Rouen Revisited

We are interested in widening these slices, extending and connecting the dots occupied by Monet's paintings in the multidimensional space of turn-of-the-century Rouen. In Rouen Revisited, we present an interactive kiosk in which users are invited to explore the façade of the Rouen Cathedral, as Monet might have painted it, from any angle, time of day, and degree of atmospheric haze. Users can contrast these re-rendered paintings with similar views synthesized from century-old archival photographs, as well as from recent photographs that reveal the scars of a century of weathering and war.

Rouen Revisited is our homage to the hundredth anniversary of Monet's cathedral paintings. Like Monet's series, our installation is a constellation of impressions, a document of moments and percepts played out over space and time. In our homage, we extend the scope of Monet's study to where he could not go, bringing forth his object of fascination from a hundred feet in the air and across a hundred years of history.

Many more ways of exploring and understanding the Gothic cathedral are afforded by moving between and around these modes. We can observe the many ways in which the cathedral has changed in the past century, for example, by moving between the re-renderings of the old photographs and those of the new photographs. We can come to an understanding of which geometric details Monet chose to focus on, by moving between views of his paintings and the historic photographs from the same time period. We can come to understand how the play of light at a given time of day may have inspired Monet to paint the colors and textures he did—by moving between a painting and the new photograph which shares the same time of day. And, when we scrub through the time-series of Monet paintings, we have a unique opportunity to access the entire set of Monet's Cathedral paintings, and gain an appreciation for the both the range of Monet's exploration as well as the constraints within which he chose to work. Finally, by changing the time of day and our point of view around the cathedral, we may derive a sense of place—a feeling for the Rouen Cathedral as a real physical artifact, and a sense of the passage of a day in Rouen.

Rouen Revisited is an artifact about artifacts about an artifact—an interactive and open-ended interpretation of paintings and photographs, which are themselves interpretations of an ancient Gothic artwork. Ultimately, the interpretation which Rouen Revisited affords is a dynamic one, forged in the mind of the user when she creates, using the multidimensional interface, her own Rouen Cathedral composition.

Users explore the surface of the Rouen Cathedral by touching one of three force-sensitive regions exposed within a brass plate mounted on the interface wedge. Each region affords the user with control of a different dimension of the façade:

• Touching the corners of the upper, triangular region of the brass plate allows users to select between renderings of Monet paintings, archival photographs from the 1890's, or new photographs from 1996. Dragging one's finger along this groove creates a blend between these modes.

• Moving one's finger left and right inside the central, upside-down-T-shaped region of the brass control plate allows users to change the time of day. Moving one's finger up and down the vertical groove of this control changes the level of fog. This control is disabled for the archival photographs, for which time-series and fog-series source stills were unavailable. Nevertheless, this control is active for the new photographs and Monet paintings, and permits users to draw comparisons between the actual appearance of the cathedral (given certain lighting conditions) and Monet's interpretation of the cathedral so lit.

• Dragging one's finger across the rectangular, bottom region of the brass plate allows users to change their point of view around the Rouen Cathedral.

Once the 3D model was built, the photographs and Monet paintings were registered with and projected onto the 3D model. Re-renderings of each of the projected paintings and photographs were then generated from hundreds of points of view; renderings of the cathedral in different atmospheric conditions and at arbitrary times of day were derived from our own time-lapse photographs of the cathedral and by interpolating between the textures of Monet's original paintings. The model recovery and image rendering was accomplished with custom graphics software on a Silicon Graphics Indigo2. The Rouen Revisited interface runs in a Macromedia Director projector on a 300-MHz Pentium PC, and allows unencumbered exploration of more than 12,000 synthesized renderings.

The execution of Rouen Revisited entailed more than half a dozen novel technical achievements. The most basic of these were the techniques of view-dependent texture-mapping, photogrammetric modeling, and model-based stereo that Paul Debevec developed in his Berkeley Ph.D. thesis. Other achievements, however, were more specific to the Rouen Revisited installation itself. A brief survey of the technological accomplishments in Rouen Revisited can be found here.

Further information about the modeling and rendering algorithms used in Rouen Revisited can be found in:

• Paul E. Debevec, Camillo J. Taylor, and Jitendra Malik. Modeling and Rendering Architecture from Photographs. In SIGGRAPH '96 Proceedings, August 1996

Paul Debevec received degrees in Math and Computer Engineering from the University of Michigan in 1992, and his Ph.D. in Computer Science at the University of California at Berkeley. For his doctoral thesis, Paul developed a method of modeling and rendering architectural scenes photorealistically from ordinary photographs by synthesizing techniques from computer vision with those of computer graphics. Paul is interested in continuing to capture, visualize, and interpret the world in new and creative ways through novel photographic techniques.

A photograph of the authors with the Rouen Revisited kiosk, August 1996.
A photograph of the authors in front of the Rouen Cathedral, January 1996.