E1AR0002@SMUVM1.BITNET (02/27/86)
:aim 698
:title {Robot Programming}
:author Tomas Lozano-Perez
:asort Lozano-Perez, T.
:date December 1982
:cost $2.75
:pages 57
:ADnum (AD-A127233)
:keywords robotics, robot programming
:abstract
The industrial robot's principal advantage over traditional automation
is programmability. Robots can perform arbitrary sequences of
pre-stored motions or of motions computed as functions of sensory
input. This paper reviews requirements for and developments in robot
programming systems. The key requirements for robot programming
systems examined in the paper are in the areas of sensing, world
modeling, motion specification, flow of control, and programming
support. Existing and proposed robot programming systems fall into
three broad categories: guiding systems in which the user leads a
robot through the motions to be performed, robot-level programming
systems in which the user writes a computer program specifying motion
and sensing, and task-level programming systems in which the user
specifies operations by their desired effect objects. A
representative sample of systems in each of these categories is
surveyed in the paper.
:end
:aim 699
:title {The Measurement of Visual Motion}
:author Ellen C. Hildreth and Shimon Ullman
:asort Hildreth, E.; Ullman, S.
:date December 1982
:cost $2.25
:pages 26
:ADnum (AD-A128398)
:keywords motion measurement, velocity field, optical flow,
zero crossings, motion perception
:abstract
The analysis of visual motion divides naturally into two stages: the
first is the measurement of motion, for example, the assignment of
direction and magnitude of velocity to elements in the image, on the
basis of the changing intensity pattern; the second is the use of
motion measurements, for example, to separate the scene into distinct
objects, and infer their three-dimensional structure. In this paper,
we present a computational study of the measurement of motion.
Similar to other visual processes, the motion of elements is not
determined uniquely by information in the changing image; additional
constraint is required to compute a unique velocity field. Given this
global ambiguity of motion, local measurements from the changing
image, such as those provided by directionally-selective simple cells
in primate visual cortex, cannot possible specify a unique local
velocity vector, and in fact, specify only one component of velocity.
Computation of the full two-dimensional velocity field requires the
integration of local motion measurements, either over an area, or
along contours in the image. We will examine possible algorithms for
computing motion, based on a range of additional constraints.
Finally, we will present implications for the biological computation
of motion.
:end
:aim 700
:title {Dynamic Scaling of Manipulator Trajectories}
:author John M. Hollerbach
:asort Hollerbach, J.M.
:date January 1983
:cost $1.50
:pages 13
:ADnum (AD-A127074)
:keywords manipulators, robotics, trajectory planning, manipulator
dynamics
:abstract
A fundamental time-scaling property of manipulator dynamics has been
identified that allows modification of movement speed without complete
dynamics recalculation. By exploiting this property, it can be
determined whether a planned trajectory is dynamically realizable
given actuator torque limits, and if not, how to modify the trajectory
to bring it within dynamic and actuating constraints.
:end
:aim 701
:title {Computational Introspection}
:author John Batali
:asort Batali, J.
:date February 1983
:cost $3.00
:pages 68
:ADnum (AD-A127132)
:keywords problem solving, reflection, action, philosophy of mind,
introspection, LISP, representation
:abstract
Introspection is the process of thinking about one's own thoughts and
feelings. In this paper, I discuss recent attempts to make
computational systems that exhibit introspective behavior: [Smith,
1982], [Weyhrauch, 1978], and [Doyle, 1980]. Each presents a system
capable of manipulating representations of its own program and current
context. I argue that introspective ability is crucial for intelligent
systems -- without it an agent cannot represent certain problems that it
must be able to solve. A theory of intelligent action would describe
how and why certain actions intelligently achieve an agent's goals.
The agent would both embody and represent this theory: it would be
implemented as the program for the agent; and the importance of
introspection suggests that the agent represent its theory of action
to itself.
:end
:aim 702
:title {Representations for Reasoning About Change}
:author Reid G. Simmons and Randall Davis
:asort Simmons, R.G.; Davis, R.
:date April 1983
:cost $2.75
:pages 54
:reference See SIGART Proc., April 1983, Workshop on Motion, Toronto, Canada,
:ADnum (AD-A131649)
:keywords processes, action, knowledge representation, expert systems,
qualitative reasoning
:abstract
This paper explores representations used to reason about objects which
change over time and the processes which cause changes. Specifically,
we are interested in solving a problem known as geologic
interpretation. To help solve this problem, we have developed a
simulation technique, which we call {\it imagining}. Imagining takes
a sequence of events and simulates them by drawing diagrams
In order to do this imagining, we have developed two representations
of objects, one involving {\it histories} and the other involving {\it
diagrams} and two corresponding representations of physical
processes, each suited to reasoning about one of the object
representations. These representations facilitate both spatial and
temporal reasoning.
:end
:aim 705
:title {Tactile Recognition and Localization Using Object Models: The Case of Po
lyhedra on a Plane}
:author Peter C. Gaston and Tomas Lozano-Perez
:asort Gaston, P.; Lozano-Perez, T.
