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ACTINIC LIGHT RAYSThe invisible, chemically active light rays which act on photographic emulsions.
AERIAL PHOTOGRAPHA photograph of a portion of the earth's surface, taken from an aircraft. There are two principal types of photographs; vertical (the camera lens is parallel to the ground below) and oblique (lens is purposely titled from the vertical, generally 30–60 degrees).
AERONAUTICAL CHARTA map of the earth's surface, designed for aviation use. Depicts necessary topographic information, aids to navigation and obstructions.
ALGORITHMA set of well-defined rules for the solution of a problem in a finite number of steps.
ALPHANUMERIC CHARACTERSComputer coded characters which represent numerals or letters of the alphabet.
ARTWORKDrawings, overlays, etc., prepared for reproduction of maps or graphics.
AUTOPOSITIVEA class of photographic material which yields a positive image from a positive original without an intermediate negative stage.
AZIMUTHThe angular distance in a horizontal plane measured clockwise from true north to a given course or celestial object.
BACKLIGHTLight passed through a clear or translucent copy from behind the image in photographic reproduction.
BANDA selected range of wavelengths of the electro-magnetic spectrum.
BAR SCALEA line or parallel lines divided at specific intervals indicating map distances in relation to earth distances.
BASE MAPA map containing geographic information for purposes of referencing study data and displaying its distribution and inter-relationships.
BATHYMETRIC CHARTA map showing water depths and underwater topography, often in various shades or colours.
BEARINGDirection of a line with reference to the cardinal points of the compass.
BENCH MARKAn accurately established elevation point in relation to chart datum.
BUOYA floating object, moored or anchored to the sea bottom, used as an aid to navigation or as a floatation device.
CADASTRAL MAPLarge-scale maps indicating subdivisions, townships, and exact positions and dimensions of properties.
CARTOGRAPHYThe art, science and technology of making maps and charts and their study as scientific documents and works of art.
CHANNEL(1) The part of a body of water deep enough for navigation;
(2) The deepest part of a stream, bay or strait through which the main current flows;
(3) A band of radio frequencies within which a radio station must remain to prevent interference.
CHROMAThe range from neutral grey to full saturation of a single colour hue.
COLOUR SEPARATION(1) The mechanical and hand process of separating artwork destined to be coloured into negative overlays or components for each of the printing colours; (2) The optical process of separating coloured artwork by means of colour filters into separate single-colour negatives for each of the subtractive primary colours.
COMPILATIONThe assembly of source material such as aerial photographs, photogrammetric information, surveys and data taken from existing maps.
COMPOSITE PRINTReproduction of two or more images on a single base.
CONJUGATE PRINCIPAL POINTThe photographic position on an aerial photograph of the principal point of the adjoining photograph.
CONTACT PRINTA photographic reproduction made from a negative or positive in contact with sensitized paper, film or printing plates in a vacuum frame and therefore produced at an identical size.
CONTINUOUS-TONEA photographic image which contains a smooth and continuous transition of tones from black to white.
CONTOURAn imaginary line connecting points on the land surface or sea floor of the same elevation or depth respectively.
CONTOUR INTERVALThe difference in elevation between adjacent contours.
CONTRAST (Photography)The difference in value or tone between highlight and shadow (background) on an image.
CONTROLSystem of accurate measurement used to obtain distances and directions. The specific controls are classified as follows:

(1) Horizontal, relating to parallels and meridians;
(2) Vertical, relating to elevations;
(3)Astronomic, relating to the solar system;
(4) Ground, relating to photogrammetry;
(5) Recovered, identified from other sources.
COORDINATES (Grid)System for locating points on the earth's surface by means of a rectangular grid super-imposed and keyed to a map projection.
COPYTerm used in the printing industry to refer to any material such as photographs or artwork which will be reproduced.
CRTCathode Ray Tube - a video display.
CULTURAL FEATURESMap features that have been built or established by man. These include: roads, dams, canals, bridges, boundaries, etc.
CYANOne of the subtractive primary colours which is used in the four colour printing process. It reflects blue and green light and absorbs red light.
DATA BASEA store of information, usually in digital form, organized so that retrieval can be done on a selective basis.
DATUMA reference, such as a line, or plane, in relation to which the position of other elements is determined.
DENSITOMETERAn instrument for measuring the amount of transmitted or reflected light.
DENSITYThe degree of darkness (light absorption or opacity) of a photographic image.
DEVELOPERThe chemical agent and process used to render photographic images visible after exposure to light.
DIAPOSITIVEA transparent positive on a stable base.
