Research Projects

Fast 3D modeling of large scale urban enviornments

Avideh Zakhor

Three dimensional modeling of objects, scenes, and urban environments, consisting of geometry and texture of visible surfaces, are useful in a variety of applications such as urban planning, training and simulation for disaster scenarios, virtual heritage conversation, and combating urban terrorism. In this project, we have developed an approach to fast, automated 3D model generation of urban environment so as to generate virtual, yet photorealistic walkthroughs drive throughs and fly throughs. To this end, we have developed two sets of modeling techniques; ground based, and airborne based. Our ground based modeling method uses a vehicle equipped with 2D laser scanners and a digital camera to acquire data to be processed offline, while driving under normal traffic conditions in public roads. Unlike previous approaches to urban modeling, this approach acquires data in a continuous “drive by scanning” way, rather than “stop and go” fashion. Associated with the ground based data set, is a set of algorithms we have developed in order to process the data and reconstruct the model in a fast, automated way; at the heart of these algorithms is Monte Carlo localization schemes that determine the position of our acquisition vehicle fairly accurately over long driving distances. Our airborne model is constructed from airborne laser data acquired with a flying airplane over the region of interest, and aerial images obtained from a helicopter at oblique angels. We have developed merging algorithms to combine the ground based and airborne models into one fused model which can then be used for virtual walkthroughs, drive throughs and fly throughs. We have obtained a 3D interactive model of downtown Berkeley [1][2] [3].

Figure 1
Figure 1: Rendered view of downtown Berkeley using fused 3D airborne/terrestrial model

C. Früh, S. Jain, and A. Zakhor, "Data Processing Algorithms for Generating Textured 3D Building Facade Meshes from Laser Scans and Camera Images", International Journal of Computer Vision, Vol. 61 No.2, Feb. 2005, pp. 159-184.[Adobe PDF]
C. Früh and A. Zakhor, "An Automated Method for Large-Scale, Ground-Based City Model Acquisition" in International Journal of Computer Vision, Vol. 60, No. 1, October 2004, pp. 5 - 24. [Adobe PDF]
C. Früh and A. Zakhor, "Constructing 3D City Models by Merging Ground-Based and Airborne Views" in Computer Graphics and Applications, November/December 2003, pp. 52 - 61. [Adobe PDF]