can I do to eliminate this variable (if it is
	> significant).
	>
	> Martin

	------------------------------

	Message: 6
	Date: Fri, 11 Jun 2004 09:18:46 -0700
	From: Greg Ward <gward at lmi.net>
	Subject: [Radiance-general] Re: Fwd: errors from hdrgen
	To: Radiance general discussion <radiance-general at radiance-online.org>
	Message-ID: <03936172-BBC3-11D8-992A-000A95BB392A at lmi.net>
	Content-Type: text/plain; charset=US-ASCII; format=flowed

	Hi again.

	Well, I played around with limiting the saturation on patches, and it
	only seems to make matters worse; I'm not sure why.  I think it's
	because you don't have enough unsaturated pixels in your scene for it
	to work, but I'll have to perform some more experiments to determine
	that for certain.  For now, you'll just have to find a more "neutral"
	scene to perform your calibration on, then save the response function
	and reuse it for other scenes, which is what I've been doing.

	-Greg

	> From: Martin Matusiak <alex at juventuz.net>
	> Date: June 11, 2004 5:21:55 AM PDT
	>
	> I forgot to mention that my "cvs build" of hdrgen is from last week,
	> so there
	> could have been changes from the version you have.
	>
	> Martin

	------------------------------

	Message: 7
	Date: Fri, 11 Jun 2004 21:11:56 +0200
	From: Roland Schregle <ganjatron at gmx.net>
	Subject: Re: [Radiance-general] Prismatic glazing in radiance PMAP
	To: Radiance general discussion <radiance-general at radiance-online.org>
	Message-ID: <40CA03FC.6010504 at gmx.net>
	Content-Type: text/plain; charset=us-ascii; format=flowed

	Anthony J. Farrell wrote:
	> Hi,
	>
	> I am trying to model a simple sheet of prismatic glazing, but am unclear
	of
	> the dimension variable set out in the PMAP user manual for the prism
	> command.

	Dimension variable? If you're referring to the -ds parameter, that
	affects the resolution with which the light source surfaces are sampled
	during photon emission. Are you referring to the prism material or the
	genprism command?

	--
	Roland Schregle
	PhD candidate, Fraunhofer Institute for Solar Energy Systems
	RADIANCE Photon Map page: www.ise.fhg.de/radiance/photon-map

	END OF LINE. (MCP)

	------------------------------

	Message: 8
	Date: Fri, 11 Jun 2004 16:03:42 -0400
	From: "Martin Moeck" <MMoeck at engr.psu.edu>
	Subject: RE: [Radiance-general] Prismatic glazing in radiance PMAP
	To: "Radiance general discussion"
	        <radiance-general at radiance-online.org>
	Message-ID:
	        <84F05BA9118BBD4A8FC6409808CE266C113A1F at ENGRMAIL2.engr.psu.edu>
	Content-Type: text/plain; charset="utf-8"

	Are there any validations of pmap? If desired, I can make measured data
	available for some prismatic  glazings as shown at www.siteco.de. See
	http://www.siteco.de/products/tageslichtsysteme/?currency=EUR&lang=en&javasc
	ript=true  Click on "large panel prism systems".

	Martin, Penn State

	        -----Original Message-----
	        From: Roland Schregle [mailto:ganjatron at gmx.net]
	        Sent: Fri 6/11/2004 3:11 PM
	        To: Radiance general discussion
	        Cc:
	        Subject: Re: [Radiance-general] Prismatic glazing in radiance PMAP

	        Anthony J. Farrell wrote:
	        > Hi,
	        >
	        > I am trying to model a simple sheet of prismatic glazing, but am unclear
	of
	        > the dimension variable set out in the PMAP user manual for the prism
	        > command.

	        Dimension variable? If you're referring to the -ds parameter, that
	        affects the resolution with which the light source surfaces are sampled
	        during photon emission. Are you referring to the prism material or the
	        genprism command?

	        --
	        Roland Schregle
	        PhD candidate, Fraunhofer Institute for Solar Energy Systems
	        RADIANCE Photon Map page: www.ise.fhg.de/radiance/photon-map

	        END OF LINE. (MCP)

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