The Filtering Technique Of High Precision DEM Based On Laser Scanning

Soil erosion is rather serious in China and has a wide range of distribution.In recent years, with the faster speed of national development and construction,people are paying more and more attention on soil erosion monitoring.As a result of surface erosion by the impact of a variety of forces,it is very difficult to monitor quantitatively,as surface erosion is affected by a variety of exogenetic force.At present,the relative lag in technology of soil erosion monitoring and the low degree of automation is difficult to satisfy the needs of rapid decision-making on the soil erosion prevention,supervision and law enforcement.In order to find fast,accurate and quantitative soil erosion monitoring method,introduction laser measurement technology was tried to introduce and the surface relative digit elevation(DEM) was obtained with using the laser scan,then the certain elevation's soil body volume on scanned sector was calculated.At last,the body accumulated rate,namely for soil erosion volume,was obtained by making use of the data came from two time interval scanning.According to soil bulk density corrosion quantity was obtained. If it is the loose soil formed from hand excavation,it would be deducted the soil of the nature settlement quantity which causes along with the stack time,and the residue was denominateed as corroded quantity.The core question affecting this kind of soil erosion monitor precision is the precision of the scan elevation.Obtaining high accuracy DEM is the key of monitoring technique.The laser scan precision was influenced by many kinds of factor,such as the laser head,equipment height, scanning angle,surface feature and terrain feature(for example illumination objects,such as water and quartz,absorb lasers,but vegetation mask causes data deficit),the scanning data are often randomly.In order to eliminate these influences and enhance the precision of the scanning elevation,based on this research in the overall analysis of microtopography characteristic,the surface object and the laser scan principle,the model of three dimensional data filter with the laser and its algorithm scan were proposed.Based on the calculated principle of the surface roughness,this model carries on the filter to the digital elevation.During the research process, compared the soil volume change as a result of the use of the filter model with the actual measurement,the precision is 98.2%.It showed that this method is feasible to monitor the soil erosion.