Aerial Photogrammetry Prof Mandar Mahajan SurveyingII RSCOE 1

Aerial Photogrammetry Prof. Mandar Mahajan Surveying-II RSCOE 1

Lecture outline • Photogrammetry ? • Principle of photogrammetry • Uses • Aerial camera • Aerial photograph. • Scale of vertical and tilted photograph • Ground coordinates Prof. Mandar Mahajan • Procedure of aerial survey. • Photomaps and mosaics • Stereoscopes • Parallax Bar Surveying-II RSCOE 2

What is photogrammetry? Art and Science of obtaining information about physical objects and the environment by photographic and electromagnetic images through processes of recording, measuring, and interpreting photographic images Science: Measuring From Art: Photo Interpretation ( examining Photograph (Geometric Char) Photograph Objects) Prof. Mandar Mahajan Surveying-II RSCOE 3

Principle of photogrammetric survey • Principle of photogrammetric survey is very similar to that of the plane table survey. • The principal point of each photograph is used as a fixed station and rays are drawn to get points of intersections very similar to those used in plane table. • suitable for topographical or engineering surveys and also for those projects demanding higher accuracy Prof. Mandar Mahajan Surveying-II RSCOE 4

Broadly photogrammetry requires • Planning and taking photographs • Processing the photographs • Measuring the photographs and reducing the measurments to produce the results Prof. Mandar Mahajan Surveying-II RSCOE 5

Photogrammetry for Engineering Photogrammetry is the process of measuring images on a photograph • measuring images - accurate measurements - without any physical contact • photograph - planimetric/Topographic maps - preparation of composite picture on the ground • Classification of photogrammetry - Terrestrial Photogrammetry : fixed position - Aerial Photogrammetry : aircraft flying over the area (Aerial survey) Prof. Mandar Mahajan Surveying-II RSCOE 6

Principal application of photogrammetry ? § Topographic application : To determine the spatial position of the natural and man- made features situated on the earth's surface § Non-topographic applications : measuring tool in 1. Architecture 2. industrial design 3. deformation studies of structures 4. accident investigation 5. medicine etc Prof. Mandar Mahajan Surveying-II RSCOE 7

Applications of Photogrammetry Topographic mapping Prof. Mandar Mahajan Surveying-II RSCOE 8

Applications of Photogrammetry • Creation of value added product - Orthoimages - Digital Elevation Model (DEM) - Virtual Landcapes Prof. Mandar Mahajan Surveying-II RSCOE 9

What can photogrammetry do? ØAccurate 2 D and 3 D measurements ØInformation required: images and sensor (camera) parameters Aerial photos : can not be used ØDesert or plains areas, sandy beaches, snow -the photograph as uniform shades with little texture. ØDeep canyons or high buildings that conceal ground surface ØAreas covered by dense forest. Prof. Mandar Mahajan Surveying-II RSCOE 10

• Mapping, Interpretation, Map substitute • Mapping from Aerial photos is the best mapping procedure yet developed for most large projects. • Maps scale from 1: 1, 000 , 1: 120 with C. I. from as small as 1 foot. • Reconstruct a scaled 3 -dimensional optical model of the lands surface using Stereoplotter Prof. Mandar Mahajan Surveying-II RSCOE 11