Cartography Flashcards
the art and science of graphically representing a geographical area usually on a flat surface such as a map or chart. It may involve the superimposition of political, cultural, or other nongeographical divisions onto the representation of a geographical area.
Cartography
a symbolic representation of selected characteristics of a place, usually drawn on a flat surface
Map
shows a distance measured on the ground according to a certain proportion, and direction
Scale map
Basic elements of a scale map
Symbolsband legends
Scale
Direction
Map grid or coordinate system
About the map (date created, author, title, sources)
Shows shape and elevation of the land (topography)
Topographic maps
Vertical distance between two adjacent contour lines. Major and minor contours are shown depending on the scale of the map
CONTOUR INTERVAL
Relative scale
The larger the scale, the smaller the area
Uses words to describe the relationship between the map and the landscape
EQUIVALENCE SCALE
Typically represented as a ratio (1/50,000 or 1:50,000), indicates that one unit (inch, centimeter, football field or pitch, etc.) on the map represents the second number of that same unit on Earth.
REPRESENTATIVE FRACTION
is a bar marked off like a ruler with labels outlining the distances the segments represent.
graphical scale
THE NORTH ON A MAP
north is measured by a compass.
Magnetic North
THE NORTH ON A MAP
__ North follows the grid lines of the coordinate system the map is made on.
Grid north
THE NORTH ON A MAP
_ North corresponds to the Earths axis, the North pole
True north
A classification of map having scales ranging from 1:2000 to 1:10000.
Medium scale map
A classification of map having scales ranging from 1:10000 or smaller
Small scale map
A classification of map having scales 1:2000 or larger
Large scale map
Scale of a standard cadastral map
1:4000
Standard scale of a Municipal Base Map
1:60,000
Standard scale of a Provincial Base Map
1:400,000
Standard scale of a Regional Base Map
1:800,000
Photogrammetry is derived from three greek words meaning:
Photos: light
Gramma: drawn or written
Metron: measure
Distinct areas of photogrammetry
Metric photogrammetry
Interpretative photogrammetry
Classification of photographs
Terrestrial
Aerial
Extraterrestrial
: When the vertical photograph is taken it evident that optical axis of camera should be vertical or nearly vertical. (Tilt is within 3°).
Vertical orientation
Photograph is taken with strongly tilted optical axis but not to the extent that horizon appear in the photograph (horizon does not appear but tilt is more than 3°).
Low oblique:
: Photograph is taken with deliberately tilted optical axis enough from the vertical to show the Earth’s horizon (horizon appears in the photograph
High oblique
: Photograph is taken with camera axis horizontal.
Horizontal or terrestrial
It is a sequential pair of low oblique in which the optical axes converse towards one another. in this kind of photography both the photographs cover the same area but from different locations.
Convergent Photography:
is a function of focal length and format size
Angular coverage
Angle: Used for General interpretation, intelligence and mosaics
Narrow angle
angle: Up to 75°, used for general interpretation, mapping, ortho-photography, and mosaics.
Normal angle
angle: 75° to 100°, used for general interpretation, general purpose photography for normal terrain, resource mapping and mosaics
Wide angle
angle: over 100°, used for General purpose mapping of flat areas
Super-wide angle
Ttpes of film
Panchromatic
Colour
Infrared
Colour infrared
, more often termed black and white, is the most commonly encountered film employed for photogrammetry. The emulsion is sensitive to the visible (0.4- to 0.7-µm) portion of the electromagnetic spectrum.
Panchromatic
also known as true colour film. The multilayer emulsion is sensitive to visible region of electromagnetic spectrum
Natural colour/ colour
Current aerial __ film is offered as two types: black and white infrared and colour infrared
infrared film
___ film is commonly termed as false colour. The multilayer emulsion is sensitive to green (0.5-0.6 µm), red (0.6-0.7 µm), and part of the near infrared (0.7-1.0 µm) portions of the spectrum.
Colour Infrared film
made by joining several photographs taken at a single camera station usually by a multi-lens camera.
the result of a combination of vertical and oblique photography or only oblique photographs. The oblique photographs are all rectified, scaled to the vertical, and the mounted to give one whole picture of the area photographed.
Composite photographs
Two cameras are mounted on each side of the aircraft with the axis at right angles to the direction of flight. Exposures are taken simultaneously; the cameras are usually tilted from 5° to 7º from the vertical to give low oblique photographs
DUAL STRIP PHOTOGRAPHS (Twinned
Three cameras are employed during photography, one in the center which points vertically downward and the other two are tilted as in dual photography except that the tilt ranges from 7° to 10°. The additional tilt allows the tilted strips to just overlap the lateral edges of the vertical strip. It gives a larger coverage for photography.
TRIPLE STRIP PHOTOGRAPHS
The system has photographic units which consists of three wide angle cameras. One in vertical position and two in oblique positions and all three cameras are exposed simultaneously from the same aircraft.
