PHOTOGRAMMETRY -GEP

Indirectly

The discipline of photogrammetry involves obtaining information about an object ________________, by measuring photographs taken of the object.

Intermediate medium

In photogrammetry, the object first recorded in_____________, such as photographs and images and the measurement are carried out later in the office.

Photogrammetry

art, science and technology of obtaining reliable information about physical objects and the environment through process of recording, measuring and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena

Metrical photogrammetry

Involves all quantitative work such as determination of ground positions, distances, differences in elevations, areas, volumes, various types of maps and other image and digital products such as orthophotos and digital elevation

Terrestrial Photogrammetry

Photographs are taken from fixed or known, points on or near the ground sometimes also called close range photogrammetry involving a camera relatively close to the object photographed

Aerial photogrammetry

Involves a high precision camera mounted in an aircraft and photographs are taken in organized manner as the aircraft flies over the terrain

Space photogrammetry

deals with extraterrestrial photography and imagery where the camera may be fixed on earth, mounted on board or a satellite, or located on a planet.

Interpretative photogrammetry

also called photo interpretation- involves the qualitative analysis of photographs for identifying objects and assessing their significance.

human ability

Photo interpretation relies on the ___________________ to correlate such photographic elements as sizes, shapes, patterns, tones, textures, colors, contrast, and relative locations

Photogrammetric imaging

it is a method of recording a two-dimensional view of three-dimensional object scene.

metric cameras

The conventional method used high quality ____________________ flown in an aircraft and recording the image on a photographic film.

passive and active

Image sensors are classified into-

Sensors

Significant technological advances in the field of remote sensing have allowed aircraft to carry _____________ and thus many new sources of imagery have emerged to supplement photography

Passive

___________________ system rely on the sun energy reflected or emitted from the scene

Active

_______________system generate their own energy source, send it to the scene, and record the returned signal.

electro-optical sensors

Passive systems are composed of cameras using film for recording and that__________________ record data on electronic media such as tape, diskette of solid estate memory.

Radar

an example of active systems for earth imaging

sonar

an example of active system for imaging under water

long-wavelength

Radar imager has the advantage of using _______________________ energy capable of penetrating clouds that render regular photography useles

night

radar can be used at ____________ and in all types of weather condition

film cameras

Most aerial film cameras used worldwide are

a.) between-the lens shutter

b.) focal-plane shutter

c.) illuminating the object for a short interval (night photography)

Exposure maybe controlled by means of

stationary

the film is held _______________ in the focal plane during exposure

fast-lens

Aerial film cameras, being in motion during exposure, require a _________________, a reliable shutter system for a very short exposure time, and a high-speed emulsion on the film.

cartographic cameras

aerial film cameras are also called _____________________ which are characterized by geometric stability and lenses that are connected for geometric distortion

Principal parts of an aerial frame camera

lens cone assembly (including shutter, diaphragm and filter) , camera body and magazine

lens cone assembly

contains the multi-element lens, shutter and diaphragm, and supports the frame that defines the focal plane.

90 degrees, 120 degrees

The lens is made of several elements provides for a larger angular coverage (about_________ for a wide angle and _____________ for super wide angle) and is corrected for abberations and distortions.

camera body

houses the drive mechanism, the drive motor, electrical connections and a recording chamber.

Motor

The _______________ and mechanism operate the shutter and film flattening device and advance the film between exposures.

recording chamber

allows for printing on each frame pertinent data such as level bubble, altimeter reading, clock, date, photo and mission numbers and camera number

focal plane

The cone and camera upper surface define the ___________________

fiducial marks

The focal plane registers _______________________, usually four on each photographic frame.

coordinate system

fiducial marks are important because they define the __________________________________ of the photograph

23

The most common type of aerial photographic format is square and measures _______ cm on each side.

infinity

the light entering an aerial camera lens is considered, for practical purposes, to come from ____________ due to the distance between the camera and terrain.

focal plane

the image of the terrain will be formed at the _______________ of the camera lens

focal length

the emulsion plane of the film is located at a distance from the lens equal to the____________________.

88mm
153mm
210mm
305mm

Focal lengths of aerial cameras are normally _________ mm, ______________ mm, __________ mm, and ____________ mm,

6

The _______ inch lens is the most common in photogrammetric mapping

Film Magazine

holds the unexposed and exposed film spools; it is light tight.

