The use of oblique and vertical images for 3D urban modelling

Hamruni, Ahmed Mohamed (2010) The use of oblique and vertical images for 3D urban modelling. PhD thesis, University of Nottingham.

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Abstract

Three-dimensional data are useful for various applications such as visualization for planning, simulation for training and environmental studies, presentations, decision making and many more.

The existing methods of texturing 3-D city models use conventional vertical imagery and libraries of generic textures which are sufficient for some applications of 3-D models like training simulation, gaming, and telecommunication planning. However, the needs for photo-realistic, modelling of the complete details, and geometrically accurate 3-D models are growing rapidly in several fields, especially in engineering and cultural heritage documentation. Photorealism and better details can be achieved through using terrestrial imagery but it is a very time-consuming process particularly in large modelling projects. It is possible to improve efficiency by image capture from a moving ground based vehicle but this requires an extra process in the work flow if the initial modelling has been undertaken by aerial photogrammetric processes.

Pictometry imagery has been used for visual inspection especially in life-saving situations due to the fact that the Pictometry aerial imagery contains oblique (angled) images which provide better view and greater detail. The more conventional method of collecting aerial images with for example the UltraCamD, can also provide excellent views of roof tops and some of the building facades when located away from the nadir on the images.

This research explored the geometry of the Pictometry images (vertical and oblique) and the possibility of using this imagery in 3-D modelling to produce photo-realistic and accurate models. In addition, merging terrestrial imagery with Pictometry imagery to get more ground level details has been investigated in this research.

All work has been carried out using the available software packages at the Institute of Engineering Surveying and Space Geodesy (IESSG) and using data provided by Blom Aerofilms Ltd.

The results of the aerial triangulation of different Pictometry blocks showed that high quality image measurements have been achieved for all the image blocks. The use of indirect georeferencing produced good quality coordination of ground points. The use of in-flight control has produced good results with additional parameters which mitigate any effects of systematic errors. Good quality AT results have been achieved using minimum ground control which reduces a lot of field work and hence time and money.

Extraction of 3D geometry for all buildings in the study area has been performed using both vertical Pictometry imagery and UltraCamD imagery. The polygons extracted from the UltraCamD images have been used as a bench mark (BM) to check the accuracy of polygons extracted from Pictometry.

Planimetric and height comparisons of the extracted features from Pictometry system with the BM results have been performed. The results showed that the Pictometry imagery produced good results especially in plan components taking into consideration the differences in the resolution, GSD, and the flying height between the two camera systems.

The results of automatically texturing the models have shown that using the vertical blocks (UltraCamD or Pictometry) produced very good roof textures but on the other hand produced less quality facades. The use of the Pictometry oblique block in texturing has produced very good facades but in some instances not such good quality roof textures.

The successful combining of vertical and oblique Pictometry images provided an excellent opportunity to produce an efficient method of high quality urban model texturing. The integration of terrestrial images of building facades (whose texture needs enhancement) with the combined aerial imagery block has been successfully and automatically performed. The results are much better than the results obtained by manual texturing which not only depends upon the experience and skill of the operator but is also time consuming and laborious

Item Type:Thesis (PhD)
Supervisors:Smith, M.J.
Bingley, R.M.
Faculties/Schools:UK Campuses > Faculty of Engineering > Department of Civil Engineering
ID Code:1551
Deposited By:Mr Ahmed Hamruni
Deposited On:18 May 2011 10:52
Last Modified:18 May 2011 10:52

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