TRIMETROGON PHOTOGRAPHS
These are precision instruments designed to take photographs from an aircraft
Aerial camera
___ is a light tight container which holds the supply of exposed and unexposed films. It has a supply spool and a take up spool, a mechanism for advancing the film after each exposure, and a device for holding the fil flat in the focal plane at the instant the exposure is made.
Magazine
is a one-piece casting which houses the drive mechanism for the shutter assembly and the magazine. It is the drive mechanism which provides the force to operate through each cycle
Camera body
-most important part of an aerial camera.
Lens
It gathers light ray from each point on the terrain and bring them into focus within the local plane behind the lens.
Lens
are pieces of colored glassed placed in front of the camera lens to prevent stray and undesirable lights from entering the camera.
Filter
Most common color filters used
Yellow orange red
- The physical opening of the lens system. It is positioned mid-way between the lens elements.
Diaphragm
Its function is to control the amount of light striking the emulsion of the film which is positioned in the focal plane.
diaphragm
Relationship of diaphram and shutter speed
Directly proportional.
When the diaphragm opening becomes larger, the shutter speed should be correspondingly greater.
Relationship of diaphram and angular field of view
Directly proportional
If a ray of light in the object space appears to is directed at the front ____, it is so bent or refracted, by the lens system that it emerge from the rear ____ without having undergone a change in its original direction.
Nodal points
controls the length of time that light is permitted to pass through the lens
Shutter
Are used to locate the principal point or geometric center of the photograph
Fiducial marks
Are used to locate the principal point or geometric center of the photograph
Fiducial marks
is defined as the point in the focal plane intersected by the optical axis of the lens. This point is important in reconstructing the geometry of the photograph
Principal point
The ___ of the camera is defined as the distance between the rear nodal point of the lens and the focal plane.
focal length
Classifications of focal length
Short focal length
Long focal length
when camera lens have less than 305mm (12”) focal length
Short focal length
provide wider ground coverage at a given flying height
Short focal length
Relationship of focal length and angular field of coverage
Inversely proportional
camera lens of more than 305 mm (12”) focal length
Ling focal length
angle measured at the apex of the usable cone of rays entering the camera lens
Angular field of view
is defined as the scale at the average elevation of the terrain covered by a particular photograph. This scale is given by the relationship
Average scale
This is the technique of measuring objects (2D or 3D) from photographs
Photogrammetry
It is to mainly used produce topographical or thematic maps and digital terrain models.
Aerial photogrammetry
Father of photogrammetry
Aime Laussedat
He developed the techniques for the documentation of buildings
Meydenbauer
The first institute for photogrammetry
Royal Prussian Photogrammetric Institute
He suggested the use of stereoscope to estimate volumetric measures
Ernst Mach
They presented the first stereoscopical instrument for vectorized mapping
Eduard Gaston
Daniel Deville
It is an instrument used for optical rectification
Perspectograph
He is the first to apply photogrammetry principles to aerial photographs
Theodore Sheimpflug
They have stable and precisely known internal geometries and very low lens distortions
Metric cameras
The line between two projection centers, if an object is photographed from two different positions.
Base
It consists of two metric cameras mounted at both ends of a bar
Stereometric camera
A cheap method of mapping which requires only a ruler, a pencil, and a piece of paper with a straight edge.
Paper-strip method
It uses photographic enlargers. Complies with the Scheimpflug condition and the vanishing point condition
Optical rectification
A commercially available camera
Amateur camera
A dense raster of points on the object with known distances from a reference plane
Digital Terrain Model
This technique is similar to numerical rectification, except that the coordinates are transformed into 3D coordinates
First bundle adjustment
The scanned image is transformed pixel by pixel into the 3D real-world coordinate system.
Digital rectification
A rectified photograph with a unique scale
Orthophoto
This photogrammetry instrument was first introduced in 1957
Diapositive
Defines how much a camera sees
Angular field of view
Refers to the measurement made on aerial photographs to obtain quantitative data of the earth’s surface.
Metric photogrammetry
Recognizing and identifying objects on the photograph, as well as judging their significance.
Interpretative photogrammetry
Recognizing and identifying objects on the photograph, as well as judging their significance.
Interpretative photogrammetry
Taken with ground-based cameras from known positions or stations with the camera axis horizontal or nearly so
Terrestrial photographs
The camera lend axis points at an angle on the ground
Oblique photograph
Made by joining several photographs taken at a single camera station usually by a multi-lens camera
Composite photographs
Three cameras are employed during photography, one in the center which piunts verticalky downward and the other two tilted
Triple strip photographs
Consists of a one-piece casting which houses the drive mechanism for the shutter assembly and the magazine
Camera body
Control the amount of light striking the emulsion of the film which is positioned in the focal plane
Diaphragm
Consists of colored glass placed in front of the camera lens to prevent stray and undesirable lught from entering the camera
Filter
Consists of colored glass placed in front of the camera lens to prevent stray and undesirable lught from entering the camera
Filter
