Navigation: Drag time slider or use left/right arrow keys to flip through images. Click on an image to fly to it.
Mouse Look: Click and drag to rotate 3D view.
Zoom: Use up/down arrow keys to zoom in and out.
Selection: Click any building to view only images which see the building.
Orbit: Toggle orbit with 'o' key. When orbiting: toggle motion with spacebar, toggle active images with 'i'.
Other: Center view on image with 'c'. Toggle all buildings with 'a', no buildings with 'n'. Use number keys to jump along the timeline.
Link to Original Image (Opens in New Window): Hit 'L' key to link to original image -- make sure pop-up-blocking
is disabled.
Frequently Asked Questions
What am I looking at?
This is a 4D city model -- a 3D model of a city that changes over time.
How was it built?
Given hundreds of photographs of a city taken from multiple viewpoints and over centuries of time, we use a well-known computer vision technique called "structure from motion" to simultaneously
determine both the 3D structure of the buildings and the precise location of each image.
Is it completely automatic?
Not yet. The model shown here required that a human click on the top corners of a few buildings in all 200+ images in order to provide a set of corresponding 2D points to the "structure from motion"
algorithm. Here, dates were assumed known for each image and each building, but we have developed an automatic temporal inference method as
well.
Isn't this the same as Photosynth?
Microsoft's Photosynth is a fully automated system that utilizes the same underlying "structure from motion" concepts as used here. Our research focuses
on the unique problems that arise when time is introduced into large-scale 3D modeling of cities -- drastic time-induced changes in both 3D structure and appearance present problems for existing
techniques, such as those used by PhotoSynth. We know and love the folks behind Photosynth and Photo
Tourism, and are inspired by them every day.
I see a problem in the model.
This is a preview release of a work very much in progress, so there are some known issues.
Who funded this work?
The 4D Cities project is supported by an award from the National Science Foundation and a gift from Microsoft Research. We
are also very grateful to the Atlanta History Center for sharing with us their expertise and their priceless historical images of Atlanta.
Copyright 2008 Georgia Institute of Technology, Grant Schindler, Frank Dellaert. All Rights Reserved. All images copyright their respective owners. Some images courtesy of the Atlanta History Center. Built with Processing
