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.\" RCSid $Id: evalglare.1,v 1.1 2015/08/12 23:07:59 greg Exp $ |
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.TH EVALGLARE 1 7/30/15 RADIANCE |
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.SH NAME |
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evalglare \- determines and evaluates glare sources within a 180 degree fisheye HDR image |
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.SH SYNOPSIS |
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.PP |
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.nh |
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.B evalglare |
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[ |
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.BI \-s |
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] |
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[ |
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.BI \-y |
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] |
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[ |
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.BI \-Y \ value |
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] |
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[ |
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.BI \-B " angle" |
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] |
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[ |
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.BI \-b " factor" |
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] |
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[ |
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.BI \-c " checkfile" |
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] |
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[ |
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.BI \-t " xpos ypos angle" |
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] |
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[ |
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.BI \-T " xpos ypos angle" |
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] |
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[ \-d ] |
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[ |
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.BI \-r " angle" |
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] |
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[ |
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.BI \-i " Ev" |
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] |
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[ |
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.BI \-I " Ev yfill_max y_fill_min" |
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] |
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[ |
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.BI \-v |
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] |
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[ |
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.BI \-V |
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] |
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[ |
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.BI \-g " type" |
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] |
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[ |
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.BI \-G " type" |
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] |
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[ |
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.BI \-u " r g b" |
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] |
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[ |
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.BI \-vf " viewfile" |
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] |
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[ |
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.BI \-vt t |
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] |
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[ |
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.BI \-vv " vertangle" |
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] |
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[ |
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.BI \-vh " horzangle" |
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] |
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.RI [ hdrfile ] |
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.hy |
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.SH DESCRIPTION |
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.PP |
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.B Evalglare |
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determines and evaluates glare sources within a 180 degree fisheye |
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image, given in the RADIANCE image format (.pic or .hdr). If |
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.I hdrfile |
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is not given as an argument, the standard input is read. The image |
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should be rendered as fisheye (e.g. using the |
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.BI \-vt a |
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or |
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.BI \-vt h |
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option) using 180 degrees for the horizontal and vertical view angle |
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.RB ( -vv |
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.IR 180 , |
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.B -vh |
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.IR 180 ). |
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The recommended size of images input to |
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.B evalglare |
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is 1000x1000 pixels; the computations become very long when the image |
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is more than 1200x1200 pixels. |
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.PP |
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The calculation of glare proceeds in two steps: |
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.IP 1. 3em |
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In the first step, the program uses a given threshold |
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to determine all glare sources. Three different threshold methods are |
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implemented. The recommended method is to define a task area by |
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.B \-t |
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or |
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.B \-T |
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option. The average luminance of the task area is calculated. Each |
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pixel exceeding this value multiplied by the |
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.B \-b |
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factor, default 5, is treated as a potential glare source. The other |
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two methods are described below, see |
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.BR \-b . |
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.IP 2. |
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In the second step, the program tries to merge glare source pixels to |
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one glare source, when they are placed nearby each other. This |
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merging is performed between search areas, given by an opening angle |
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.BR \-r , |
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default 0.2 radians. If a check file is written, |
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.B \-c |
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.IR fname , |
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the detected glare sources will be colored, each with a different |
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color, and the rest of the image will be set to gray. The luminance values |
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of all pixels are kept to the initial value. The color is chosen by |
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chance, no significance is given by the color. To enable unform |
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coloring of all glare sources, the |
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.B \-u |
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option can be used. Luminance |
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peaks can be extracted to separate glare sources by using the |
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.B \-y |
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or |
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.BI \-Y " value" |
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option. The default value |
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.B \-y |
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is 50,000 cd/m2, which can be changed by using the |
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.B \-Y |
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value. A smoothing option, |
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.BR \-s , |
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counts initial non-glare source pixels to glare sources, when they are |
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surrounded by a glare source. |
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.PP |
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The program calculates the daylight glare probability (DGP) as well as |
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other glare indices (DGI, UGR, VCP, CGI) and writes them to the |
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standard output. The DGP describes the fraction of persons disturbed |
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caused by glare from daylight as a number from 0 to 1, where 0 is |
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no-one disturbed and 1 is everyone. Values lower than 0.2 are out of |
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the range of the user assessment tests which the program is based on |
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and should be interpreted carefully. A low light correction is |
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applied to the DGP when the vertical illumiance is lower than 500 lux. |
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By the use of |
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.B \-g |
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or |
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.B \-G |
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.\" Citation? |
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the field of view is cut according the the definition of Guth. |
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The option |
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.B \-B |
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angle (in radians) calculates the average luminance of a |
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horizontal band. In the case of non-180 degree images, an external |
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measured illuminance value can be provided by using the |
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.B \-i |
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or |
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.B \-I |
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option. The use of the |
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.B \-I |
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option enables the filling up of images, which are horizontally cut. |
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If the |
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option |
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.B \-d |
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is used, all found glare sources and their position, size, and |
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luminance values are printed to the standard output, too. The last |
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line gives following values: (1) DGP, (2) average luminance of image, |
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(3) vertical eye illuminance, (4) background luminance, (5) direct |
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vertical eye illuminance, (6) DGI, (7) UGR, (8) VCP, (9) CGI, (10) |