55, 150, 24

Magazines vary in capacity from ______ meters to _______meters of ______ cm wide thin base film

blue light

aerial cameras also provide filters that prevent some __________________ from reaching the film

vertical aerial photography

_____________________ is exposed such that camera optical axis is near vertical as possible during exposure

viewfinder

Other camera accessories include _______________(to provide the cameraman a clear unobstructed view of the terrain below and ahead of the airplane)

intervalometer

a timing device that can be set to trigger the camera shutter at a specified time interval between exposures

velocity-height computer

used to develop a voltage directly proportional to the aircraft velocity, V, and inversely proportional to its altitude H

color infrared film

For thematic mapping, especially of vegetation, ________________ is sometimes preferred.

panchromatic

aerial mapping film usually has __________________ (i.e., black and white) emulsion

film-based

color infrared film is still ____________________ sensing and is different from infrared thermal imaging, used in remote sensing, which requires a particular sensing system different from film.

Digital camera

it has a solid-state sensor (instead of a film as in analogue cameras) rigidly installed in the camera focal plane.

CCD (Change-Coupled Device)

The photo or imaging sensor of a digital camera is typically, a

CMOS (Complementary Metal Oxide Semiconductor)

The photo or imaging sensor of a digital camera is typically, a CCD (Change-Coupled Device) or ______________________________ chip

electrons

Both solid-state devices can convert light into ______________ that can be easily measured, resulting in a radiometric intensity value.

Sensor Arrays

Built by arranging individual sensor elements, pixels or picture elements into rectangular or linear formats on a silicone base.

a.) Stationary

b.) Airborne

c.) Space-borne

Imagery can be collected from three types of platforms:

Stationary

for terrestrial, industrial or close-range applications

Airborne

for low-altitude to high altitude jet aircraft, producing very large-scale to small imagery;

Space-borne

for sensors carried by earth orbiting satellites

Vertical

A ______________________ photograph is taken with the camera axis vertical, although unavoidable aircraft motion may cause tilt up to a few degrees from vertical.

Low Oblique

If the camera axis is intentionally tilted, as in small scale mapping, to increase the area covered by one photograph, the photograph is called a

high oblique.

When the tilt angle is large enough (50 degrees or 60 degrees) that the horizon appears in the photograph, it is called a

forward overlap

As the airplane flies over the ground, successive photographs are exposed in such a way that two adjacent photographs cover a common area that is more than half the single photo coverage. This common area called..

stereoscopic overlap

forward overlap, sometimes called ____________________ or simply overlap is usually between 55-66 percent.

Steriopair

An overlapping pair of photographs is called a

60, 20

Two successive photographs overlap about ___________ percent and three successive photographs by about ____________ percent

triple overlap

The 20 percent ___________________________ assures the proper connection from one pair of photographs to the next.

flight line

The line passing through the middle of successive photograph is called a

flight strips

set of photographs in one line

exposure stations

The position of camera at each exposure are called the ....

flying height

the altitude of the camera at exposed time is called the

sidelap, 30

Once the airplane has traversed the length of the project area. It turns around and returns in the opposite direction. The second strip of photography is exposed such that there is a ________________, normally __________ percent.

Block

The photographs of two or more sidelapping strips used to cover an area is called ___________ of photographs

latent

After an aerial photograph mission, the film is brought to the photo laboratory for processing. The images exposed on the film are called _____________ images, because these are not visible until these have been processed.

1. Panchromatic black and white (B&W)
2. Color
3. Infrared black and white (B&W IR)
4. Infrared color (false color IR)

Four types of emulsions are used in aerial photography

Panchromatic black and white (B&W)

The most widely use type

color

composed of three emulsion layers to render different color hues and used more for interpretation than in mapping

infrared black and white (B&W IR)

sensitive to near infrared light, thus penetrates haze and is used mainly for interpretation and intelligence work as it permits detection of camouflage

infrared color (false IR)

Different colors are arbitrarily used to code images from different portions of the light spectrum (thus the name false color), and used in interpretation such as crop disease detection, pollution monitoring and intelligence.

film negative

light portions of the original scene appear dark, while dark scene portions appear light

film positive

the original scene light and dark distribution is preserved