:date March 1983
:cost $2.25
:pages 22
:ADnum (AD-A127228)
:keywords tactile sensing, robotics
:abstract
This paper discusses how data from multiple tactile sensors may be
used to identify and locate one object, from among a set of known
objects. We use only local information from sensors:(1)the position of
contact points, and (2)ranges of surface normals at the contact
points. The recognition and localization process is structured as the
development and pruning of a tree of consistent hypotheses about
pairings between contact points and object surfaces. In this paper,
we deal with polyhedral objects constrained to lie on a known plane,
i.e., having three degrees of positioning freedom relative to the
sensors.
:end
:aim 706
:title {Computational Studies in the Interpretation of Structure and Motion: Sum
mary and Extension}
:author Shimon Ullman
:asort Ullman, S.
:date March 1983
:cost $2.25
:pages 26
:ADnum (AD-A131598)
:keywords motion perception, visual motion, optical flow,
structure from motion
:abstract
Computational studies of the interpretation of structure from motion
examine the conditions under which three-dimensional structure can be
recovered from motion in the image. The first part of this paper
summarizes the main results obtained to date in these studies. The
second part examines two issues: the robustness of the 3-D
interpretation of perspective velocity fields, and the 3-D information
contained in orthographic velocity fields. The two are related
because, under local analysis, limitations on the interpretation of
orthographic velocity fields also apply to perspective projection.
The following results are established: (1) When the interpretation is
applied locally, the 3-D interpretation of the perspective velocity
field is unstable. (2) The orthographic velocity field determines the
structure of the inducing object exactly up to a depth-scaling. (3) For
planar objects, the orthographic velocity field always admits two
distinct solutions up to depth-scaling. (4) The 3-D Structure is
determined uniquely by a "view and a half" of the orthographic velocity field.
:end
:aim 708
:title Solving Uninterpreted Equations with Context Free Expression Grammars
:author David McAllester
:asort McAllester, D.A.
:date May 1983
:cost $2.25
:pages 31
:ADnum AD-A133613
:keywords theorem proving, congruence closure, simplification,
automated deduction, context free grammar
:abstract
It is shown here that the equivalence class of an expression under the
congruence closure of any finite set of equations between ground terms
is a context free expression language. An expression is either a
symbol or an n-tuple of expressions; the difference between
expressions and strings is that expressions have inherent phrase
structure. The Downey, Sethi, and Tarjan algorithm for computing
congruence closures can be used to convert a finite set of equations
$\Sigma$ to a context free expression grammar $G$ such that for any
expression $u$ the equivalence class of $u$ under $\Sigma$ is precisely the
language generated by an expression form $\Gamma(u)$ under the
grammar $G$. The fact that context free {\it expression} languages are
closed under intersection is used to derive an algorithm for computing
a grammar for the equivalence class of a given expression under any
finite disjunction of finite sets of equations between ground
expressions. This algorithm can also be used to derive a grammar
representing the equivalence class of conditional expressions of the
form {\bf if} P {\bf then} $u$ {\bf else} $v$. The description of an
equivalence class by a context free expression grammar can also be
used to simplify expressions under "well behaved" simplicity orders.
Specifically if $G$ is a context free expression grammar which generates
an equivalence class of expressions then for any well behaved
simplicity order there is a subset $G^\prime$ of the productions of
$G$ such that the expressions generated by $G$ are exactly those
expressions of the equivalence class which are simplicity bounds and
whose subterms are also simplicity bounds. Furthermore $G^\prime$
can be computed from $G$ in order $n\log(n)$ comparisons between
expressions where $n$ is the size of $G$.
:end
:aim 710
:title {Symmetric Set Theory: A General Theory of Isomorphism, Abstraction, and
Representation}
:author David Allen McAllester
:asort McAllester, D.A.
:date August 1983
:cost $2.25
:pages 30
:ADnum AD-A133630
:abstract
It is possible to represent a finite set of points (atoms) by a finite
sequence of points. However a finite set of points has no
distinguished member and therefore it is impossible to define a
function which takes a finite set of points and returns a "first"
point in that set. Thus it is impossible to represent a finite
sequence of points by a finite set of points. The theory of symmetric
sets provides a framework in which this observation about sets and
sequences can be proven. The theory of symmetric sets is similar to
classical (Zermello-Fraenkel) set theory with the exception that the
universe of symmetric sets includes points (ur-elements). Points
provide a basis for general notions of isomorphism and symmetry. The
general notions of isomorphism and symmetry in turn provide a basis
for natural, simple, and universal definitions of abstractness,
essential properties and functions, canonicality, and representations.
It is expected that these notions will play an important role in the
theory of data structures and in the construction of general
techniques for reasoning about data structures.
:end
:aim 711
:title {An Extremum Principle for Shape from Contour}
:author Michael Brady and Alan Yuille
:asort Brady, M.; Yuille, A.L.
