Comparison of indirect and direct illumination . u. or i. roRM 3 DIRECT S-OBSERVEDPlane 5 ftSTATION A 3 1 2 3 4 5 6 7 8 9 10 11 in. c D E 0. 52 U. CF I. 6. 6. rCHM 3 27 VI. THEORY AND CALCULATION OF A DIRECT LIGHTING SYSTEM To get the normal illumination at any given point the oandle powerin the proper diredtion mus
Comparison of indirect and direct illumination . u. or i. roRM 3 DIRECT S-OBSERVEDPlane 5 ftSTATION A 3 1 2 3 4 5 6 7 8 9 10 11 in. c D E 0. 52 U. CF I. 6. 6. rCHM 3 27 VI. THEORY AND CALCULATION OF A DIRECT LIGHTING SYSTEM To get the normal illumination at any given point the oandle powerin the proper diredtion must be divided by the square of the distance to thepoint illuminated. If the surface is at right angles to the direction oflight, the value of illumination obtained must be multiplied by a reductionfactor, taking into account the angle at which the rays strike. Referring tothe diagram below, a beam of light coming in the direction OD falls upon a plane AB, illuminating it with an intensity of one foot-candle. Then theillumination on the plane AC,which intercepts the same amount of light asAB, would be less than one foot-candle (as the light is spread over a largerarea), in the ratio of AB to AC, which is the cosine of the angle ODF. Thusthe intensity on any plane at a given point will be C h
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttheses, bookyear1912
