Building Rome in a Day

Entering the search term Rome on Flickr returns more than two million photographs. This collection represents an increasingly complete photographic record of the city, capturing every popular site, facade, interior, fountain, sculpture, painting, cafe, and so forth. It also offers us an unprecedented opportunity to richly capture, explore and study the three dimensional shape of the city.

In this project, we consider the problem of reconstructing entire cities from images harvested from the web. Our aim is to build a parallel distributed system that downloads all the images associated with a city, say Rome, from Flickr.com. After downloading, it matches these images to find common points and uses this information to compute the three dimensional structure of the city and the pose of the cameras that captured these images. All this to be done in a day.

This poses new challenges for every stage of the 3D reconstruction pipeline, from image matching to large scale optimization. The key contributions of our work is a new, parallel distributed matching system that can match massive collections of images very quickly and a new bundle adjust software that can solve extremely large non-linear least squares problems that are encountered in three dimensional reconstruction problems.

The project is a work in progress and over the next few months, we hope to have full scale results on data sets consisting of 1 million images and more. Shown below are some preliminary results of running our system on three city data sets downloaded from Flickr: Dubrovnik, Croatia; Rome and Venice, Italy. The static images were rendered from viewpoints chosen using the Canonical Views algorithm. Our current results are sparse point clouds, in collaboration with Yasutaka Furukawa we are also working on producing dense mesh models.

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Please bear in mind that this is a work in progress, but its future potential application for tourism and restoration (to name but two) is huge.

[Read the rest and see the videos including Dubrovnik and Venice at; http://grail.cs.washington.edu/rome/%5D

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