:date June 1983
:cost $2.25
:pages 35
:ADnum (AD-A131321)
:keywords shape from contour, image understanding, 3-D vision
:abstract
An extremum principle is developed that determines three-dimensional
surface orientation from a two-dimensional contour. The principle
maximizes the ratio of the area to the square of the perimeter, a
measure of the compactness or symmetry of the three-dimensional
surface. The principle interprets regular figures correctly and it
interprets skew symmetries as oriented real symmetries. The maximum
likelihood method approximates the principle on irregular figures, but
we show that it consistently overestimates the slant of an ellipse.
:end
:aim 712
:title {Information Processing in Dendritic Spines}
:author C. Koch and T. Poggio
:asort Koch, C.; Poggio, T.
:date March 1983
:cost $1.50
:pages 11
:keywords spines, memory, connectivity, neural hardware
:abstract
Dendritic spines are small twigs on the dendrites of very large class
of neurons in the central nervous system. There are between 10/3 and
10/5 spines per neuron, each one including at least one synapse, i.e
a connection with other neurons. Thus, spines are usually associated
with an important feature of neurons - their high degree of
connectivity - one of the most obvious differences between present
computers and brains. We have analysed the electrical properties of a
cortical (spiny) pyramidal cell on the basis of passive cable theory,
from measurements made on histological material, using the solution of
the cable equation for an arbitrary branched dendritic tree. As
postulated by Rall, we found that the somatic potential induced by a
firing synapse on a spine is a very sensitive function of the
dimension of the spine. This observation leads to several hypotheses
concerning the electrical functions of spines, especially with respect
to their role in memory.
:end
:aim 713
:title {A Theoretical Analysis of Electrical Properties of Spines}
:author C. Koch and T. Poggio
:asort Koch, C.; Poggio, T.
:date April 1983
:cost $2.25
:pages 27
:keywords dendritic spines, nerve cells, information processing, memory
:abstract
The electrical properties of a cortical (spiny) pyramidal cell were
analyzed on the basis of passive cable theory from measurements made
on histological material (Koch, Poggio and Torre 1982). The basis of
this analysis is the solution of the cable equation for an arbitrary
branched dendritic tree. We determined the potential at the soma as a
function of the spine neck dimensions. From our investigation four
major points emerge: 1. Spines may effectively compress the effect of
each single excitatory synapse on the soma, mapping a wide range of
inputs onto a limited range of outputs (nonlinear saturation). This
is also true for very fast transient inputs, in sharp contrast with
the case of a synapse on a dendrite. 2. The somatic depolarization
due to an excitatory synapse on a spine is a very sensitive function
of the spine neck length and diameter. Thus the spine can effectively
control the attenuation of its input via the dimensions of the neck,
thereby setting the shape of the resulting saturation curve. This
might be the basic mechanism underlying ultra-short memory, long-term
potentiation in the hippocampus or learning in the cerebellum. 3.
Spines with shunting inhibitory synapses on them are ineffective in
reducing the somatic depolarization due to excitatory inputs on the
dendritic shaft or on other spines. Thus isolated inhibitory synapses
on a spine are not expected to occur. 4. The conjunction of an
excitatory synapse with a shunting inhibitory synapse on the same
spine may result in a time-discrimination circuit with a temporal
resolution of around 100.
:end
:aim 714
:title {Determining Attitude of Object From Needle Map Using Extended Gaussian I
mage}
:author Katsushi Ikeuchi
:asort Ikeuchi, K.
:date April 1983
:cost $2.25
:pages 26
:ADnum (AD-A131617)
:keywords computer vision, object attitude, bin picking, Gauss map,
least inertia axis, tessellated dome, look-up table
:abstract
An extended Gaussian image (EGI) is constructed by mapping the surface
normals of an object onto the Gaussian sphere. The attitude of an
object is greatly constrained by the global distribution of EGI mass
over the visible Gaussian hemisphere. Constraints on viewer direction
are derived from the position of the EGI mass center, and from the
direction of the EGI inertia axis. The algorithm embodying these
constraints and the EGI mass distribution are implemented using a
lookup table. A function for matching an observed EGI with the
prototypical EGIS is also proposed. The algorithm determines the
attitude of an object successfully both from a synthesized needle map
and a real needle map.
:end
:aim 716
:title {Understanding Text through Summarization and Analogy}
:author Graziella Tonfoni and Richard J. Doyle
:asort Tonfoni, G.; Doyle, R.J.
:date April 1983
:cost $2.25
:pages 37
:keywords plot units, analogy, summary, text-production
:abstract
Understanding a text exactly in the way that the Text Producer meant
the text to be understood is highly unlikely unless the text
interpretation process is constrained. Specific understanding-directing
criteria are given in the form of a Premise which is a configuration
of plot-units. After performing a Premise-directed text
summarization, the Text Receiver will have understood the text as the
Text Producer intended and will then be able to replace missing
relations within the exercises and produce new texts by applying
analogy.
:end
:aim 717
:title {Wrist-Partitioned Inverse Kinematic Acceleration and Manipulator Dynamic
s}
:author John M. Hollerbach and Gideon Sahar
:asort Hollerbach, J.M.; Sahar, G.