DIAZOA process normally used for reproduction in contact printing techniques or to provide a light sensitive coating for proofs and plates.
DIFFUSION TRANSFERA system which consists of a photographic emulsion on which a temporary negative is produced. A chemical or activator softens the unexposed image parts and a positive image is transferred to a receiver sheet during processing.
DIMENSIONAL STABILITYThe ability to maintain size; the resistance of paper or film to dimensional change due to variations in temperature or humidity.
DISPLACEMENTA shift in the position of an image on an aerial photograph due to tilt, local variations in relief or scale changes.
DRYING HEIGHTSThe height above the sounding datum of rocks and banks that cover and uncover with tidal fluctuations.
DUPLICATING FILMA film for making positives from positives, and negatives from negatives.
ECHO SOUNDERA device which measures the time it takes a sound signal to travel from a ship to the ocean floor and back. This is converted into a depth reading.
EDITINGChecking a map in its various stages of production to insure correct interpretation of the data sources used and final appearance before reproduction.
ELECTROMAGNETIC SPECTRUMThe range of electromagnetic radiation from the shortest cosmic rays, through gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and all longer radio wavelengths.
ELECTROPHOTOGRAPHYImage transfer systems used in copiers to produce images using electrostatic forces.
ELEVATIONVertical distance above sea level.
ELEVATION TINTThe layer of colour between selected and general contours, according to altitude.
ELEVATION TONESA method of accentuating the elevation expressed by the contours through the use of different tones of the same colour.
ELLIPTICAL DOTIn halftone reproduction, elongated dots which give improved gradation of tones, particularly in middle tones and vignettes.
EMA square measurement in type composition which equals the width and height of the point size being set. So named because the letter “M” in early fonts was usually cast on a square body.
EMULSIONA suspension of light sensitive materials such as silver halides, in a colloidal substance (usually gelatin), which is used to coat photographic films, plates and papers.
ENOne half the width of “em”.
EQUAL AREAApplied to maps showing areas correctly throughout the map.
EQUIDISTANTApplied to maps which have selected lines along which distances, or scale, can be measured correctly.
EXPOSUREThe step in photographic processing during which light produces the image on the light-sensitive emulsion. “
“F” STOPSIn photography, fixed stops for setting lens apertures and controlling the light entering a lens and shutter system.
FALSE COLOUR FILMFilm that does not record the blue light reflected from a subject but instead registers the green, red and infrared radiation it reflects. This produces an abnormal coloured image.
FEATURE SEPARATIONThe process of preparing a separate piece of artwork or negative for only selected portions of the data on a complex map.
FILTERA transparent medium that absorbs specific regions of the spectrum and transmits other portions.
FIXINGChemical action following development to remove unexposed light sensitive materials from a film. This makes the image stable and insensitive to further exposure.
FLASH EXPOSUREIn halftone photography, the supplementary exposure given to strengthen dots in the shadow areas of negatives.
FLATIn printing, the assembled composite of negatives or positives ready for platemaking.
FLATBED PLOTTERA digital plotter in which the output material is mounted on a flat surface.
FLIGHT LINEThe path that an aircraft or other airborne sensor follows when collecting data.
FOCAL LENGTHIn photography, the distance measured along the optical axis from the optical centre of the lens to the film plane, measured when the lens is focused at infinity.
FONTIn type composition, a complete assortment of letters, numbers, punctuation marks, etc., of a given size and design.
FORESHOREThe intertidal zone of a beach.
FORM LINESLines that represent contours that are sketched to show the shape of the terrain rather than elevation.
GEODESYThe science which considers the size and shape of the earth on a mathematical basis.
GEODETICBasic relationship of the earth to the curvature of its sea level surface.
GRADIENTThe rate of change of a variable quantity.
GREY SCALEA strip of standard grey tones, ranging from white to black, placed at the side of original artwork during photography to measure tonal range and contrast obtained on the copy.
GRIDNetwork of lines on a plane surface upon which coordinates are based and to which the map features are referenced.
GUIDE IMAGEImage obtained on scribing film by a photo-chemical method. The image is used as a guide for scribing.
GUTTERThe blank space or inner margin, from printing area to binding on a page.
HACHURELine symbol used to indicate land formations on maps.
HALATIONThe spreading of light beyond its proper boundaries in a developed photographic image.
HALFTONEA continuous-tone image such as a photograph, reproduced through a crossline or contact screen, which converts the image into dots of various sizes.
HICKEYSIn printing (offset), spots or imperfections caused by dirt or other particles on the printing plate.
HISTOGRAMA graphic display of information which shows the frequency of occurrence along the vertical axis and the individual values along the horizontal axis.
