[Radiance-general] visualize position index

[Ji Zhang]

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

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
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