:date April 1983
:cost $2.25
:pages 25
:keywords robotics, kinematics, dynamics, control
:abstract
An efficient algorithm is presented for the calculation of the inverse
kinematic accelerations for a 6 degree-of-freedom manipulator with a
spherical wrist. The inverse kinematic calculation is shown to work
synergistically with the inverse dynamic calculation, producing
kinematic parameters needed in the recursive Newton-Euler dynamics
formulation. Additional savings in the dynamics computation are noted
for a class of kinematically well-structured manipulators such as
spherical-wrist arms and for manipulators with simply-structured
inertial parameters.
:end
:aim 718
:author A. Yuille
:asort Yuille, A.L.
:title Zero-Crossings on Lines of Curvature
:date December 1984
:cost $2.25
:pages 23
:Adnum AD-A150171
:keywords photometric invariants, zero crossings, lines of curvature,
parabolic lines
:abstract
We investigate the relations between the structure of the image and
events in the geometry of the underlying surface. We introduce some
elementary differential geometry and use it to define a coordinate
system on the object based on the lines of curvature. Using this
coordinate system we can prove results connecting the extrema, ridges
and zero-crossings in the image to geometrical features of the object.
We show that extrema of the image typically correspond to points on the
surface with zero Gaussian curvature and that parabolic lines often
give rise to ridges, or valleys, in the image intensity. We show that
directional zero-crossings of the image along the lines of curvature
generally correspond to extrema of curvature along such lines.
:aim 719
:title {Semantic Support for Work in Organizations}
:author Gerald Barber, Peter de Jong, and Carl Hewitt
:asort Barber, G.; de Jong, P.; Hewitt, C.
:date April 1983
:cost $1.50
:pages 14
:ADnum (AD-A130457)
:keywords problem solving, office systems, open systems, actors,
application systems, message passing semantics, OMEGA, sprites
:abstract
Present day computer systems cannot implement much of the work carried
out in organizations such as: planning, decision making, analysis, and
dealing with unanticipated situations. Such organizational activities
have traditionally been considered too unstructured to be suitable for
automation by computer. We are working on the development of a
computer system which is capable of the following: describing the
semantics of applications as well as the structure of the organization
carrying out the work, aiding workers in carrying out the applications
using these descriptions, and acquiring these capabilities in the
course of the daily work through a process which is analogous to
apprenticeship.
:end
:aim 721
:title {Maximizing Rigidity: The Incremental Recovery of 3-D Structure From Rigi
d and Rubbery Motion}
:author Shimon Ullman
:asort Ullman, S.
:date June 1983
:keywords motion perception, structure from motion, rigidity,
rubbery motion, kinetic depth effect
:cost $2.25
:pages 30
:abstract
The human visual system can extract 3-D shape information of
unfamiliar moving objects from their projected transformations.
Computational studies of this capacity have established that 3-D
shape can be extracted correctly from a brief presentation, provided
that the moving objects are rigid. The human visual system requires a
longer temporal extension, but it can cope, however, with considerable
deviations from rigidity. It is shown how the 3-D structure of rigid
and non-rigid objects can be recovered by maintaining an internal model
of the viewed object and modifying it at each instant by the minimal
non-rigid change that is sufficient to account for the observed
transformation. The results of applying this incremental rigidity
scheme to rigid and non-rigid objects in motion are described and
compared with human perceptions.
:end
:aim 722
:title {Scaling Theorems for Zero-Crossings}
:author A.L. Yuille and T. Poggio
:asort Yuille, A.L.; Poggio, T.
:date June 1983
:cost $2.25
:pages 25
:ADnum (AD-A131599)
:abstract
We characterize some properties of the zero-crossings of the laplacian
of signals - in particular images - filtered with linear filters, as a
function of the scale of the filter (following recent work by A.
Witkin, 1983). We prove that in any dimension the only filter that
does not create zero-crossings as the scale increases is the gaussian.
This result can be generalized to apply to level-crossings of any
linear differential operator: it applies in particular to ridges and
ravines in the image intensity. In the case of the second derivative
along the gradient we prove that there is no filter that avoids
creation of zero-crossings.
:end
:aim 723
:title {Visual Routines}
:author Shimon Ullman
:asort Ullman, S.
:date June 1983
:cost $2.75
:pages 66
:ADnum AD-A133634
:keywords vision, visual routines, pattern recognition, space
perception, spatial information processing
:abstract
This paper examines the processing of visual information beyond the
creation of the early representations. A fundamental requirement at
this level is the capacity to establish visually abstract shape
properties and spatial relations. This capacity plays a major role in
object recognition, visually guided manipulation, and more abstract
visual thinking. For the human visual system, the perception of
spatial properties and relations that are complex from a computational
standpoint, nevertheless often appears immediate and effortless. This
apparent immediateness and ease of perceiving spatial relations is,
however deceiving. It conceals in fact a complex array of processes
highly specialized for the task. The proficiency of the human system
in analyzing spatial information far surpasses the capacities of
current artificial systems. The study of the computations that
underlie this competence may therefore lead to the development of new
more efficient processors for the spatial analysis of visual
information. It is suggested that the perception of spatial relations
is achieved by the application to the base representations of visual
routines that are composed of sequences of elemental operations.
