Research On The Extraction Of DEM Based On High Resolution Remotely-sensed Data

In the construction of Planet Spatial Data Frame,digital elevation model(DEM) is one of the most indispensable and important geographic information.DEM has been playing a more and more significant role in all fields relative to topography.At the present time,the extraction of DEM involves three main methods:digital photogrammetry,laser and interferometer radar,among which digital photogrammetry is the uppermost means,collecting elevation through structuring stereo pair using computer stereoscopic vision.The accuracy of DEM has something to do with the base-height ratio.Because early remote sensing do not have the capacity of side looking,the base-height ratio is smaller and height information can not meet the needs. But recently situation has changed.The majority of high resolution satellites possess the side looking function and the base-height ratio is more close to airborne stereo pair,which make it possible to acquire DEM through satellites ways.Furthermore, satellite data has advantages such as steady source and low acquisition cost,which can shorten cycle time and improve efficiency.So far,on the DEM extraction practice, researches at home and abroad mostly center on Aster,SPOT,QuickBird and IKONOS data,few about Worldview-l.Due to its high resolution of 0.5m,study on DEM gain with it has a lot of signality.Process of DEM collection based on stereo pairs refers to relative orientation, absolute orientation,epipolar images generation and DEM editing.The past relative orientation utilizes sensor imaging parameters to position,but now many of the commercial satellites only provide parameters files including coefficients of Rational Function Model(RFM) instead of these ones.In this paper,we talk about definition, characteristics,resolving methods and process of RFM.Analysis is also made on DEM extraction based on stereo pairs with ENVI software.In addition,an experiment on DEM extraction is done using Ningbo Worldview-1 stereo pair.Compared to elevation points map of 1:10 scale,the root-mean-square error of DEM can reach to 11.11m.Research findings can help to impel Worldview-1 stereo pair application in DEM extraction,compensating for the problem of low efficiency and long cycle times and then improving accuracy.