Kei HASEGAWA

Research on Extracting Failed Elevation Values of Snow Depth Data Measured by Aviation Laser System

Minjiao LU

Recently, a cutting edge measurement system has been drawing attention, which uses aircrafts to measure elevation data. This system utilizes infrared laser radiated from air crafts which reaches the surface of earth. Generally ,it is used to obtain DSM(Digital surface model) and DTM(Digital terrain model) .You can also get the elevation data of buildings and natural plants such as trees by subtracting DTM from DSM. In this way, you can filter out the extra data and gain the data you want.

This versatile system has been used for disaster prevention measures, for instance, you can predict disasters likely to happen such as droughts and inundation by knowing the structure of mountain slopes in advance. The other uses are a measurement of the sea depth , examination of environment and management of rivers.

If there is no obstacle such as high density plants and ponds or lakes whose depths frequently change, you can get almost precise data. However, It is impossible to gain it perfectly. Then , we have to consider a variety of causes which interrupt in the process of measurement .

My study is to find out the obstacles which interrupt the measurement. I mainly tackled this problem from the point of environmental factors such as natural plants, mountain slopes and the orientation. I used snow depth data gained by subtracting snow surface elevation data from DTM which is measured before snow fall. I examined both data and compared them in order to point out what is the main cause of failed value. I also attempted to separate failed elevation values and reliable values , so you can know what percent of them is available and the accuracy of the measurement. It will be very helpful if you can know these factors prior to the measurement.