Naohiko OHNO
Improvement of method of extracting vegetation area in city where infrared rays aerophotograph image was used
Atsushi RIKIMARU, Kazuyoshi TAKAHASHI
Recently, environmental problems such as global warming have become aggravated. The city is greened in the global warming prevention. Greening the city can ease the heat island phenomenon of the city and control the temperature rise. It is necessary and indispensable to promote technological development and the spread of construction that occupies the majority of an urban area and greening the site to form the metropolitan environment that can environmental load little and continuation develop by promoting the urban revegetation in the future. Moreover, there is a nature environmental preservation base investigation being executed by the Ministry of the Environment. The Ministry of the Environment is executing the investigation based on regulations of the nature conservation law Article 4 from each 1973(1973) every five years so that the natural environmental preservation base investigation may understand the current state and the modification situation of domestic natural environment from a nationwide viewpoint, and maintain basic material to promote the measure of the preservation of the natural environment. However, it is hoped to have regularly to understand the vegetation area etc.
In the present study, it is a city part, and the vegetation area is extracted by using the each misjudgement with a small green space. The aerophotograph used the aerophotograph because there was an advantage with high spatial resolution, and it was suitable for obtaining information on the shape etc. of trees.
When the watching distinction and the site investigation are done to extract the vegetation area, time is spent very much. Then, the vegetation area has been extracted by using pixel value data of the aerophotograph for the labor saving.
In the method of extracting the vegetation area in a past city part, the index calculated according to watching decipherment and vegetation index NDVI is distinguished according to the threshold and the vegetation area has been extracted. However, non-vegetation area such as roofs is each misjudgement then as a vegetation area. Then, it is a purpose of the present study to improve the extraction method for non-vegetation area so as not to be each misjudgement as a vegetation area. And, the extraction of the vegetation area was tried by emphasizing the spectrum characteristic of the plant not used in NDVI that was earlier methods. The vegetation area has been extracted by proposing the index that non-vegetation area is not each misjudgement from the vegetation area, and using the index. Non-vegetation area's being each misjudgement as a vegetation area by combining proposed G?IR and B?IR index with NDVI has decreased. In addition, proposed city vegetation index UVI-1 vegetation area's being able to provide the threshold to one by using one, and being each misjudgement as a vegetation area have decreased.
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