Since space to height index is effective on uniform illumination of working plane and it has been improved for two types of light sources, namely, point- and surface-circular-light sources in the literature, this study improves space to height index for line-light sources. Furthermore a comparison between new space to height indices and DIALux4.12 standard space to height indices, i.e. 0.25 and 1, is demonstrated for all of light sources.