Study On Issues Related With True Digital Ortho Map Generation

With the development of Geomatics,True Digital Ortho Map(TDOM) has been a new application in the field of Photogrammetry.Geometric Rectification of True Digital Ortho Map(TDOM) based on Digital Surface Model(DSM) make the final image rectificated both in the terrain and the surface buildings.By keeping the vertical angle of the sight,TDOM solved many problems such as the difficulties of large-scale DOM(Digital Ortho Map) mosaicking in the city,the artificiality in the mosaicking area and other surface informations occluded by buildings.So TDOM which can apace form three-dimension scene in the city and the earth's surface,will have a great wide application in the city's spatial information field.It has been widely used in foreign countries.In this work,key steps of True Digital Ortho Map Generation are introduced. And based on the summery of applied methods and tracking of most recent researches on information of TDOM,practical workflows of image rectification and mosaicking are presented.We hope they can be applied in JX4 DPW(Digital Photogrammetry Workstation).In the part of image rectification,with the analysis of images' characters and the cause of the illumination phenomenon,a method to automatic searching for the occluded areas is utilized.It mainly based on Collinearity Equation in Photogrammetry and made the occlusion repaired from similar images.In the part of image mosaicking,based on color theory,the author mainly solved the problems of color balance and then present a method based on Wallis filter which pay attention on both overall and local information of image.In the end,the author summarized problems that may occur in True Digital Ortho Map generation and presented relevant control measures.