Abstract
The ratio of vertical green coverage has generally been used in landscape evaluations. Until now, measurements of this ratio were calculated manually by researchers. However, it was difficult to obtain accurate data by this method due to the excessive time and effort required in the measurements and human error. This paper aims to clarify a new method of measuring the ratio of vertical green coverage using leaf colors. First, the author focused on leaf colors (in particular, chlorophyll) and specified the region of those colors in the CIE1976u’v’ chromaticity diagram in a sample survey of urban parks. Using the minimum value and maximum values from the CIE1976u’v’ chromaticity values of the leaf colors in photographs taken at the same points, the region for calculation was decided as an inside ellipse formed by the u’ axis (0.14 – 0.23) and v’ axis (0.49 – 0.56), excluding the area of gray in the field of the categorical color. The effectiveness of the approach using this region was validated in a 1-year field test. The results of a correlation analysis of 23 samples from these image data for the values calculated by this method and the values obtained manually showed a very high correlation coefficient (0.981). In conclusion, the use of this measurement method will enable easy, objective, correct, and useful calculation of the ratio of vertical green coverage, reflecting the differences of tree species and seasons.