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average luminance of all glare sources, (11) sum of solid angles of |
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all glare sources, (12) Veiling luminance (disability glare), (13) |
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x-direction of glare source, (14) y-direction of glare source, (15) |
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z-direction of glare source, and (16) band luminance. |
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.SH OPTIONS |
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.TP |
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.BI \-B \ angle |
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Calculate average luminance of a horizontal band. The angle is in |
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radians. This calculation does not affect glare source detection. |
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Output only when using the |
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.B \-d |
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option. |
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.TP |
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.BI \-b \ factor |
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Threshold factor; if factor is over 100, it is used as constant threshold in |
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cd/m2, regardless if a task position is given or not if |
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factor is less than or equal to 100 and a task position is given, this |
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factor multiplied by the average task luminance will be used as |
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threshold for detecting the glare sources if factor is less than or |
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equal to 100 and no task position is given, this factor multiplied by |
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the average luminance in the entire picture will be used as threshold |
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for detecting the glare sources, default\ 5. |
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.TP |
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.BI \-c \ fname |
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writes a checkfile in the RADIANCE picture format |
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.TP |
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.B \-d |
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enables detailed output (default: disabled) |
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.TP |
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.BI \-g \ type |
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cut field of view according to Guth, write checkfile specified by |
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.B \-c |
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and exit without any glare evaluation. Type 1: total field of view. |
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Type 2: field of view seen by both eyes |
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.TP |
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.BI \-G \ type |
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Cut the field of view according to Guth, perform glare evaluation. |
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Type 1: total field of view. Type 2: field of view seen by both eyes |
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.TP |
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.BI \-i \ Ev |
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The vertical illuminance is measured externally. This value will be |
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used for calculating the dgp. |
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.TP |
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.BI \-I \ Ev \ y_max \ y_min |
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The vertical illuminance is measured externally. |
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This value will be used for calculating the DGP. |
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Below |
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.I y_min |
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and above |
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.IR y_max , |
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the picture is filled up by the last known value. This option should |
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be used, when the provided picture is cut horizontally. |
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.TP |
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.BI \-r \ angle |
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search radius (angle in radians) between pixels, where |
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.B evalglare |
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tries |
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to merge glare source pixels to the same glare source (default value: |
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0.2 radians) |
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.TP |
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.B \-s |
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enables smoothing function (default: disabled) |
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.TP |
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.BI \-t \ xpos \ ypos \ angle |
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definition of task position in x and y coordinates, and its opening |
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angle in radians |
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.TP |
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.BI \-T \ xpos \ ypos \ angle |
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same as |
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.BR \-t , |
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except that the task area is colored bluish in the checkfile |
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.TP |
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.BI \-u \ r \ g \ b |
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color glare sources uniformly when writing check file (implies |
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.B \-c |
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option). Color given in r g b. |
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.TP |
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.B \-v |
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show version of |
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.B evalglare |
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and exit |
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.TP |
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.B \-V |
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Just calculate the vertical illuminance and exit |
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.TP |
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.B \-x |
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disable peak extraction |
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.TP |
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.B \-y |
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enables peak extraction (default: enabled) |
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.TP |
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.BI \-Y \ value |
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enables peak extraction with |
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.I value |
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as threshold for extracted peaks. |
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.PP |
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.I "If the view settings in the image file" |
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are missing or are not valid (e.g. after the use of |
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.BR pcompos "(1) or " pcomb (1)), |
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the view options can be set by command line options. If view options |
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are set on the command line, view options in the image file header are |
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ignored. The view options are implemented according to the RADIANCE |
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definition; please read the |
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.BR rpict (1) |
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man page for details. |
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.sp |
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.TP |
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.BI \-vt t |
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Set view type to t (for fisheye views, please use |
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.BI \-vt \ a |
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or |
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.BI \-vt \ h |
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preferably) |
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.TP |
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.BI \-vf \ viewfile |
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Get view parameters from file |
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.TP |
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.BI \-vv \ val |
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Set the view vertical size to val |
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.TP |
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.BI \-vh \ val |
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Set the view horizontal size to |
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.I val |
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.SH AUTHOR |
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Jan Wienold. |
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.SH SEE ALSO |
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.BR rpict (1) |
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.SH REFERENCES |
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.B Evalglare |
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is based on the studies by J. Christoffersen and J. |
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Wienold (see \*(lqEvaluation methods and development of a new glare |
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prediction model for daylight environments with the use of CCD cameras |
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and RADIANCE,\*(rq |
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.IR "Energy and Buildings 38" , |
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2006, pp. 743\-757, doi:10.1016/j.enbuild.2006.03.017. More |
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details can be also found in following dissertation: J. Wienold, |
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.IR "Daylight glare in offices" , |
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Fraunhofer IRB, 2010, available online at |
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.nh |
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<http://publica.fraunhofer.de/dokumente/N-141457.html>. |
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.hy |
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.SH ACKNOWLEDGEMENTS |
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The evalglare program was originally developed by Jan Wienold at the |
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Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany. It |
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is being further developed and maintained by the same author at EPFL, |
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Lausanne, Switzerland. |
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.PP |
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The author would like to thank C. Reetz for his generous help and his |
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support of providing libraries for the program. The EU Commission |
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supported this work as part of the EU project \*(lqEnergy and Comfort |
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Control for Building management systems\*(rq (ECCO-Build, Contract |
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ENK6-CT-2002-00656). |
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.PP |
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German Research Foundation (DFG) contract WI 1304/7-2 supported the research |
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for the extension of evalglare for low light scenes. |