Title : Interactive Manipulations in Reconstructed Urban Spaces

Project Lead : Duygu Ceylan From : EPFL (None)

Dates : from -- to --

Description :

Motivation and objectives :
Symmetry is a ubiquitous concept and repetitions are very common in many man-made objects because of its impact on economical and functional considerations and aesthetic concerns. For example, a chair is bilaterally symmetric to provide better balance, or a gear has rotational symmetry to continuously transfer rotational motion. Further, symmetry is regularly used as an organizing principle in urban planning and design, while use of repeating structures is reinforced to ease the construction process. Therefore, it is extremely important to explore such relations to enable a better understanding and processing of relevant data. Specifically, 3D reconstruction of urban scenes is one particular application that can benefit from the explicit knowledge of symmetry as each repeating element provides multiple observations of the same geometric piece. Reconstruction of urban spaces has a variety of applications such as: mapping and navigation, urban design, evacuation planning in emergency situations, and content creation for entertainment. Recently, the success of virtual navigation tools like Google Earth and Microsoft Visual Earth have attracted the attention of researchers towards this popular problem. Different strategies and multiple data sources (e.g., LIDAR scans, aerial images, GIS data, photographs) have been explored for fast and accurate reconstruction of urban facades and buildings. Image-based modeling methods have gained significant attention due to the advances in camera technology and the flexible and economic data acquisition possibilities they provide. Many challenges arising from lighting variations, insufficient textures, occluding objects, however, are still unsolved, especially in the reconstruction of clean, accurate, and detailed 3D models, which are often desirable for further interactive edits. Our goal is to introduce an image-based 3D reconstruction approach that addresses these challenges by using symmetry priors inherent in urban scenes. By exploring dominant repetitions and symmetries in the buildings we aim to provide high-quality 3D models of urban spaces which can be effectively used to create plausible virtual scenes and enable manipulations that can mimic real-world interactions. Our preliminary results in this direction has been recently accepted for a publication at EUROGRAPHICS 2012. Our long term objective is to explore future visualization systems that exploit both the 2D images and the 3D reconstructions together with an interactive editing facility to create an immersive experience for the users. Symmetry priors detected in the reconstruction phase can guide the editing process by providing semantic information of the geometric models. We would like to conduct usability surveys with the aim of improving workflow efficiency in several domains. Different domain possibilities include overlaying the 3D models with the existing 2D imagery, and urban plans in an immersive cave environment, or using hand-held devices on site to guide the navigation with real-time captured images.

Teams :
Computer Graphics and Geometry Laboratory at EPFL has been founded in 2010 and is headed by Prof. Mark Pauly. Currently, there are two post-graduate researchers and 5 PhD students conducting research mainly in computational symmetry, arhitectural geometry, and performance capture.

Dates :
starting date : 26 March, 2012
ending date : 12 April, 2012

Facilities descriptions :
http://visionair-browser.g-scop.grenoble-inp.fr/visionair/Browser/Catalogs/REACTOR.UK.html

Recordings & Results :
This project has developeda system which takes as input a set of images of a building faade and computes the transformations relating the images to each other and the 3D scene. This information is later used to perform image editing operations. The main challenge is to be able to compute reliable transformations between the input images.

Conclusions :
Results published in ACM Transactions on Graphics




Project Images :





Other project resources :

summary.pdf