displays

radiance-general
1

Hello All,

I have used genbox to create a....box (obviously) and now want to change one side of it to act as the front of a display.(Im not interested in the detail of the display case, a simple box will do)
I know how to replace one of the polygons with a different material type but what does anyone recommend to use? I dont require the display to show any pictures, i just want it to have a uniform white light emitting from one side of 400 nits. Should i use an illum surface? How can i ensure it has the brightness i require??

Your reply email (below) and attachments to yuni has helped me some greg, i can now add pictures if i so wish, but not sure if it helps me with my above questions

my box is below, although im sure i havent needed to put it in.

thanks in advance

chris

···

-----Original Message-----
From: [email protected] on behalf of Gregory J. Ward
Sent: Tue 7/25/2006 6:39 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] glare on monitor screen

Hi Yuni,

Here is a description for an HP LCD monitor we measured at LBNL for
the New York Times (work sponsored by NYSERDA). You can substitute
any 1024x768 screen shot you like for "VDTdisp.pic". Make sure the
maximum value is <= 1.0.

As for glare analysis, I don't know how you mean to associate
discomfort glare with a VDT. Perhaps you are thinking of veiling
glare -- reflections from the screen that reduce visibility?

-Greg

void plastic grey
0
0
5 .5 .5 .5 0 0

grey polygon display.1540
0
0
12
               2.57 7 2
               2.57 7 2.09
                2.4 7 2.09
                2.4 7 2

grey polygon display.4620
0
0
12
                2.4 7 2.09
                2.4 7.05 2.09
                2.4 7.05 2
                2.4 7 2

grey polygon display.2310
0
0
12
                2.4 7.05 2
               2.57 7.05 2
               2.57 7 2
                2.4 7 2

grey polygon display.3267
0
0
12
               2.57 7.05 2
                2.4 7.05 2
                2.4 7.05 2.09
               2.57 7.05 2.09

grey polygon display.5137
0
0
12
               2.57 7 2.09
               2.57 7 2
               2.57 7.05 2
               2.57 7.05 2.09

grey polygon display.6457
0
0
12
                2.4 7.05 2.09
                2.4 7 2.09
               2.57 7 2.09
               2.57 7.05 2.09

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2

Hi Chris,

You can use a simple "light" type, using 400/179 for the radiance value:

void light display_surface
0
3 2.2346 2.2346 2.2346

Then substitute this material for the appropriate face. If you don't expect the display to illuminate surface more than a certain distance away -- say 20 in your world units, you can use a glow for higher efficiency

void glow display_surface
0
4 2.2346 2.2346 2.2346 20

Hope this helps.
-Greg

···

From: "Chris Foster" <[email protected]>
Date: August 2, 2006 6:47:42 AM EDT
Hello All,

I have used genbox to create a....box (obviously) and now want to change one side of it to act as the front of a display.(Im not interested in the detail of the display case, a simple box will do)
I know how to replace one of the polygons with a different material type but what does anyone recommend to use? I dont require the display to show any pictures, i just want it to have a uniform white light emitting from one side of 400 nits. Should i use an illum surface? How can i ensure it has the brightness i require??

Your reply email (below) and attachments to yuni has helped me some greg, i can now add pictures if i so wish, but not sure if it helps me with my above questions

my box is below, although im sure i havent needed to put it in.

thanks in advance

chris

3

hi greg

thanks alot, that has answered my questions, your a big help as always.

chris

···

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
                   Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

4

hi all

anyone who feels the need can answer this question but i think greg might know the answer after readin one of his previous emails.

greg, you including an email with a file for a LCD display on an email to yuni previously, with a hack in it to give the glowing screen some reflectance...helps but i need some more , please!!

i want to shine light onto an ON display and measure the combined light reflecting off of it. this has to include the reflected light and the transmitted light of the display itself. how do i achieve this?

im comfortable with using rcalc|rtrace|rcalc and bgraph so i dont need any help there. i require some assistance with the materials for the display. i currently have the material LIGHT emitting from one side of the display, would it be wise to put in GLASS in front of this light? can i model this glass so that it transmittes the light coming from behind it (from the display) and at the same time reflects the light incident on it from the front, from the spotlights.

hope that was easy enough to follow. i feel brtd func would be more appropiate than glass but would appreciate any one's thoughts.

thanks in advance

chris

···

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
                   Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

5

Hi Chris.

Because no one answered this so far I will step in with
my limited knowledge and experience about materials:

i want to shine light onto an ON display and measure the
combined light reflecting off of it. this has to include
the reflected light and the transmitted light of the display
itself. how do i achieve this?

im comfortable with using rcalc|rtrace|rcalc and bgraph so
i dont need any help there. i require some assistance with
the materials for the display. i currently have the material
LIGHT emitting from one side of the display, would it be wise
to put in GLASS in front of this light?

You definitively want to combine your light material with
something in front of it as "light" (or "glow" as far as
it matters) has no reflectance and no transmittance. Nothing
will reflect off a "light" and nothing will shine through.
The 'shine through' is what "illum" was designed for.

'glass' as a reflector would certainly be possible but it
is not the best choice. Even if there are still glass-screened
displays around they would probably be treated with some
sort of coating to avoid reflections which the 'glass' material
does not account for.

I'd try a 'trans' material with a very high transmittance
(similar to glass) and nearly no diffuse component. This
gives you the possibility to tweak the reflectance to something
similar to a LCD screen. I don't know what their physical
reflectance value is in reality I just know that I can't read
my screen at work sometimes because I've the window in my
back.

can i model this glass so that it transmittes the light
coming from behind it (from the display) and at the same
time reflects the light incident on it from the front,
from the spotlights.

Reading the above you might just want to simulate the
glare effect of a point light source on your screen.
Then a 'mirror' type material may be your friend. Just
use your 'light' material as modifier of the mirror for
non source rays:

void light display_light
0
3 2.23 2.23 2.23

void mirror display_surface
1 display_light
0
3 0.8 0.8 0.8

(example for something with 80 % reflectance).

You can't change the surface finish, though.

Thomas

···

On 9 Aug 2006, at 10:31, Chris Foster wrote:

6

Thanks to Thomas for offering that thoughtful reply. I'm a little swamped at the moment... The files I gave to Yuni under the subject "glare on monitor screen" a couple weeks ago are the best I have to offer at the moment. Note that I used a "mixfunc" type to get the diffuse, specular, and emission to happen together in one material. The "glass" isn't really appropriate, for the reasons Thomas mentioned among others.

-Greg

···

From: "Chris Foster" <[email protected]>
Date: August 9, 2006 1:31:14 AM PDT

hi all

anyone who feels the need can answer this question but i think greg might know the answer after readin one of his previous emails.

greg, you including an email with a file for a LCD display on an email to yuni previously, with a hack in it to give the glowing screen some reflectance...helps but i need some more , please!!

i want to shine light onto an ON display and measure the combined light reflecting off of it. this has to include the reflected light and the transmitted light of the display itself. how do i achieve this?

im comfortable with using rcalc|rtrace|rcalc and bgraph so i dont need any help there. i require some assistance with the materials for the display. i currently have the material LIGHT emitting from one side of the display, would it be wise to put in GLASS in front of this light? can i model this glass so that it transmittes the light coming from behind it (from the display) and at the same time reflects the light incident on it from the front, from the spotlights.

hope that was easy enough to follow. i feel brtd func would be more appropiate than glass but would appreciate any one's thoughts.

thanks in advance

chris