[Radiance-general] visualize position index

[Jan Wienold]

Dear Ji,

there is an undocumented option in evalglare (-p), which replaces the 
luminance values to the position-index values. So you can directly 
generate an image just with the position index with just one command line...
You have to use evalglare in the normal manner (-> feed in image and 
specify output image. The content of the input image doesn't matter, 
just the header options must be correct.)

example: evalglare -p -c position_index.hdr  inputimage.hdr

Good luck,

Jan



On 04/29/2012 08:15 PM, Ji Zhang wrote:
> Dear Radiance experts,
>
> Learning glare related analysis, I write a .cal file to define the
> position index for every point on the sky in relation to a given view
> vector based on the position index formula. I also prepared a batch
> file to visualize it.
>
> However, the image I got is not a circular fisheye one and the upper
> half of the pattern doesn't seem to resemble what appeared on page 753
> in Dr Wienold and Dr Christoffersen's paper:
> Wienold, J., & Christoffersen, J. (2006). Evaluation methods and
> development of a new glare prediction model for daylight environments
> with the use of CCD cameras. Energy and Buildings, 38(7), 743-757.
>
> Images are shown here:
> http://episode-hopezh.blogspot.com/2012/04/viz-position-index.html
>
> The .cal and batch files can be downloaded from:
> https://sites.google.com/site/episodehopezh/files/viz_sg.rar?attredirects=0&d=1
> <https://sites.google.com/site/episodehopezh/files/viz_sg.rar?attredirects=0&d=1>
>
> Two folders are included, one for visualizing the position index and
> the other one for visualizing the inverted position index.
>
> The view is a horizontal one towards due south. The image extracted
> from Dr Wienold and Dr Christoffersen's paper is also included as a
> reference.
>
> Can you kindly take a look of the .cal and batch file and advise me on:
> 1) why I can't get a circular fisheye image (I assume there's simple
> rookie error in the script...)?
> 2) whether the position index pattern as visualized is correct?
> 3) how to convert the image into one using position index value as
> color legend?
>
>
> Would greatly appreciate if Dr Wienold can kindly provide some
> suggestions!
>
> Thank you very much in advance!
>
> - Ji
>
>
>
>


-- 
Dr.-Ing. Jan Wienold
Head of Team Passive Systems and Daylighting
Fraunhofer-Institut für Solare Energiesysteme
Thermal Systems and Buildings
Heidenhofstr. 2, 79110 Freiburg, Germany
Phone: +49(0)761 4588 5133 Fax:+49(0)761 4588 9133
jan.wienold at ise.fraunhofer.de
http://www.ise.fraunhofer.de

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