COMPUTER VISION
Computer Vision is a field of Artificial Intelligence(AI) that enables the computer and
systems to derive meaningful information from digital images, videos and other visual
inputs - and take actions or make recommendations based on that information. If AI
enables computers to think, computer vision enables them to see, observe and understand.
Eg, Computer vision is necessary to enable self-driving cars. Manufacturers such as Tesla,
BMW, Volvo and Audi use multiple cameras, lidar, radar and ultrasonic sensors to acquire
images from the environment so that their self-driving cars can detect objects, lane
markings, signs and traffic signals to safely drive.
APPLICATIONS OF COMPUTER VISION
1. Optical Character Recognition
2. Machine Inspection
3. Retail
4. 3D modelling building(photogrammetry)
5. Automotive safety
6. Match move
7. Motion capture
8. Surveillance
9. Fingerprint recognition and biometrics
HISTORY OF COMPUTER VISION
● Larry Roberts is commonly accepted as the father of computer vision.
● Computer Vision came into existence during the 1960’s
LEVELS OF HUMAN AND COMPUTER VISION SYSTEM :
Low Level Vision : Edge , Corner, Stereo reconstruction
Mid Level Vision : Texture, Segmentation and Grouping , illumination
High Level Vision :Tracking, Specific Object recognition , Category level object recognition
CAMERA PROJECTION
Projection : Projection is a technique or process which is used to transform a 3D object
into a 2D object in a projection plane or view plane. (representing an n dimensional object
into (n-1) dimension).
Projection is of two types:
1. Parallel projection
, 2. Perspective projection
Parallel projection are of two types orthographic and oblique. Orthographic projection can
be multiview or axonometric view. Axonometric view can be isometric, dimetric or
trimetric. Parallel projection another type is an oblique view, which is a general one. It is
of two types: cavalier or cabinet.
Perspective projection can be represented in one point, two point or three point.
How to transform a 3D world object to 2D picture ? Try to form a ray between our eyes
and a 3D object through a canvas. The ray hit the 3D object and bounced back to the
canvas and painted colors of the 3D object to 2D surface.
Parts help in transforming picture from 3D to 2D world :
Extrinsic Parameters - It includes the camera’s orientation i.e., Rotation(R) ,
Translation(T). The extrinsic parameters are the camera body configuration.
Intrinsic Parameters : Spatial relation between sensor and pinhole (K) , focal length (L). It
gives the transformation of the optical parameters.
Process of forming a 3D world object to a 2D picture : Imagine that we are an artist who
is going to draw a picture of the world. We’re standing in front of the canvas and looking
, into the world. The thing we do here is we try to form a ray between the eye and the point
in the world that we are seeing and now we pick any points that we want to draw in our
canvas. So, this ray that is being formed keeps the 3D world intersecting the points there
and bounds that object back into the canvas and then paints the color of the 3D object
into the 2D picture. So, that is the process of forming a 3D world object to a 2D picture.
Projection Equation : 3D to 2D image - f=focal length , c = focal distance { distance
between observer and the object}
PERSPECTIVE PROJECTION
Once those closest to us appear larger than the ones that are farther.
{Eg : Railway track }
Components Of Perspective :
Key things needed for the setup of perspective projection:
● Spectator (observer)
● Picture plane(plane that we are going to draw perspective image of object)
● Horizontal Line (The ray of light that finishes at horizontal line)
● Groundline
CENTER OF PROJECTION
It is the location of the eye on which projected light rays converge.
PINHOLE CAMERA
A pinhole camera is a simple camera without a lens but with a tiny aperture.
Camera that we use in daily life is not a canvas, it is a reverse canvas where the image
plane is in the backside of us .This is a pinhole model.
How to create Image : By taking Vanishing Point : Vanishing point is obtained by the
spectator looking parallel to whatever line he is looking at.
PROPERTIES OF LIGHT
Illumination :Property and effect of light. It is the amount of light incident on a surface
Luminance : Amount of visible light that come to eye from a surface
Refraction : bending of light rays when passing through a surface between one transparent
material to another
Reflectance : A portion of incident light that is reflected from a surface.
