An approach for definition and evaluation of shadow characteristics as a design criterion occured under artificial lighting

One of the lighting design criteria is the attributes of shadows occurred in architectural spaces. So as shadow quality can compose rich visions, it can make the visual perception be tiring and captious, too. At the present day, there are proper approachments for determining the lightness-darkness quality of self shadows. But, guiding data about the attributes and determination of cast shadows is limited.The aim of this study is to develop a method to determine the shadow quality and to grade the harshness-softness and lightness-darkness of shadow. For this purpose, the studies about shadow quality is investigated and evaluated. Which factors how change the shadow quality is investigated by a lighting software. In this study, different conditions such as luminaire, object, reflectance of surfaces that affect the shadow are taken on. Thereby, detailed information is obtained about shadow characteristics.To determine the harshness-softness quality of a shadow by the ratio of umbra area to total shadow area; lightness-darkness quality related to the luminance of umbra and the luminance of the immediate bordering area without shadow is adjudged. It is researced how can be determined the the two feature of cast shadow by investigation the relation between direct and total illuminance and shadow factor distribution. To confirm the physical size and luminance of umbra and area without shadow is seen inadequate for shadow determination. So, the size and the luminance perception of a shadow is investigated. For the aim of evaluating the shadow features by visual perception, a 1/1 scaled mock-up room was generated. To obtain different shadow features, four different types, total 16 luminaires are used. A mock-up room which has the same fetures of 1/1 scaled mock-up room has been created in DIALux Lighting Software. Firstly, various scenarios have been constituted by the variants and the change of the shadow features has been displayed related to this scenarios.Two staged experimental study has been implemented to designate the harshness-softness attribute of a shadow. Shadow samples whose size and harshness-softness attribute is diffrent are consisted by changing the size and position of the object that occurs shadow. Visual evaluation of these shadow samples are done by computer. Firstly, the umbra area related to total shadow area is asked by percentage. By the end of these total shadow area perception evaluations, formulas to confirm the harshness-softness feature has been developed. In the second stage of this experimental study, subjects denoted the harshness-softness impressions about these shadow samples.A method related to brightness differance of umbra luminance and shadow bordering area luminance is developed to determine the lightness-darkness feature of a shadow. Harshness-softness dimension is graded in terms of experimental study related to harshness-softness impression and the lightness-darkness dimension is graded in terms of developed method related on brightness difference.The lighting scenarios that are composed by lighting software for one and two users are ordered in 1/1 scaled mock-up room, too. Inquries is done to evaluate the shadows occurred by this lighting scenarios. The subjects are wanted to denote lightness-darkness and harshness-softness impressions numerically about the shadows occurred by different scenarios. Inquiry results are coherent by the shadow degrees of developed method.The general impressions about the lighting scenarios and the degrees of the shadows determined by the developed method was compared. As a result of this comparison, the lighting scenarios which are accepted positive by the subjects are confirmed. Consequently, for lighting design, guiding principles for providing the requirements in terms of shadow criterion is displayed.