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Invited Session |
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| 10:30 to 12:30 - June, 20 (Friday) |
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Challenges in wide-area structure-from-motion |
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Marc Pollefeys (ETH-Zurich, Switzerland and UNC-Chapel Hill, USA) |
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In this talk, I
will present work on wide-area structure-from-motion
(SfM) such as city-wide 3D reconstructions from millions
of video frames. While in recent years a lot of
progress has been made in the area of SfM and multi-view
stereo reconstruction, wide-area 3D reconstructions and
mapping lead to interesting new research challenges. It
is for example important to use algorithms that are
efficient as typically millions of frames have to be
processed. In this context we will present algorithms
which exploit the tremendous computational power of
recent graphic processing units (GPU) to achieve
real-time performance. Another challenge consists of
avoiding unbounded accumulation of errors. For this it
is important to close loops when the camera path crosses
itself (e.g. at street intersections). We introduce
viewpoint-invariant-patches (VIP) to enable robust and
efficient matching over widely varying viewpoints (e.g.
orthogonal crossings). Our approach is illustrated with
3D reconstructions of Chapel Hill (where the last
edition of 3DPVT was held). |
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Marc Pollefeys |
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Photosynth and Beyond |
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Drew
Steedly (Microsoft Live Labs, USA) |
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Traditional photo browsing tools allow you browse through 2D pages of thumbnails. Photosynth lets you to browse photo collections in 3D space. This makes it easy to answer questions like "What is to the right of this photo?" and "Is there a more detailed photo of this part of the scene?". The Photosynth viewing experience relies on first automatically reconstructing the camera positions and a sparse point cloud. In this talk, I will discuss some recent enhancements to the viewing experience as well as a tool that allows users to interactively build textured 3D models from Photosynths. |
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Drew Steedly |
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Taking Google
Maps to Street Level |
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Jana Kosecka
(GMU and Google, USA) |
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I will describe Google's
Streetview feature from the conception of the idea to
initial capture experiments, challenges encoutered along
and present and future directions. I will talk about
what it takes to increase the quantity of coverage while
maintaining and improving the quality of one the few
application where the number of images can be measured
in miles. |
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Jana Kosecka |
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Fast, Automated, 3D, Airborne Modeling of Large Scale
Urban Environments |
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Avideh Zakhor (UC Berkeley, USA) |
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3D modeling of large scale environments is of
importance in many applications such as city planning, training and
simulations, architectural studies, gaming and entertainment, and
emergency services. In this talk, we describe an approach to fast,
automated, 3D modeling of large scale environments using airborne data
only. In contrast with ground based modeling which entails driving on
every street of a city, airborne data acquisition can be significantly
faster, and hence can scale to much larger areas. Our basic approach
is to construct the 3D geometry using airborne LiDAR data obtained by an
airplane, and to texture map this model using aerial imagery from a
helicopter equipped with inexpensive inertial measurement units (IMU).
At the core of our approach lies an automated algorithm for texture
mapping oblique aerial images onto a 3D model generated from airborne LiDAR data. Our proposed texture mapping algorithm consists of two
steps. In the first step, we combine vanishing points and global
positioning system aided inertial system readings to roughly estimate
the extrinsic parameters of a calibrated camera. In the second step, we
refine the coarse estimate of the first step by applying a series of
processing steps. Specifically, We extract 2D orthogonal corners (2DOCs)
corresponding to orthogonal 3D structural corners as features from both
images and the untextured 3D LiDAR model. The correspondence between an
image and the 3D model is then performed using Hough transform and
generalized M-estimator sample consensus. The resulting 2DOC matches are
used in Lowes algorithm to refine camera parameters obtained earlier.
Our system achieves 91% correct pose recovery rate for 90 images over
the downtown Berkeley area, and overall 61% accuracy rate for 358 images
over the residential, downtown and campus portions of the city of
Berkeley. |
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Avideh Zakhor |
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