introduction of photogrammetry
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Introduction of PhotogrammetryTRANSCRIPT
Photogrammetry IPhotogrammetry I
Introduction to Photogrammetry
S.M.J.S.SamarasingheSuperintendent of Surveys
Institute of Surveying and Mapping
Diyatalawa- Sri Lanka
• Introduction to Photogrammetry: History of the development of Aerial Surveying. The Geometry of the titled photography.
• The characteristics of the Aerial Camera, Auxiliary equipment used in aerial Photography. Photographic mission planning. Understanding aerial photograph (Principle information etc…). Principles of stereoscopic vision, definition of parallax, the basic parallax formula.
• Stereoscopic Viewing methods, Distortions in a field photograph.
Lecture OutlineLecture Outline
Lecture OutlineLecture Outline
•Geometry of stereo pairs, Theory of orientation: Inner orientation, Relative orientation, Absolute orientation. •Problems in relative orientation due to topography.•Photogrammetric plotting Instruments (Analogue). Ground control.•Model Deformation. Numerical Relative Orientation. •Photographic coordinate system. Mono comparator, Stereo comparator measurements of photo coordinates, Transformation. •Elementary methods of planimetric mapping with vertical photographs. Field compilation and map making.
Text BookText Book
Elements of Photogrammetry- Second edition , Author: Paul R. Wolf
ActivitiesActivitiesLecture Hours 30Practical & Tutorial Hours 15
Final Exam 80%Assignments and quizzes 20%
100%
Grade PolicyGrade Policy
EvaluateEvaluate
Introduction
Definitions:
Remote Photogrammetry
”The science or art of obtaining reliable measurements by means of photographs.”
”Photogrammetry is the art, science, and technology of obtaining reliable information about physical objects and the environment through the processes of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant energy and other phenomena.” (ASPRS, 1980)
DefinitionDefinition
Why Photogrammetry………
RAF's wartime reconnaissance photos -archive
Dramatic pictures illustrate Allied assault on D-Day and bombing raids over Germany
Analog PhotogrammetryAnalog PhotogrammetryUsing optical, mechanical and electronical components,
and where the images are hardcopies. Re-creates a 3D model for measurements in 3D space.
Analytical PhotogrammetryAnalytical PhotogrammetryThe 3D modelling is mathematical (not re-created) and
measurements are made in the 2D images.
Digital PhotogrammetryDigital PhotogrammetryAnalytical solutions applied in digital images. Can also
incorporate computer vision and digital image processing techniques.
or Softcopy Photogrammetry”Softcopy” refers to the display of a digital image, as
opposed to a ”hardcopy” (a physical, tangible photo).
Photogrammetry………
Photograph ImageA scene which was detected as well as recorded on film.
A scene which was detected
electronically.
Chemical reactions on a light sensitive film detects the intensity of the incoming energy.
Generate an electrical signal
proportional to the incoming
energy.
Simple, cheap, well known. Can sense in many wavelengths,
data can be easily converted
into digital form for automated
processing.
Only sense in the wavelength of
0.3 – 0.9 μm, manual interpretation.
Complex,
Expensive sensors
Photograph vs. Image
Relationships of the Mapping Sciences as they relate to Mathematics and Logic, and the Physical, Biological, and Social Sciences
History
History of Aerial Photography:
HistoryHistory
HistoryHistory
Origins of Remote Sensing
First photographs taken in 1839
Remote sensing began withaerial photography
HistoryHistory
1858 Gasper Felix Tournachon "Nadar" takes photograph of village of Petit Bicetre in France from
a balloon.
Paris by Nadar, circa 1858
HistoryHistory
Boston by Black and King (1860)
HistoryHistory
World War One was a major impetus to development of aerial photography
HistoryHistory
After the war the technology was in place to begin large scale aerial surveys
A brief history of Photogrammetry
A brief history of Photogrammetry
A brief history of Photogrammetry
Why Photogrammetry………
Measuring values and camera constants
Why Photogrammetry
•Extracting geometrical information and producing maps.
•Cheaper than terrestrial methods.
•Extracting qualitative information.
•High speed of map generation.
