Proposal for an alternative procedure for glare assessment: a new temporal approach of viewing direction

Abstract Glare can be considered as one of the most complex aspects of the daylighting evaluation process due to its subjective nature and the limitations of$ usual forms of assessment. Although the glare is a subjective response, many indices have been developed to quantify this phenomenon. Existing glare assessment models assume that occupants' view direction fixed on the task and ignore the dynamic nature of vision. This paper presents the impact of the time in the calculation of DGI. A teacher was adopted as a dynamic subject who has several view directions. The procedures adopted included the use of a video camera, software for video editing, HDR images and post processing data through photometric measurement system called Photolux. With DGI data for each direction of view, in each position, in all scenarios and the time in which the teacher looked at each direction, estimated through the video, two weights were held: DGItd (time spent in each direction) and DGItp (time spent in each position) resulting in a total index of the room. The results showed that the total index of the room was lower than those values obtained from Photolux in most cases, reaching reductions of up to 30% for a given situation. This study reinforces the importance of incorporating the temporal condition in evaluating glare.

摘要 眩光因其主观特性与常规评估手段的局限性，可被视为采光评估过程中最为复杂的环节之一。尽管眩光属于主观视觉反应，但学界已开发出诸多量化该现象的评价指标。现有眩光评估模型均假定使用者的视线固定于作业对象，且忽略了视觉系统的动态特性。本文探讨了时间因素在采光眩光指数（Daylight Glare Index，DGI）计算中的影响。本研究选取一名教师作为动态测试主体，其具备多组视线方向。本次研究采用的实验流程包括：使用摄像机、视频编辑软件、高动态范围（High Dynamic Range，HDR）图像，以及通过名为Photolux的光度测量系统完成数据后处理。基于通过视频估算得到的教师注视各方向的时长，以及各场景下各位置对应各视线方向的DGI数据，本研究设置了两类权重：分别为对应单方向注视时长的DGItd（各方向注视时长）与对应单位置总注视时长的DGItp（各位置总注视时长），最终得到房间整体眩光总指数。研究结果显示，在大多数场景下，房间整体眩光总指数均低于Photolux系统的测算结果，部分场景下降幅可达30%。本研究进一步证实了在眩光评估中纳入时间维度的重要性。