Hi all,
I was trying to run glare analysis via Desktop Radiance for glazing with 2
different VLT:
a) VLT = 30
b) VLT = 60
The type used for these glazing are kept as default --> "glass".
1) For the first analysis, I have adjusted the exposure for both images in
order to reflect more accurate visual view showing the differences between
clear and darker glass.
The glare index via UGR shows:
a) VLT 30 = 36
b) VLT 60 = 44
2) For the second analysis, on top adjusting the exposure, I have also
used "pcond -h" on the images.
The glare index via UGR shows:
a) VLT 30 = 0
b) VLT 60 = 0
Looking at the comparison of the results above, I am not sure whether
"pcond -h" should be used prior to glare analysis. Should the glare
analysis be done on raw images without "pcond -h"? ......although it was
stated that "pcond -h" will create a view that mimic human responses.
Would really appreciate any sharing or help on this!
Thanks in advance!
Cheers,
Ann
If you are not the email's intended recipient, kindly inform the sender
and delete it.
The email may contain confidential information which should not be
retained, nor disclosed to another individual.
Hi Ann,
first, Desktop Radiance is unsupported and has not been updated for ages. Avoid using it, there are better, supported software around based on current versions of Radiance.
Second, glare analysis is based on the pixel values. Thus I would not adjust anything in images that are supposed to be used for analysis. To make sure that you are working with original pixel values, use pcomb -o : pcomb -o filtered.hdr > raw.hdr and use raw.hdr as input for all your analysis.
But: Images generated by pcond -h can NOT be used for such analysis, and as far as I know, there is no way to revert the changes made to the pixel values. The idea behind pcond -h is to give a visual impression what an scene would be perceived like by a human observer, which requires changes to the pixel values beyond exposure settings.
Cheers, Lars.
I would suggest it is good practice when using pcond -h to save the image as a low dynamic range file rather than .pic or .hdr, since pcond is meant to create nice looking pictures, not useful data.
e.g.
pcond -h image.hdr | ra_ppm | convert ppm:- image.jpg
That way you never mix up .pic or .hdr files that contain adjusted and incorrect data values.
···
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
THat's a good idea, Chris. I usually make it a habit to name my tone mapped .hdr files with a suffix that indicates to me that it's been run through the pixel wringer, and of course the header will also indicate that the image is the product of pond, but your method eliminates the middle man. =)
- Rob
···
On Feb 27, 2013, at 7:31 AM, Christopher Rush <[email protected]> wrote:
I would suggest it is good practice when using pcond -h to save the image as a low dynamic range file rather than .pic or .hdr, since pcond is meant to create nice looking pictures, not useful data.
e.g.
pcond -h image.hdr | ra_ppm | convert ppm:- image.jpg
That way you never mix up .pic or .hdr files that contain adjusted and incorrect data values.
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
That's a good practice, and one I follow as well. Since pcond output is meant to be sent to a printer or low dynamic-range display device, converting it to a lower bit-depth at the same time makes perfect sense. Some of the programs that convert to such formats have built-in tone-mappers that are similar to pcond but less sophisticated and faster. See the ra_bmp '-e' option and the normtiff command.
-Greg
···
From: Christopher Rush <[email protected]>
Date: February 27, 2013 6:31:58 AM PST
I would suggest it is good practice when using pcond -h to save the image as a low dynamic range file rather than .pic or .hdr, since pcond is meant to create nice looking pictures, not useful data.
e.g.
pcond -h image.hdr | ra_ppm | convert ppm:- image.jpg
That way you never mix up .pic or .hdr files that contain adjusted and incorrect data values.
----------
From: "Sim Swee Ling Annie" <[email protected]>
Date: February 27, 2013 1:25:43 AM PST
Hi all,
I was trying to run glare analysis via Desktop Radiance for glazing with 2 different VLT:
a) VLT = 30
b) VLT = 60
The type used for these glazing are kept as default --> "glass".
1) For the first analysis, I have adjusted the exposure for both images in order to reflect more accurate visual view showing the differences between clear and darker glass.
The glare index via UGR shows:
a) VLT 30 = 36
b) VLT 60 = 44
2) For the second analysis, on top adjusting the exposure, I have also used "pcond -h" on the images.
The glare index via UGR shows:
a) VLT 30 = 0
b) VLT 60 = 0
Looking at the comparison of the results above, I am not sure whether "pcond -h" should be used prior to glare analysis. Should the glare analysis be done on raw images without "pcond -h"? ......although it was stated that "pcond -h" will create a view that mimic human responses.
Would really appreciate any sharing or help on this!
Thanks in advance!
Cheers,
Ann
Thanks all for the advise & help!
Understand now that pcond -h is mainly for visual purpose. Hence, does
that also meant the exposure settings should not be adjusted (for
comparison of clear and darker glass)?
I am currently using the Desktop Radiance via Ecotect plug-in. Is there a
recommendation to which free tool available I can use that still allow me
to do glare analysis for an Ecotect model with better accuracy?
Have downloaded "radiance-4.2.a-win32.exe" but not too sure where to
start... What is the application difference with the Ecotect desktop
radiance plug-in I am using now. Am I supposed to generate an image via
Ecotect and use command prompt to run the analysis or there is another
tool I would need to download?
Cheers,
Ann
If you are not the email's intended recipient, kindly inform the sender
and delete it.
The email may contain confidential information which should not be
retained, nor disclosed to another individual.