HOMOLOGRAPHICApplied to maps showing the same graphic representation.
HUEThe characteristic of a colour associated with a wavelength of light which distinguishes it from other colours.
HYDROGRAPHIC CHARTA chart showing water features such as depths, channels, islands and other aids to navigation.
HYDROGRAPHYScience which deals with the measurement and description of physical features of the oceans, lakes and rivers and their adjoining coastal areas.
HYPOAn abbreviation for sodium thiosulfate or sodium hyposulphite, a chemical used to fix the image on a photographic film after it has been developed.
HYPSOMETRYVertical control in map making with reference to elevation relative to an established datum.
INFRARED RADIATIONEnergy in the 0.7–100 micrometres (microns) area of the electromagnetic spectrum. “Invisible light”, longer than visible light, is known as the near infrared. This can be recorded on photosensitive materials. Far infrared radiation is often termed “thermal infrared” and must be recorded by electronic means.
INTENSITYThe richness or brilliance of a colour.
ISOTHERMA line connecting points of equal temperature.
ITALICThe style of letters that slant, in contrast to the normal upright or Roman form. Used for emphasis in text and commonly to refer to water features on maps.
JUSTIFYIn type composition, to space out lines uniformly to a predetermined length.
KERNINGIn type composition, the subtraction of space between letters or characters so that they appear closer together and form a visual unit.
KEYLINEAn outline drawing of finished artwork to indicate the exact shape, position and size for each of the basic elements in the design.
LANDMARKA conspicuous man-made or natural feature that may be of assistance to a mariner for determining position.
LARGE-SCALEScale of 1:25,000 or larger (1:10,000, 1:5,000, etc.). The smaller the number, the larger the scale.
LASERAcronym for Light Amplification by Stimulated Emission of Radiation. An intense light beam with very narrow band widths.
LAYOUTThe drawing or sketch of a proposed piece of artwork.
LEADINGIn type composition, the distance between lines of type, measured in points.
LETTERSPACINGThe placing of additional space between each letter of a word.
LINE MAPMap composed of point, line and area symbols as contrasted to continuous-tone images.
LITH FILMA high contrast, orthochromatic film used traditionally for photomechanical work.
LORANAcronym for Long Range Navigation. A system using pulsed, low frequency radio waves.
LOWER CASEThe small letters in type, as distinguished from capital letters.
MAGENTAOne of the subtractive primary colours which is used in four colour process printing.
MAGENTA SCREENA dyed contact screen, used for making half-tones.
MANUSCRIPTOriginal drawing of a map as compiled from various data sources.
MAPA graphic representation of the earth's surface drawn to an established scale on a plane surface.
MARGINThat area of a map or chart lying outside the border, also known as “surround”.
MARGINAL INFORMATIONThe explanatory notes, diagrams and scales shown in the map margin.
MASKINGIn photomechanical processing, the blocking out of an area by means of actinically opaque material to prevent exposure in the blocked out area.
MEANA statistical term meaning the average value of a data set.
MERIDIANA north-south line connecting the poles.
MOIREThe undesirable screen pattern of light and dark patches caused by overlapping screens printed at incorrect angles.
MOSAICTwo or more overlapping aerial photographs assembled together.
NADIRIn aerial photography, the point vertically beneath the perspective centre of the camera lens.
NANOMETERA unit of length, one billionth of a metre or 1 x 10-9 m. Also known as a millimicron.
NAUTICAL CHARTHydrographic or marine map.
NAVSTAR-GPSAcronym for Navigational Satellite Timing And Ranging - Global Positioning System; a system of 18 satellites offering precision navigation.
NEATLINEThe inner border of a map.
NEGATIVEAn image formed of lines and symbols which allow the passage of light on a background which is opaque to light.
OPAQUEImpervious to the rays of light. Opaque also refers to a variety of substances that prevent transmission of light.
OPEN WINDOW NEGATIVEA negative having open areas in which solids, screens, rulings and tints of a colour may be printed.
ORTHOCHROMATICPhotographic materials insensitive to red light but recording ultraviolet, blue, green and yellow light.
ORTHOPHOTOImage derived from aerial photographs by differential rectification so that all scale errors have been removed.
OVERLAYA transparent or translucent material which is fitted or registered over the base map in use for the purpose of adding information.
OVERPRINTNew information printed on an existing map or chart to show data of importance or additions to those originally printed.
PANCHROMATIC FILMPhotographic film sensitive to all visible colours of light.
PARALLAXThe apparent change in the position of one object relative to another when seen from a different location.
