10:15 AM - 10:30 AM
[HTT19-06] Red Relief Image Map using Hyper Resolution DEM, New Development of Topography recognition
Keywords:RED RELIEF IMAGE MAP, Terrain visualization, GIS
1. Introduction
Precise resolution DEM made by airborne LiDAR measurement is getting available. Elevation data of Well distributed Fundamental Geospatial Data (DEM) 5 m Mesh made by LiDAR of Geospatial Information Authority of Japan has been useful for understanding topography. Red Relief Image Map, hereinafter called RRIM (Chiba et al., 2004) is a visualization method which is improved slope map, but not include altitude information. RRIM with overlapping contour map make topography understanding more easily. The problem when overlapping RRIM with 5m DEM and GSI Map of level 15 is that RRIM looks significantly jaggy and is difficult to grasp topography. The resolution of GSI Map level 15 is around 50cm, but DEM 5m ten times lower. It does not solve the issue to make higher resolution DEM by image processing.
This study reports that RRIM with hyper resolution DEM applying interpolation and moving average is decreasing jaggy and increasing three-dimensional effect. Fundamental work-flow of this methodology and several case studies are described.
2. Methodology
Matrix data is split by n times both for X and Y direction. It is desirable that n is odd number. By linear interpolation is acceptable experientially. Loop process for moving average is applied until jaggy becoming inconspicuous. Too much loop process make the result smooth, but deviate from initial value. RRIM is made using hyper resolution DEM. When n equal 9, data volume is 81 times bigger. Since considering mesh number of positive openness and negative openness are becoming n times, computing time is getting longer.
3. Case studies
The comparison between RRIM using 5m resolution DEM and RRIM using Hyper resolution DEM on Asahi-ku, Yokohama City are shown (Fig. 1).Orthogonal roads in the developed residential area and slope feature in the surround hill area are clearly seen as well. The topography of terrace paddy field is better reproduced by Hyper resolution DEM, which was open to the public as WebGIS at Map Gallery of Esri User Conference 2020.2)
4. Conclusion
RRIM using Hyper resolution DEM visualize topography more smooth and easy to understand, and having high visibility when overlapping with GSI Map.The difficulty is that computing time is 100 times longer than previous method.
Reference
1) Tatsuro Chiba and Yusuke Suzuki (2004) Red relief image map,new topographical expression method, Proceedings of Applied Surveys, 15, 81-89.
2) Chiba T. and Ohashi M. (2020) Red Relief Image Map using Hyper Resolution DEM, ESRI map gallery 2020 User Conference, https://mapgallery.esri.com/map-detail/5efa4698f3b616cb34d9e11e
Precise resolution DEM made by airborne LiDAR measurement is getting available. Elevation data of Well distributed Fundamental Geospatial Data (DEM) 5 m Mesh made by LiDAR of Geospatial Information Authority of Japan has been useful for understanding topography. Red Relief Image Map, hereinafter called RRIM (Chiba et al., 2004) is a visualization method which is improved slope map, but not include altitude information. RRIM with overlapping contour map make topography understanding more easily. The problem when overlapping RRIM with 5m DEM and GSI Map of level 15 is that RRIM looks significantly jaggy and is difficult to grasp topography. The resolution of GSI Map level 15 is around 50cm, but DEM 5m ten times lower. It does not solve the issue to make higher resolution DEM by image processing.
This study reports that RRIM with hyper resolution DEM applying interpolation and moving average is decreasing jaggy and increasing three-dimensional effect. Fundamental work-flow of this methodology and several case studies are described.
2. Methodology
Matrix data is split by n times both for X and Y direction. It is desirable that n is odd number. By linear interpolation is acceptable experientially. Loop process for moving average is applied until jaggy becoming inconspicuous. Too much loop process make the result smooth, but deviate from initial value. RRIM is made using hyper resolution DEM. When n equal 9, data volume is 81 times bigger. Since considering mesh number of positive openness and negative openness are becoming n times, computing time is getting longer.
3. Case studies
The comparison between RRIM using 5m resolution DEM and RRIM using Hyper resolution DEM on Asahi-ku, Yokohama City are shown (Fig. 1).Orthogonal roads in the developed residential area and slope feature in the surround hill area are clearly seen as well. The topography of terrace paddy field is better reproduced by Hyper resolution DEM, which was open to the public as WebGIS at Map Gallery of Esri User Conference 2020.2)
4. Conclusion
RRIM using Hyper resolution DEM visualize topography more smooth and easy to understand, and having high visibility when overlapping with GSI Map.The difficulty is that computing time is 100 times longer than previous method.
Reference
1) Tatsuro Chiba and Yusuke Suzuki (2004) Red relief image map,new topographical expression method, Proceedings of Applied Surveys, 15, 81-89.
2) Chiba T. and Ohashi M. (2020) Red Relief Image Map using Hyper Resolution DEM, ESRI map gallery 2020 User Conference, https://mapgallery.esri.com/map-detail/5efa4698f3b616cb34d9e11e