Digital Photogrammetry

Photogrammetry is a science based technology with more than a century of history and development. During this time, the techniques used to get information about objects represented in photos have changed dramatically from pure optic mechanical equipment to a fully digital workflow in our days. Parallel to this, the handling became easier, and so its possible also for non-photogrammetrists to use these methods today. This book is especially written for potential users which have no photogram metric education but would like to use the powerful capabilities from time to time or in smaller projects: Geographers, Geologists, Cartographers, Forest Engineers who would like to come into the fascinating field of photogrammetry via "learning by doing". For this reason, this book is not a textbook - for more and deeper the ory, there exists a lot ofliterature, and it is suggested to use some ofthis. A special recommendation should be given to the newest book from KONECNY (2002) for basic theory and the mathematical backgrounds or to the book from SCHENK (1999) for the particular situation in digital photogrammetry. For a quick reference especially to algorithms and technical terms see also the Photogrammetric Guide from ALBERTZ & KREILING (1989). This book includes a CD-ROM which contains all you need from software and data to learn about the various methods from the beginning (scanning of the pho tos) to final products like ortho images or mosaics.

1.1 Basic idea and main task of photogrammetry If you want to measure the size of an object, let’s say the length, width and height of a house, then normally you will carry this out directly at the object. Now imagine that the house didn’t exist anymore – it was destroyed, but some historic photos exist. Then, if you can determine the scale of the photos, it must be pos- ble to get the desired data. Of course you can use photos to get information about objects. This kind of - formation is different: So, for example, you may receive qualitative data (the house seems to be old, the walls are coloured light yellow) from photo interpre- tion, or quantitative data like mentioned before (the house has a base size of 8 by 6 meters) from photo measurement, or information in addition to your background knowledge (the house has elements of the “art nouveau” style, so may be c- th structed at the beginning of the 20 century), and so on.

Photogrammetry is the use of photography for surveying primarily and is used for the production of maps from aerial photographs. Along with remote sensing, it represents the primary means of generating data for Geographic Information Systems (GIS). As technology develops, it is becoming easier to gain access to it. The cost of digital photogrammetr

The first attempt to investigate this pervasive biological phenomenon from a variety of disciplines, from physics to mathematics to biology.

Photogrammetry is the use of photography for surveying primarily and is used for the production of maps from aerial photographs. Along with remote sensing, it represents the primary means of generating data for Geographic Information Systems (GIS). As technology develops, it is becoming easier to gain access to it. The cost of digital photogrammetric workstations are falling quickly and these new tools are therefore becoming accessible to more and more users. Digital Photogrammetry is particularly useful as a text for graduate students in geomantic and is also suitable for people with a good basic scientific knowledge who need to understand photogrammetry, and who wish to use the book as a reference.

Potential readers/users are students of Photogrammetry, Geodesy, Geography and other sciences, but also all who are interested in this topic. No prior knowledge is necessary, except the handling of standard PCs. Theory is presented true to the motto "as little as possible, but as much as necessary". The main part of the book contains several tutorials. In increasing complexity, accompanied by texts explaining further theory, the reader can proceed step by step through the particular working parts. Most of the standard work in Digital Photogrammetry is shown and trained for example scanning, image orientation, mono and stereo plotting, aerial triangulation measurement (manual and automatic), block adjustment, automatic creation of surface models via image matching, creation of ortho images and mosaics, and others. Not only standard situations are dealt with but also more complex ones, such as unknown camera data, extreme relief or areas with very low contrast. Examples of both aerial and close-range photogrammetry present the power of these type of measurement techniques. The software is not limited to the example data included but may be used for personal projects. Part of the book comprises a complete description of the software.

This textbook deals with the basics and methods of photogrammetry and laser scanning which are used to determine the form and location of objects, with measurements provided by sensors placed in air planes as well as on terrestrial platforms. Many examples and exercises with solutions are included. Photogrammetry, Laserscanning.