3 research outputs found
Hand-guided 3D surface acquisition by combining simple light sectioning with real-time algorithms
Precise 3D measurements of rigid surfaces are desired in many fields of
application like quality control or surgery. Often, views from all around the
object have to be acquired for a full 3D description of the object surface. We
present a sensor principle called "Flying Triangulation" which avoids an
elaborate "stop-and-go" procedure. It combines a low-cost classical
light-section sensor with an algorithmic pipeline. A hand-guided sensor
captures a continuous movie of 3D views while being moved around the object.
The views are automatically aligned and the acquired 3D model is displayed in
real time. In contrast to most existing sensors no bandwidth is wasted for
spatial or temporal encoding of the projected lines. Nor is an expensive color
camera necessary for 3D acquisition. The achievable measurement uncertainty and
lateral resolution of the generated 3D data is merely limited by physics. An
alternating projection of vertical and horizontal lines guarantees the
existence of corresponding points in successive 3D views. This enables a
precise registration without surface interpolation. For registration, a variant
of the iterative closest point algorithm - adapted to the specific nature of
our 3D views - is introduced. Furthermore, data reduction and smoothing without
losing lateral resolution as well as the acquisition and mapping of a color
texture is presented. The precision and applicability of the sensor is
demonstrated by simulation and measurement results.Comment: 19 pages, 22 figure
Single-shot 3D sensing with improved data density
We introduce a novel concept for motion robust optical 3D-sensing. The
concept is based on multi-line triangulation. The aim is to evaluate a large
number of projected lines (high data density) in a large measurement volume
with high precision. Implementing all those three attributes at the same time
allows for the "perfect" real-time 3D movie camera (our long term goal). The
key problem towards this goal is ambiguous line indexing: we will demonstrate
that the necessary information for unique line indexing can be acquired by two
synchronized cameras and a back projection scheme. The introduced concept
preserves high lateral resolution, since the lines are as narrow as the
sampling theorem allows, no spatial bandwidth is consumed by encoding of the
lines. In principle, the distance uncertainty is only limited by shot noise and
coherent noise. The concept can be also advantageously implemented with a
hand-guided sensor and real-time registration, for a complete and dense
3D-acquisition of complicated scenes
Uncalibrated Deflectometry with a Mobile Device on Extended Specular Surfaces
We introduce a system and methods for the three-dimensional measurement of
extended specular surfaces with high surface normal variations. Our system
consists only of a mobile hand held device and exploits screen and front camera
for Deflectometry-based surface measurements. We demonstrate high quality
measurements without the need for an offline calibration procedure. In
addition, we develop a multi-view technique to compensate for the small screen
of a mobile device so that large surfaces can be densely reconstructed in their
entirety. This work is a first step towards developing a self-calibrating
Deflectometry procedure capable of taking 3D surface measurements of specular
objects in the wild and accessible to users with little to no technical imaging
experience