Computer Vision is a field of Artificial Intelligence(AI) that enables the computer and
systems to derive meaningful information from digital images, videos and other visual
inputs - and take actions or make recommendations based on that information. If AI
enables computers to think, computer vision enables them to see, observe and understand.
Eg, Computer vision is necessary to enable self-driving cars. Manufacturers such as Tesla,
BMW, Volvo and Audi use multiple cameras, lidar, radar and ultrasonic sensors to acquire
images from the environment so that their self-driving cars can detect objects, lane
markings, signs and traffic signals to safely drive.
APPLICATIONS OF COMPUTER VISION
1. Optical Character Recognition
2. Machine Inspection
3. Retail
4. 3D modelling building(photogrammetry)
5. Automotive safety
6. Match move
7. Motion capture
8. Surveillance
9. Fingerprint recognition and biometrics
HISTORY OF COMPUTER VISION
● Larry Roberts is commonly accepted as the father of computer vision.
● Computer Vision came into existence during the 1960’s
LEVELS OF HUMAN AND COMPUTER VISION SYSTEM :
Low Level Vision : Edge , Corner, Stereo reconstruction
Mid Level Vision : Texture, Segmentation and Grouping , illumination
High Level Vision :Tracking, Specific Object recognition , Category level object recognition
CAMERA PROJECTION
Projection : Projection is a technique or process which is used to transform a 3D object
into a 2D object in a projection plane or view plane. (representing an n dimensional object
into (n-1) dimension).
Projection is of two types:
1. Parallel projection
, 2. Perspective projection
Parallel projection are of two types orthographic and oblique. Orthographic projection can
be multiview or axonometric view. Axonometric view can be isometric, dimetric or
trimetric. Parallel projection another type is an oblique view, which is a general one. It is
of two types: cavalier or cabinet.
Perspective projection can be represented in one point, two point or three point.
How to transform a 3D world object to 2D picture ? Try to form a ray between our eyes
and a 3D object through a canvas. The ray hit the 3D object and bounced back to the
canvas and painted colors of the 3D object to 2D surface.
Parts help in transforming picture from 3D to 2D world :
Extrinsic Parameters - It includes the camera’s orientation i.e., Rotation(R) ,
Translation(T). The extrinsic parameters are the camera body configuration.
Intrinsic Parameters : Spatial relation between sensor and pinhole (K) , focal length (L). It
gives the transformation of the optical parameters.
Process of forming a 3D world object to a 2D picture : Imagine that we are an artist who
is going to draw a picture of the world. We’re standing in front of the canvas and looking
, into the world. The thing we do here is we try to form a ray between the eye and the point
in the world that we are seeing and now we pick any points that we want to draw in our
canvas. So, this ray that is being formed keeps the 3D world intersecting the points there
and bounds that object back into the canvas and then paints the color of the 3D object
into the 2D picture. So, that is the process of forming a 3D world object to a 2D picture.
Projection Equation : 3D to 2D image - f=focal length , c = focal distance { distance
between observer and the object}
PERSPECTIVE PROJECTION
Once those closest to us appear larger than the ones that are farther.
{Eg : Railway track }
Components Of Perspective :
Key things needed for the setup of perspective projection:
● Spectator (observer)
● Picture plane(plane that we are going to draw perspective image of object)
● Horizontal Line (The ray of light that finishes at horizontal line)
● Groundline
CENTER OF PROJECTION
It is the location of the eye on which projected light rays converge.
PINHOLE CAMERA
A pinhole camera is a simple camera without a lens but with a tiny aperture.
Camera that we use in daily life is not a canvas, it is a reverse canvas where the image
plane is in the backside of us .This is a pinhole model.
How to create Image : By taking Vanishing Point : Vanishing point is obtained by the
spectator looking parallel to whatever line he is looking at.
PROPERTIES OF LIGHT
Illumination :Property and effect of light. It is the amount of light incident on a surface
Luminance : Amount of visible light that come to eye from a surface
Refraction : bending of light rays when passing through a surface between one transparent
material to another
Reflectance : A portion of incident light that is reflected from a surface.