Routines for different properties and relations share elemental
operations. Using a fixed set of basic operations, the visual system
can assemble different routines to extract an unbounded variety of
shape properties and spatial relations. At a more detailed level, a
number of pausible basic operations are suggested, based primarily on
their potential usefulness, and supported in part by empirical
evidence. The operations discussed include shifting of the processing
focus, indexing to an odd-man-out location, bounded activation,
boundary tracing, and marking. The problem of assembling such
elemental operations into meaningful visual routines is discussed briefly.
:end
:aim 724
:title {The Smoothest Velocity Field and Token Matching}
:author A.L. Yuille
:asort Yuille, A.L.
:date August 1983
:cost $1.50
:pages 10
:ADnum AD-A133633
:keywords motion measurement, velocity field, optical flow,
zero crossings, motion perception
:abstract
This paper presents some mathematical results concerning the
measurement of motion of contours. A fundamental problem of motion
measurement in general is that the velocity field is not determined
uniquely from the changing intensity patterns. Recently Hildreth \&
Ullman have studied a solution to this problem based on an Extremum
Principle [Hildreth (1983), Ullman \& Hildreth (1983)]. That is, they
formulate the measurement of motion as the computation of the
smoothest velocity field consistent with the changing contour. We
analyze this Extremum Principle and prove that it is closely related
to a matching scheme for motion measurement which matches points on
the moving contour that have similar tangent vectors. We then derive
necessary and sufficient conditions for the principle to yield the
correct velocity field. These results have possible implications for
the design of computer vision systems, and for the study of human vision.
:end
:aim 725
:title {Planning Collision Free Motions for Pick and Place Operations}
:author Rodney A. Brooks
:asort Brooks, R.A.
:date May 1983
:cost $2.75
:pages 49
:ADnum (AD-A130448)
:keywords find-path, collision free paths, pick and place, collision avoidance
:abstract
An efficient algorithm which finds collision free paths for a
manipulator with 5 or 6 revolute joints is described. It solves the
problem for four degree of freedom pick and place operations Examples
are given of paths found by the algorithm in tightly cluttered
workspaces. The algorithm first describes free space in two ways: as
freeways for the hand and payload ensemble and as freeways for the
upperarm. Freeways match volumes swept out by manipulator motions and
can be "inverted" to find a class of topologically equivalent path
segments. The two freeway spaces are searched concurrently under
vprojection of constraints determined by motion of the forearm.
:end
:aim 726
:title {Picking up an Object from a Pile of Objects}
:author Katsushi Ikeuchi, Berthold K.P. Horn, Shigemi Nagata, Tom
Callahan, and Oded Feingold
:asort Ikeuchi, K.; Horn, B.K.P.; Nagata, S.; Callahan, T.; Feingold, O.
:date May 1983
:cost $2.25
:pages 27
:ADnum AD-A133631
:keywords photometric stereo, Puma arm, hand-eye system, extended
Gaussian image, bin picking, visual guidance
:abstract
This paper describes a hand-eye system we developed to perform the
bin-picking task. Two basic tools are employed: the photometric
stereo method and the extended Gaussian image. The photometric stereo
method generates the surface normal distribution of a scene. The
extended Gaussian image allows us to determine the attitude of the
object based on the normal distribution. Visual analysis of an image
consists of two stages. The first stage segments the image into
regions and determines the target region. The photometric stereo
system provides the surface normal distribution of the scene. The
system segments the scene into isolated regions using the surface
normal distribution rather than the brightness distribution. The
second stage determines the object attitude and position by comparing
the surface normal distribution with the extended Gaussian image.
Fingers, with LED sensor, mounted on the Puma arm can successfully
pick an object from a pile based on the information from the vision part.
:end
:aim 727
:title {Analyzing the Roles of Descriptions and Actions in Open Systems}
:author Carl Hewitt and Peter de Jong
:asort Hewitt, C.; de Jong, P.
:date April 1983
:cost $1.50
:pages 15
:ADnum AD-A133614
:keywords open systems, concurrent system, message passing semantics,
distributed systems, lambda calculus, first order logic, actor theory,
description and action
:abstract
This paper analyzes relationships between the roles of descriptions
and actions in large scale, open ended, geographically distributed,
concurrent systems. Rather than attempt to deal with the complexities
and ambiguities of currently implemented descriptive languages, we
concentrate our analysis on what can be expressed in the underlying
frameworks such as the lambda calculus and first order logic. By this
means we conclude that descriptions and actions complement one
another; neither being sufficient unto itself. This paper provides a
basis to begin the analysis of the very subtle relationships that hold
between descriptions and actions in Open Systems.
