Carbon dioxide which affects global warming a lot are increasing due to combustion caused from use of fossil fuels and change of land use according to urbanization. As a result, from a level responding to climate change around the world, an effort to reduce greenhouse gases is being made. At a national level, diverse trials are being realized to reduce Carbon dioxide as a main cause of greenhouse gases.
Trees conduct a positive role in reducing production of CO2 and providing comfort to citizens. But, as street trees planted in urban areas are controlled as a form of ledger based on documents, it is in a situation that exact numbers and heights of trees and so on are not controlled systematically. Previously, to acquire location information of trees, a way of aerial photogrammetry was used. But, owing to development of diverse sensor technologies, using not aerial photogrammetry but an aerial lidar survey, 3D information on objects are obtained.
The aerial lidar survey is a way to acquire information on objects as a type of points and has 3D coordinate values and reflection intensity. Using this information, to extract ground objects like trees, buildings, roads, etc, various works should be implemented using software. And, to extract correct objects, it is in a situation that handwork is necessary. Moreover, software for handling of aerial lidar data is mostly developed overseas, parts that do not fit to domestic geographical requirements happen.
Therefore, in this study, without lots of experiences on data processing in users’ aspect, a technique to extract trees automatically was developed. Based on this, a function of data processing was developed. The function to extract trees automatically in the aerial lidar was developed based on the model builder of ArcGIS. The developed technique was verified by comparing with and analyzing LIDAR Analyst as commercial software.
To verify the developed technique, by selecting some two areas of Yongin city in Gyeonggi province as study areas, data processing was conducted. The selected experimental areas are that dense areas of trees, apartment complexes, and residential zones coexist. They were named as experimental area A and B respectively. Using the technique proposed by this study, when comparing the result that trees in the experimental areas were extracted automatically with the result that trees were extracted automatically using the commercial software, the extraction rate of the technique proposed by this study was shown to be high by 40.52% in the experimental area A and high by 9.91% in the experimental area B.
Accordingly, the technique proposed by the study could extract trees relatively more effectively than the commercial software. By extracting locations, heights, and so on of trees automatically, these could be constructed in a database. Also, additionally using kinds and diameters at breast height of street trees which are controlled by local governments, absorption amounts of carbon dioxide and storage amounts of carbon were calculated and those were constructed into a database.
Through this study, the database of trees, especially street trees, which are controlled by local governments, could be constructed effectively. Moreover, a plan to reduce CO2 which should be controlled as a main object of global warming could be proposed.