Why Photogrammetry………
Ideal technology when measuring objects such as
– Vast regions to be mapped – Irregular shapes and
– Objects that are too • Hot or cold • Soft • Delicate • Inaccessible • Toxic • Radioactive to touch
Photogrammetric products
Planimetric maps –
Planimetric elements in geography are those features that are independent of elevation, such as roads, building footprints, and rivers and lakes. They are represented on two-dimensional maps as they are seen from the air, or in aerial photography. These features are often digitized from orthorectified aerial photography into data layers that can be used in analysis and cartographic outputs.
Topographic maps –
A type of map characterized by large-scale detail and quantitative representation of relief, using contour lines. Traditional definitions require a topographic map to show both natural and man-made features. A topographic map is typically published as a map series.
Photogrammetric products……
3D points
LiDAR has become the technology of choice for deriving highly accurate terrain data and 3D models, and it is commonly used for a variety of mapping applications.
Photogrammetric products……
Photomap (Orthophotos)
DEM/ DTM
DSM
General Process
General Flow
Real World(Earth)
Sensor (Camera)
Data Source(Images)
Image Refinement& measurement
Refined Image
Observation
Products•Maps•DEM
•Otrthophoto
Mathematical Models
Decision Making
Data Analysis
Production Line Mapping Using Aerial Photogrammetry Production Line Mapping Using Aerial Photogrammetry
Photogrammetric Types
Photogrammetric Types from Applications Point of View (d is distance from camera to object)
Close Range Photogrammetry d<10 m
Terrestrial Photogrammetry 10 m<d<100 m
Aerial Photogrammetry 2 km<d<10 km
Space Photogrammetry 30 km<d
Photogrammetric Types
Close Range Photogrammetry
Terrestrial Photogrammetry
Taken with ground-based cameras
Position and orientation often measured
Terrestrial Photogrammetry
Aerial Photogrammetry
Space Photogrammetry
Extraterrestrial pictures taken from space-based cameras
Extraterrestrial
Spot Image
Space Photogrammetry
Space Photogrammetry
Extraterrestrial
NOAA Image
Extraterrestrial
Ikonos Image
Space Photogrammetry
Types of Images
• Panchromatic, Black & White, Grayscale
• Color RGB
• Multispectral
• Hyperspectral
Panchromatic Image
Black and white Image
Grayscale Image
True Color composite image
False Color composite image
Types of photographs (categorized by tilt)
• Vertical - camera axis as nearly vertical as Possible
• Oblique - camera axis intentionally tilted• Low Oblique• High Oblique
Types of photographs
TerrestrialAerial
Vertical
Oblique
Truly Vertical
Tilted
(1deg< angle < 3deg)
High oblique
(includes horizon)
Low oblique
(does not include horizon)
Vertical Aerial Photogrammetry
Mainly used for mapping
Low Oblique
Low oblique (no horizon)
High Oblique
• Horizon line in the photo
Vertical aerial images are not map!
• Maps are based on parallel projection while photo has central projection
• Maps have a unique scale while image scale varies depending on terrain relief
• Maps are interpreted while photos should be interpreted
• Photo is detailed while maps are generalized
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Projection systems
Taking photographs
Taking Vertical Aerial Photographs
• Photos taken in parallel flight strips
Taking Vertical Aerial Photographs
• Each successive photograph overlap previous photo
Forward Overlap (End Lap)
Aerial Photography Stereo pair
•Over lap about 60%
Aerial Photography – Stereo pair
•Over lap about 60%
•Aerial Base: the distance between two successive projection centers
Side Overlap (Side Lap)
Taking Vertical Aerial Photographs
• Position of camera at each exposure called exposure station
• Flying height – altitude of camera• Adjacent flight strips overlap – side
overlap• Block of photos – photos of 2 or more side
lapping strips
Block of photographs
Projection Plotters
MULTIPLEX MODEL SKETCH
Direct Optical Projection Stereo plottersDirect Optical Projection Stereo plotters
Nistri Photomultiplex
Model D III
Kelsh Stereoplotter
Direct Optical Projection Stereo plottersDirect Optical Projection Stereo plotters
Kern PG-2 analog stereo-plotter.
Direct Optical Projection Stereo plottersDirect Optical Projection Stereo plotters
Kern PG-3 analog stereo-plotter, Switzerland
Direct Optical Projection Stereo plottersDirect Optical Projection Stereo plotters
Wild A-10 analog stereo-plotter.
Direct Optical Projection Stereo plottersDirect Optical Projection Stereo plotters
Digital systems require that the aerial photographs be scanned as high-resolution images.
Digital systemsDigital systems
END