:end
:aim 730
:title Fingerprints Theorems for Zero-Crossings
:author A.L. Yuille and T. Poggio
:asort Yuille, A.L.; Poggio, T.
:date October 1983
:cost $2.25
:pages 28
:adnum AD-A139181
:keywords zero crossings, scales, signal reconstruction
:abstract
We prove that the scale map of the zero-crossings of almost all
signals filtered by the second derivative of a gaussian of variable
size determines the signal uniquely, up to a constant scaling and a
harmonic function. Our proof provides a method for reconstructing
almost all signals from knowledge of how the zero-crossing contours of
the signal, filtered by a gaussian filter, change with the size of the
filter. The proof assumes that the filtered signal can be represented
as a polynomial of finite, albeit possibly very high, order. An
argument suggests that this restriction is not essential. Stability
of the reconstruction scheme is briefly discussed. The result applies
to zero- and level-crossings of linear differential operators of
gaussian filters. The theorem is extended to two dimensions, that is
to images. These results are reminiscent of Logan's theorem. They
imply that extrema of derivatives at different scales are a complete
representation of a signal.
:end
:aim 731
:title Structure From Stereo and Motion
:author Whitman Richards
:asort Richards, W.A.
:date September 1983
:cost $1.50
:pages 19
:abstract
Stereopsis and motion parallax are two methods for recovering three
dimensional shape. Theoretical analyses of each method show that
neither alone can recover rigid 3D shapes correctly unless other
information, such as perspective, is included. The solutions for
recovering rigid structure from motion have a reflection ambiguity;
the depth scale of the stereoscopic solution will not be known unless
the fixation distance is specified in units of interpupil separation.
(Hence the configuation will appear distorted.) However, the correct
configuration and disposition of a rigid 3D shape can be recovered if
stereopsis and motion are integrated, for then a unique solution
follows from a set of linear equations. The correct interpretation
requires only three points and two stereo views.
:end
:aim 732
:title Parts of Recognition
:author D.D. Hoffman and Whitman Richards
:asort Hoffman, D.D.; Richards, W.A.
:date December 1983
:cost $2.25
:pages 35
:abstract
A complete theory of object recognition is an impossibility -- not
simply because of the multiplicity of visual cues we exploit in elegant
coordination to identify an object, but primarily because recognition
involves fixation of belief, and anything one knows may be relevant. We
finesse this obstacle with two moves. The first restricts attention
to one visual cue, the shapes of objects; the second restricts
attention to one problem, the initial guess at the identity of an
object. We propose that the visual system decomposes a shape into
parts, that it does so using a rule defining part boundaries rather
than part shapes, that the rule exploits a uniformity of nature --
transversality, and that parts with their descriptions and spatial
relations provide a first index into a memory of shapes. These rules
lead to a more comprehensive explanation of several visual illusions.
The role of inductive inference is stressed in our theory. We
conclude with a precis of unsolved problems.
:aim 734
:title {The Computation of the Velocity Field}
:author Ellen C. Hildreth
:asort Hildreth, E.
:date September 1983
:cost $2.25
:pages 40
:keywords motion analysis, motion perception, computer vision,
image processing, velocity field
:abstract
The organization of movement in the changing retinal image provides a
valuable source of information for analyzing the environment in terms
of objects, their motion in space, and their three-dimensional
structure. A description of this movement is not provided to our
visual system directly, however; it must be inferred from the pattern
of changing intensity that reaches the eye. This paper examines the
problem of motion measurement, which we formulate as the computation
of an instantaneous two-dimensional velocity field from the changing
image. Initial measurements of motion take place at the location of
significant intensity changes as suggested by Marr and Ullman (1981).
These measurements provide only one component of local velocity, and
must be integrated to compute the two-dimensional velocity field. A
fundamental problem for this integration stage is that the velocity
field is not determined uniquely from information available in the
changing image. We formulate an additional constraint of smoothness
of the velocity field, based on the physical assumption that surfaces
are generally smooth, which allows the computation of a unique
velocity field. A theoretical analysis of the conditions under which
this computation yields the correct velocity field suggests that the
solution is physically plausible. Empirical studies show the
predictions of this computation to be consistent with human motion
perception.
:end
:aim 736
:title Hypothesizing Channels Through Free-Space In Solving the
Findpath Problem
:author Bruce R. Donald
:asort Donald, B.R.
:date June 1983
:cost $2.75
:pages 58
:ADnum AD-A133632
:keywords geometric modelling, robotics, obstacle avoidance, spatial reasoning,
computational geometry
:abstract
Given a polyhedral environment, a technique is presented for
hypothesizing a channel volume through the free space containing a
class of successful collision-free paths. A set of geometric
constructions between obstacle faces is proposed, and we define a
mapping from a field of view analysis to a direct local construction
of free space. The algorithm has the control structure of a search
which propagates construction of a connected channel towards a goal
along a frontier of exterior free faces. Thus a channel volume starts
out by surrounding the moving object in the initial configuration and
"grows" towards the goal. Finally, we show techniques for analyzing
the channel decomposition of free space and suggesting a path.
