Martin OCZIPKA | Manuel SCHNEIDER
(Hochschule für Technik und Wirtschaft, Dresden, Germany)
Keywords: Photogrammetry, accuracy assessment, geometric resolution
Since the beginning of photography in the 1830s, the documentation of historical buildings and archaeological finding spots has been an important part of archaeology, architecture and many other sciences. Excavation destroy the finding spots irretrievable, buildings were destroyed or in a state of continuous decay or damaged or destroyed by warlike operations. Since that time, a wide range of technologic developments was archived. With high-resolution digital images, digital photogrammetry including the algorithms of computer vision as well as powerful computers equipped with high performance graphic cards, 3D modelling became an important tool for the documentation of all kinds of cultural heritage for many scientists.
In this example, terrestrial and airborne photos of a Bismarckturm in Dresden/Saxony were taken with a Canon 5D Mark3 and a Sony Alpha 6000 and processed to a high accuracy 3D model. The archived geometric resolution is 2.4mm; the radiometric resolution is 12bit and an accuracy of 1.2mm or half a pixel.
Digital terrestrial and aerial photography, Unmanned Aerial Systems and digital photogrammetry offer a bench of tools not only for experts, but also for non-professionals. Still, most of the products are not reliable. The leak of knowledge concerning cameras, interior and exterior orientation, algorithms and accuracy assessment cause main problems, while accuracy assessment make a 3D survey complete. Therefore, the resulting 3D models are often more or less similar models in an unknown accuracy of the actual object ignoring:
- camera accuracy and images quality,
- other photogrammetric principles,
- low cost technology is applied in a wrong way,
- reconstructed geometry might be wrong,
- image artefacts might be misinterpreted
- generally inaccurate or wrong positons on the earth’s surface
The benefit of these models is problematic.
This poster shows how to increase the quality and accuracy of models by applying generic rules of:
- Photogrammetric principles
- Proper use of cameras
- Self-calibration and camera parameters
- Flight and recording strategies
- Optimized processing
Relevance conference / Relevance session:
Many 3D-model in archaeology are of an unknown accuracy and have a more or less similarity to the real object.
The innovation is the sophisticated simplicity of photogrammetric processing.