摘要
在加利福尼亚州丘陵区和佛罗里达州滩涂区获得多时相航空摄影立体像对，构建数字表面模型。由于数字表面模型上记录着自然景观的三维表面坐标，我们可以测量沟壑侵蚀、河道窄化和深切以及海岸带滩涂地带盐沙地的移动，精度达到1m以内。本文使用的方法可为环境演变的定量化和进一步揭示环境演化规律提供精确参数。
We report a new application of digital photogrammetry for topographic changedetection. It is a by-product of our recent attempt toward the development of thefield of photo-ecometrics. We advocate the use of digital surface model (DSM) thatcontains the elevahon of all surface features such as buildings and trees rather thandigital elevahon model (DEM) that has been tradihonally used only for the terrain.We illustrate in this paper the usefulness of DSM and orthophotos generated withdigital photogrammetry in the monitoring of changes gully erosion, water channelincision and coastal salty sand zone displacements. Using 1; 12 000 aerial stereopairs acquired in the summers of 1970 and 1995 of ahilly savanna in Califodria and scanned at 25μm resolution, we derived DSMs andsubsequently orthophotos for each year. The spahal resolution of the scanned imageryis approximately 0.3m. We compared the same erosion zones and stream channels.We found tLhat the gully expansion in 1995 approximately doubled that in 1970. Onthe other hand, the stream channel in 1995 narrowed and was deeper than that in1970. The 70 m contour line in the study area advanced towards the upper streaxn forapproxiamtely 20 m during the 25 year period. Using 1;23 000 aerial stereopairs acqulred over coastal marshland area in Floridain 1951 and 1997, we produced a digital orthophoto for each year. The marshiand istransihonal between intide and above-tide land area. At the upper edge of themarshland, salty sandy zones can often be found due to adequate above-tide elevation,local evaporation intensity and sand type. Through measurement, we found that thelower boundaries of the salty sandy zones displaced toward the land for approximately3~ 5 m from 1951 to 1997. Since it was unlikely that the sand type had changedover the 46-year Period, the only possible explanahon is that either trhe annualaverage sea level or the evaporahon rate or both have undergone change in this area,leading to a conclusion that climate had changed over the 46-year period. There is no doubt that aerial photography and digital photography are gettingmore popular than before. Digital photogrammetry is a helpful tool for us to extractaccurate DSM data from stereopairs. As high resolution data from airborne andspace-borne remote sensing become more and more available, DSMs can be easilyobtained. Processing DSMs through shaPe analysis integrated with mulhspectral dataanalysis from traditional remote sensing will be a very powerful tool for changedetection. DSMs allow us to study changes not only about topography but also aboutcanopy closure and tree heights. The potential of DSMs opens many opportunities forimproving the accuracy of change detection.
出处
《第四纪研究》
CAS
CSCD
北大核心
2000年第3期247-251,T002,共6页
Quaternary Sciences
基金
国家杰出青年科学基金!B类4982551
国家自然科学基金!39899374
北京师范大学环境演变与自然灾害教育部重点实验室访问学者基金
美国森林
关键词
数字摄影测量
地形变化
数字表面模型
测量
digital photogrammetry, gully and water channel change, coastal marshland change
