11:35 AM - 11:55 AM
[U09-07] Research to create and publish DSM and DEM for the 1960s and early 1970s in urban areas of Japan
★Invited Papers
Keywords:digital surface models, digital elevation models, SfM-MVS analysis, land development, forest, 1960s
From the period of high economic growth (1956-1972) to the present, land development and deforestation progressed around urban areas, while forests were cleared and planted around mountainous areas, and agricultural lands were devastated. Collapse and deformation of embanked land during earthquakes and heavy rainfall is a problem in built-up areas created by land development. In addition, understanding forest and agricultural land transition is important for sustainable forest management and for measuring the quantity of biological resources. Time series analysis using highly accurate digital surface models (DSM) and digital elevation models (DEM) are effective in comprehensively understanding these man-made alteration sites and environmental and land use changes. However, currently there is no national DSM/DSM prior to the 1990s, which has been an obstacle to discussing current issues and dispositions by comparison with the past.
Therefore, from FY2023, the GSI is developing a method of creating past DSM/DEMs using past aerial photographs and SfM-MVS technology that is both accurate and efficient for surveying these transitions. Using the results of this research, 5 m-mesh DSM/DEM and orthoimages of the 1960s and early 1970s in 80% of the nation's urban area (approximately 90,000 km2) will be created and published by the end of FY2025. This presentation will report the results of a study of the optimal processing parameters (optimal values corresponding to conditions such as the age of the aerial photographs used, differences among cameras, etc.) when applying the SfM-MVS technique, and a study of the methods and procedures for placing ground reference points (GCPs). We will also report on cases in sample areas regarding the extraction of artificially altered land, analysis of topographical changes due to volcanic activity and landslides, and surface height changes due to deforestation and planting.
Therefore, from FY2023, the GSI is developing a method of creating past DSM/DEMs using past aerial photographs and SfM-MVS technology that is both accurate and efficient for surveying these transitions. Using the results of this research, 5 m-mesh DSM/DEM and orthoimages of the 1960s and early 1970s in 80% of the nation's urban area (approximately 90,000 km2) will be created and published by the end of FY2025. This presentation will report the results of a study of the optimal processing parameters (optimal values corresponding to conditions such as the age of the aerial photographs used, differences among cameras, etc.) when applying the SfM-MVS technique, and a study of the methods and procedures for placing ground reference points (GCPs). We will also report on cases in sample areas regarding the extraction of artificially altered land, analysis of topographical changes due to volcanic activity and landslides, and surface height changes due to deforestation and planting.