:end
:aim 737
:title Hidden Clues in Random Line Stereograms
:author H.K. Nishihara and T. Poggio
:asort Nishihara, H.K.; Poggio, T.
:date August 1983
:cost $1.50
:pages 9
:keywords random line stereograms, stereo matching, vision, vernier acuity,
frequency tuned channels, parallel processing, computer vision,
psychophysics
:abstract
Successful fusion of random-line stereograms with breaks in the vernier
acuity range has been previously interpreted to suggest that the
interpolation process underlying hyperacuity is parallel and
preliminary to stereomatching. In this paper (a) we demonstrate with
computer experiments that vernier cues are not needed to solve the
stereomatching problem posed by these stereograms and (b) we provide
psychophysical evidence that human stereopsis probably does not use
vernier cues alone to achieve fusion of these random-line stereograms.
:end
:aim 738
:title {Model-Based Recognition and Localization From Sparse Range or Tactile Da
ta}
:author W. Eric Grimson and Tomas Lozano-Perez
:asort Grimson, W.E.L.; Lozano-Perez, T.
:date August 1983
:cost $2.75
:pages 54
:keywords tactile recognition, robotics, range data
:adnum AD-A135791
:abstract
This paper discusses how local measurements of three-dimensional
positions and surface normals (recorded by a set of tactile sensors,
or by three-dimensional range sensors), may be used to identify and
locate objects, from among a set of known objects. The objects are
modeled as polyhedra having up to six degrees of freedom relative to
the sensors. We show that inconsistent hypotheses about pairings
between sensed points and object surfaces can be discarded
efficiently by using local constraints on: distances between faces,
angles between face normals, and angles (relative to the surface
normals) of vectors between sensed points. We show by simulation and
by mathematical bounds that the number of hypotheses consistent with
these constraints is small. We also show how to recover the position
and orientation of the object from the sense data. The algorithm's
performance on data obtained from a triangulation range sensor is
illustrated.
:end
:aim 739
:title Diagnostic Reasoning Based On Structure and Behavior
:author Randall Davis
:asort Davis, R.
:date June 1984
;pages 54
:cost $2.75
:abstract
We describe a system that reasons from first principles, i.e., using
knowledge of structure and behavior. The system has been implemented
and tested on several examples in the domain of troubleshooting
digital electronic circuits. We give an example of the system in
operation, illustrating that this approach provides several
advantages, including a significant degree of device independence, the
ability to constrain the hypotheses it considers at the outset, yet
deal with a progressively wider range of problems, and the ability to
deal with situations that are novel in the sense that their outward
manifestations may not have been encountered previously. As background
we review our basic approach to describing structure and behavior,
then explore some of the technologies used previously in
troubleshooting. Difficulties encountered there lead us to a number
of new contributions, four of which make up the central focus of this
paper. We describe a technique we call {\it constraint suspension}
that provides a powerful tool for troubleshooting. We point out the
importance of making explicit the assumptions underlying reasoning and
describe a technique that helps enumerate assumptions methodically.
The result is an overall strategy for troubleshooting based on the
progressive relaxation of underlying assumptions. The system can
focus its efforts initially, yet will methodically expand its focus to
include a broad range of faults. Finally, abstracting from our
examples, we find the concept of {\it adjacency} proves to be useful
in understanding why some faults are especially difficult and why
multiple different representations are useful.
:aim 740
:title {Extended Gaussian Images}
:author Berthold K.P. Horn
:asort Horn, B.K.P.
:date July 1983
:cost $2.75
:adnum AD-A135747
:keywords machine vision, attitude in space, shape representation,
object recognition, Gaussian image
:abstract
This is a primer on extended gaussian images. Extended gaussian
images are useful for representing the shapes of surfaces. They can
be computed easily from: (1) needle maps obtained using photometric
stereo, or (2) depth maps generated by ranging devices or stereo.
importantly, they can also be determined from geometric models of the
objects. Extended gaussian images can be of use in at least two of the
tasks facing a machine vision system: (1) recognition, and (2)
determining the attitude in space of an object. Here, the extended
gaussian image is defined and some of its properties discussed. An
elaboration for non-convex objects is presented and several examples
are shown.
:end
:aim 743
:title {Vertical Image Registration in Stereopsis}
:author K.R.K. Nielsen and T. Poggio
:asort Nielsen, K.; Poggio, T.
:date October 1983
:cost $1.50
:pages 13
:keywords stereopsis, image registration, vertical disparity
:abstract
Most computational theories of stereopsis require a registration stage
prior to matching to reduce the matching to a one-dimensional search.
Even after registration, it is critical that the stereo matching
process tolerate some degree of residual misalignment. In this paper,
we study with psychophysical techniques the tolerance to vertical
disparity in situations in which false targets abound - as in random
dot stereograms - and eye movements are eliminated. Our results show
that small amounts of vertical disparity significantly impair depth
discrimination in a forced-choice task.
