The International Daylight Measurement Programme will generate a large amount of data from distinct locations worldwide. To ensure comparability of results, data must be identified uniquely and standardisation of data analysis including the determination of derived quantities is necessary. A number of formulae are proposed for the normalisation and analysis of direct beam, global and diffuse irradiances and illuminances and sky luminance distributions. Graphical representation of results is discussed and a graphical approach, the P-G-D diagram, is put forward as a solution for irradiance and illuminance data presentation.

One of the tasks in sky modelling is the determination of the location and amount of cloud coverage in the sky. Analysis using digital camera systems is possible but requires an automated method of separating sky images into clear sky and cloud regions. Two segmentation approaches have been used in this research, one based purely upon the colour characteristics of sky regions, the other a neural network approach using a wider range of variables. A convolution technique was developed to reduce classification errors prior to defining cloud outlines using polylines. Sensitivity analysis shows that this can be carried out efficiently with little loss of accuracy.

This paper reports on the second stage of a study of gloom, part of a larger study which aims to quantify observers' impressions or general appearance of interiors. 'Gloom' refers to conditions, particularly in working environments such as offices, in which a room appears inadequately lit or underlit despite task area (working plane) illuminances which meet the recommendations of lighting standards and codes. An earlier paper reviewed the previous, largely anecdotal, work on the subject and established empirically that gloom is a commonly held experience. This was determined by making groups of observers appraise a room under three different lighting arrangements. The experiments reported here look at a larger range of conditions: twelve lighting conditions were examined in which the light in task and peripheral areas was varied systematically. By comparing the results from each condition it was possible to assess the importance of the adaptation luminance and the distribution of light in an interior in determining the subjects' impressions of a room.

This paper reports on the improvements in near visual acuity with increasing task illuminance for a group of partially-sighted people with various visual defects. The experimental method employed a technique which allows the easy transfer of experimental results to practical design. Comments are also made on the design of the visual environment for the partially sighted.

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