[Back]

M. Adorjan:
"OpenSfM Ein kollaboratives Structure-from-Motion System";
Supervisor: M. Wimmer, M. Birsak; Institut für Computergraphik und Algorithmen, 2016; final examination: 2016-05-02.

Besides using high-cost laser scanning equipment to capture large point clouds for
topographical or architectural purposes, nowadays other, more affordable approaches
exist. Structure-from-motion (SfM) in combination with multi-view stereo (MVS) is
such a low-cost photogrammetric method used to generate large point datasets. It refers
to the process of estimating three-dimensional structures out of two-dimensional image
sequences. These sequences can even be captured with conventional consumer-grade
digital cameras.
In our work we aim to a establish a free and fully accessible structure-from-motion system,
based on the idea of collaborative projects like OpenStreetMap. Our client-server system,
called OpenSfM, consists of a web front-end which lets the user explore, upload and edit
SfM-datasets and a back-end that answers client requests and processes the uploaded
data and stores it in a database.
The front-end is a virtual tourism client which allows the exploration of georeferenced
point clouds together with their corresponding SfM-data like camera parameters and
photos. The information is rendered in the context of an interactive virtual globe. An
upload functionality makes it possible to integrate new SfM-datasets into the system
and improve or extend existing datasets by adding images that fill missing areas of the
affected point cloud. Furthermore, an edit mode allows the correction of georeferencing
or reconstruction errors.
On the other side the back-end evaluates the uploaded information and generates georeferenced
point datasets using a state-of-the-art SfM engine and the GPS data stored
in the uploaded images. The generated point clouds are preprocessed, such that they
can be used by the front-end´s point cloud renderer. After that, they are stored together
with the uploaded images and SfM parameters in the underlying database.
On the whole, our system allows the gathering of SfM-datasets that represent different
sights or landmarks, but also just locally famous buildings, placed all over the world.
Those datasets can be explored in an interactive way by every user who accesses the
virtual tourism client using a web browser.

http://publik.tuwien.ac.at/files/publik_253569.pdf