:end
:aim 744
:title {Reconstructing a Depth Map from Intensity Maps}
:author Katsushi Ikeuchi
:asort Ikeuchi, K.
:date August 1983
:cost $1.50
:pages 19
:adnum AD-A135679
:keywords shape from shading, Marr-Poggio-Grimson stereo, needle map,
photometric stereo, depth map, intensity map
:abstract
This paper describes two methods for constructing a depth map from
images. Each method has two stages. First, one or more needle maps
are determined using a pair images. This process employs either the
Marr-Poggio-Grimson stereo and shape-from-shading, or, instead,
photometric stereo. Secondly, a depth map is constructed from the
needle map or needle maps computed by the first stage. Both methods
make use of an iterative relaxation method to obtain the final depth map.
:end
:aim 746
:title Picking Parts out of a Bin
:author Berthold K.P. Horn and Katsushi Ikeuchi
:asort Horn, B.K.P.; Ikeuchi, K.
:date October 1983
:cost $2.75
:pages 48
:adnum AD-A139257
:keywords machine vision, bin picking, shape representation,
object recognition, hand-eye system, attitude in space, extended Gaussian image
:abstract
One of the remaining obstacles to the widespread application of
industrial robots is their inability to deal with parts that are not
precisely positioned. In the case of manual assembly, components are
often presented in bins. Current automated systems, on the other
hand, require separate feeders which present the parts with carefully
controlled position and attitude. Here we show how results in machine
vision provide techniques for automatically directing a mechanical
manipulator to pick one object at a time out of a pile. The attitude
of the object to be picked up is determined using a histogram of the
orientations of visible surface patches. Surface orientation, in turn,
is determined using photometric stereo applied to multiple images.
These images are taken with the same camera but differing lighting.
The resulting needle map, giving the orientations of surface patches,
is used to create an orientation histogram which is a discrete
approximation to the extended Gaussian image. This can be matched
against a synthetic orientation histogram obtained from prototypical
models of the objects to be manipulated. Such models may be obtained
from computer aided design (CAD) databases. The method thus requires
that the shape of the objects be described, but it is not restricted
to particular types of objects.
:aim 747
:unavailable
:title A Structural Approach to Analogy
:author Hormoz Mansour
:asort Mansour, H.
:date November 1983
:pages 28
:keywords structural analogy, contextual analogy, knowledge
acquisition, nested frames, automatic acquisition
:aim 750
:title {Design Issues in Parallel Architecture for Artificial
Intelligence}
:author Carl Hewitt and Henry Lieberman
:asort Hewitt, C.; Lieberman, H.
:date November 1983
:cost $1.50
:pages 15
:adnum AD-A142482
:keywords architecture, parallelism, actors, Act2, artificial intelligence,
Apiary, message passing, reasoning
:abstract
Development of highly intelligent computers requires a conceptual
foundation that will overcome the limitations of the von Neumann
architecture. Architectures for such a foundation should meet the
following design goals: *) Address the fundamental organizational
issues of large-scale parallelism and sharing in a fully integrated
way. This means attention to organizational principles, as well as
hardware and software. *) Serve as an experimental apparatus for
testing large-scale artificial intelligence systems. *) Explore the
feasibility of an architecture based on abstractions, which serve as
natural computational primitives for parallel processing. Such
abstractions should be logically independent of their software and
hardware host implementations. In this paper we lay out some of the
fundamental design issues in parallel architectures for Artificial
Intelligence, delineate limitations of previous parallel architectures,
and outline a new approach that we are pursuing.
:aim 751
:title Analog "Neuronal" Networks in Early Vision
:author Christof Koch, Jose Marroquin, and Alan Yuille
:asort Koch, C.; Marroquin, J.L.; Yuille, A.L.
:date June 1985
:pages 17
:cost $1.50
:keywords analogy networks, analog-digital hardware, parallel computers,
surface interpolation, surface reconstruction, optimization problem,
regularization theory, early vision
:abstract
Many problems in early vision can be formulated in terms of minimizing
an energy or cost function. Examples are shape-from-shading, edge
detection, motion analysis, structure from motion and surface inter-
polation (Poggio, Torre and Koch, 1985). It has been shown that all
quadratic variational problems, an important subset of early vision
tasks, can be "solved" by linear, analog electrical or chemical
networks (Poggio and Koch, 1985). In a variety of situations the cost
function is non-quadratic, however, for instance in the presence of
discontinuities. The use of non- quadratic cost functions raises the
question of designing efficient algorithms for computing the optimal
solution. Recently, Hopfield and Tank (1985) have shown that networks
of nonlinear analog "neurons" can be effective in computing the
solution of optimization problems. In this paper, we show how these
networks can be generalized to solve the non-convex energy functionals
of early vision. We illustrate this approach by implementing a
specific network solving the problem of reconstructing a smooth
surface while preserving its discontinuities from sparsely sampled
data (Geman and Geman, 1984; Terzopoulos, 1984). These results suggest
a novel computational strategy for solving such problems for both
biological and artificial vision systems.
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