sensors on 3d digitization (1)

8/12/2019 Sensors on 3d Digitization (1)

1/24

SENSORS ON 3D DIGITIZATION


2/24

INTRODUCTION

SENSORS

3D IMAGING

3D DIGITIZATION

COMBINING SENSORS ON 3D

DIGITIZATION


3/24

COLOUR 3D IMAGING TECHNOLOGY

MACHINE VISION

PASSIVE VISION

ACTIVE VISION


4/24

Machine vision involves the analysis of

the properties of the luminous fluxreflected or radiated by objects. To

recover the geometrical structures of

these objects, either to recognize or to

measure their dimension, two basic

vision strategies are available.


5/24

Passive vision, attempts to analyze the

structure of the scene under ambient

light. Stereoscopic vision is a passiveoptical technique. The basic idea is that

two or more digital images are taken

from known locations.


6/24

Active vision attempts to reduce the

ambiguity of scene analysis by structuring the

way in which images are formed. Sensors

that capitalize on active vision can resolve

most of the ambiguities found with two-

dimensional imaging systems. Lidar based or

triangulation based laser range cameras areexamples of active vision technique.


7/24

COLOUR3D IMAGING TECHNOLOGY

TRIANGULATION TECHNIQUE


8/24

AUTOSYNCRONIZED SCANNER

TRIANGULATION BASED TECHNIQUE


9/24

SENSORS USED

SYNCHRONIZATIONCIRCUITBASED

UPON DUAL PHOTOCELLS

LASERSPOTPOSITIONMEASUREMENT

SENSORS


10/24

This sensor ensures the stability and the

repeatability of range measurements in

environment with varying temperature.

Discrete implementations of the so-called

synchronization circuits have posed many

problems in the past. A monolithic version of

an improved circuit has been built to alleviatethose problems


11/24

High-resolution 3D images can be acquired

using laser-based vision systems. With thisapproach, the 3D information becomes

relatively insensitive to background

illumination and surface texture. Complete

images of visible surfaces that are rather

featureless to the human eye or a video

camera can be generated


12/24

POSITION SENSITIVE DETECTOR

Position Sensitive Detector (PSD) is an

optical position sensor (OPS), that can

measure a position of a light spot in one or

two-dimensions on a sensor surface.The

PSD is a precision semiconductor optical

sensor which produces output currents

related to the centre of mass of lightincident on the surface of the device.


13/24

PSD camera detail


14/24

DUAL AXIS PSD

This particular PSD is a five terminal

device bounded by four collection

surfaces; one terminal is connected toeach collection surface and one

provides a common return. Photocurrent

is generated by light which falls

on the active area of the PSD will be

collected by these four perimeter

electrodes.


15/24


16/24

PROPSEDSENSOR

CONTINOUS RESPONSE POSITION

SENSITIVE DETECTORS (CRPSD)

DISCRETE RESPONSE POSITION

SENSITIVE DETECTORS (DRPSD)


17/24

PRPOSED SENSOR- COLOUR RANGE

ARCHITECHTURE


18/24

SENSORSON3DDIGITIZATION

ADVANTAGE:-

Reduced size and cost

Better resolution at a lower system cost

High reliability that is required for high accuracy

3D vision systemsComplete images of visible surfaces that are

rather featureless to the

human eye or a video camera can be generated

DISADVANTAGES:-

The elimination of all stray light in an optical

system requires sophisticated techniques.


19/24

Intelligent digitizers will be capable of

measuring accurately and

simultaneously colour and 3D For the development of hand held 3D

cameras

Multire solution random access laserscanners for fast search and tracking of

3D features


20/24

Anti reflecting coating film deposition

and RGB filter deposition can be used to

enhance sensitivity and for coloursensing.


21/24

The results obtained so far have shown that optical

sensors have reached a high level of development

and reliability those are suited for high accuracy 3D

vision systems. The availability of standard fabrication technologies

and the acquired know-how in the design techniques,

allow the implementation of optical sensors that are

application specific: Opto-ASICs. The trend showsthat the use of the low cost CMOS technology leads

competitive optical sensors.


22/24

A.M.DHAKE,Television and videoengineering, Tata Mc Graw Hill

for pointing devices, IEEE journal solid statecircuits, vol 31, pp

P.AUBERT, H.J.OGUEY, R.VUILLEUNEIR,Monolithic optical position encoder with on-chipphotodiodes,IEEE J.solid state circuits, vol23, pp.465-473, April 1988

K.THYAGARAJAN,A.K.GHATAK,Lasers-Theory and applications, Plenum Press


23/24


24/24

sensors on 3d digitization (1)

Documents