A New Omnidirectional A New Omnidirectional Vision Sensor for the Vision Sensor for the

Spatial Semantic Spatial Semantic HierarchyHierarchy

EE.. Menegatti Menegatti, M. Wright, E. , M. Wright, E. PagelloPagello

Dep. of Electronics Dep. of Electronics and Informaticsand Informatics

University of PaduUniversity of Padua a ITALYITALY

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

IntroductionIntroduction

Robot’s task: Robot’s task: Building a topological map of an Building a topological map of an

unknown environment;unknown environment;

Sensor:Sensor:Omnidirectional vision system;Omnidirectional vision system;

Work’s aim:Work’s aim:Prove effectiveness of omnidirectional Prove effectiveness of omnidirectional

sensors for Spatial Semantic Hierarchy;sensors for Spatial Semantic Hierarchy;

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Spatial Semantic Spatial Semantic Hierarchy...Hierarchy...

... A model of the human knowledge ... A model of the human knowledge of large spacesof large spaces

Layers:Layers:

–Sensory LevelSensory Level

–Control LevelControl Level

–Causal LevelCausal Level

–Topological LevelTopological Level

–Metrical LevelMetrical Level

Interface with the robot’s Interface with the robot’s sensory systemsensory system

Control Laws, Transition of Control Laws, Transition of State, Distinctiveness State, Distinctiveness

MeasureMeasure

View, Action, Distinct PlaceView, Action, Distinct Place

Abstracts Discrete from Abstracts Discrete from ContinousContinous

Minimal set ofMinimal set ofPlaces, Paths and RegionsPlaces, Paths and Regions

Distance, Direction, ShapeDistance, Direction, Shape

Useful, but seldom Useful, but seldom essentialessential

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Omnidirectional CameraOmnidirectional Camera

Composed of:Composed of: Standard Colour Standard Colour

Camera Camera Convex MirrorConvex Mirror Perspex CylinderPerspex Cylinder

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Pros e ConsPros e Cons

AdvantagesAdvantages

Wide vision fieldWide vision field

High speedHigh speed Vertical LinesVertical Lines Rotational Rotational

InvarianceInvariance

DisadvantagesDisadvantages

Low ResolutionLow Resolution

DistortionsDistortions

Low readabilityLow readability

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Omnidir. Vision and SSHOmnidir. Vision and SSH View Omnidirectional imageView Omnidirectional image

Discriminate b/t “Discriminate b/t “turns”turns” and “ and “travels”travels” Effective Distinctiveness measureEffective Distinctiveness measure

P2P2

P4P4 P3P3

P5P5

P1P1

–Exploring around the blockExploring around the block

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

AssumptionsAssumptions

Man-made environmentMan-made environment

Floor flat and horizontalFloor flat and horizontal

Wall and objects surfaces are verticalWall and objects surfaces are vertical

Static objectsStatic objects

Constant LightingConstant Lighting

Robot translates or rotatesRobot translates or rotates

No encodersNo encoders

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Features and EventsFeatures and Events

Feature:Feature:– Vertical EdgesVertical Edges

Events:Events:– A new edgeA new edge– An edge disappearAn edge disappear– Two edges 180° apartTwo edges 180° apart– Two pairs of edges 180° Two pairs of edges 180°

apartapart

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

ExperimentsExperiments

Tasks of Caboto:Tasks of Caboto: Navigation;Navigation; Map building;Map building;

Techniques:Techniques: Edge detection;Edge detection; Colour marking;Colour marking;

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Caboto’s ImagesCaboto’s Images

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

ResultsResults Correct tracking of edgesCorrect tracking of edges ReReccogniognization zation of of actionsactions Calculation of the turn angleCalculation of the turn angle

The path The path segmentationsegmentation

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Mirror DesignMirror Design

Design Design customcustom mirror profilemirror profile

Maximise resolution Maximise resolution

in ROIsin ROIs

Mirror ProfileMirror Profile

Mirror shape should depend on robotMirror shape should depend on robot task!task!

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Our new mirrorOur new mirror

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

ConclusionConclusion

Omnidirectional vision sensor is a Omnidirectional vision sensor is a good sensor for map building with good sensor for map building with SSHSSH

Egomotion of the robot was Egomotion of the robot was estimated without active visionestimated without active vision

The use of a mirror designed for this The use of a mirror designed for this application will improve the systemapplication will improve the system

E. Menegatti - A New Omnidirectional Vision Sensor for SSH

Omnidirectional CamerasOmnidirectional Cameras Compound-eye Compound-eye

camera camera (from (from Univ. of Maryland, College

Park. )

Panoramic cameras Panoramic cameras (from Apple)(from Apple)

Omnidirectional Omnidirectional camerascameras

(from (from University of Picardie - France)