PASS POINTSPoints determined from photographs by photo-grammetric methods for use in orientation of other aerial photographs.
PHOTO ENGRAVINGPhotomechanical process for converting any object that can be photographed into a relief plate for letterpress printing.
PHOTO MAPAn unrectified reproduction of an aerial photograph or a mosaic made from several aerial photographs for the purpose of depicting geographic and/or thematic information.
PHOTOGRAMMETRYMethod of obtaining accurate measurements from aerial photographs.
PHOTOGRAPHGeneral term for a positive or negative print on various support materials produced by several reproductive methods.
PHOTOMECHANICAL TRANSFER (PMT)A diffusion transfer copying process which produces high contrast images on film or paper in line or halftone.
PICAA unit of type measurement used in type-setting. One pica is approximately 1/6 inch.
PIN REGISTRATIONThe use of accurately positioned holes and special pins on artwork, films and plates to ensure proper registration and fit of components and overlays.
PLANIMETRIC MAPMap indicating only the horizontal positions of features without regard to elevation.
POINTA unit of type measurement. There are 12 points to a pica and approximately 72 points to one inch.
POSITIVEAn image formed of lines and symbols which are opaque to light on a background which either allows all light to pass through (transparency) or reflects all light (a white background).
PRESS PROOFA map proved on a printing press or taken from the first printed copies for editing purposes.
PROCESS COLOURSThe subtractive primaries, yellow, magenta and cyan plus black used in four colour process printing.
PROGRESSIVE PROOFS (Progs)Proofs made from the separate plates in colour process printing, showing the sequence of printing and the result after each additional colour has been applied.
PROJECTIONA system of lines on a map representing a series of imaginary lines on the earth's surface.
PROOFA preliminary single or multi-colour copy of a map, chart or graphic produced by photo-mechanical processes for the purpose of editing and correction, and to show final appearance before printing.
PROVISIONAL MAPA rapidly produced map that sacrifices accuracy for speed of production.
RADARAcronym for Radio Detection and Ranging; an instrument using beamed and timed electro-magnetic radiation to detect or track objects, measure height or obtain an image of the surface.
RAGGED LEFTIn typesetting, text that is aligned on the right and ragged on the left edge.
RAGGED RIGHTIn typesetting, text that is aligned on the left and ragged on the right edge.
REFLECTION COPYA copy of artwork produced on opaque materials which must be photographed by light reflected from its surface.
REGISTERThe correct position of one component of a composite image in relation to the other components.
REPROGRAPHYCopying and duplicating.
REVERSE LETTERINGLight lettering on a dark background.
REVERSE READING OR WRONG READINGAn image readable in a normal way (left to right) when viewed from the non-emulsion side of a film copy.
RIGHT READINGAn image readable in a normal way (left to right) when viewed from the emulsion side of a film copy, plate or paper print.
SAFELIGHTA special darkroom lamp used for illumination without fogging sensitized materials.
SANS SERIFA typeface without serifs.
SCALEThe ratio of distance measured on a map to the corresponding distance on the ground.
SCREENSheet of transparent film or glass carrying a regularly repeated pattern which may be used in conjunction with an area negative to photo-mechanically reproduce areas of the pattern.
SCREEN ANGLEAngle at which halftone screens or screen tints for each colour are printed in relation to one another to avoid moire patterns. Angles normally used are black 45°, magenta 75°, yellow 90°, cyan 105°.
SCREEN, HALFTONEA variable opacity screen used to convert continuous-tone to varying size dots.
SCREEN RULINGThe number of lines or dots per inch on a halftone screen or screen tint.
SCREEN TINTA screen of closely and evenly spaced dots or lines used on open window negatives to produce tones.
SCRIBING FILMA transparent base which carries an actinically opaque coating that can be removed by scribing to produce open images. The finished scribe-sheet can be used as a photographic negative in the photomechanical processes.
SEISMOMETERA device for recording data on the structure of the earth's crust by recording small sounds, obtained from distant earthquakes or man-made sources. An Ocean Bottom Seismometer (OBS) records data from the ocean bottom.
SENSORA generic name for a device that senses either the absolute value or a change in a physical quantity such as temperature or salinity and converts that change into an input signal for an information gathering system.
SERIFThe short cross-lines at the ends of the main strokes of many letters in some type faces.
SHORELINEOn charts this represents the line of contact between the land and a selected water elevation.
SIDELOOKING RADARAn all-weather, day or night remote sensor. It is defined as an active sensor; it generates its own energy, which is transmitted and reflected from the ground target area in the form of a photo-like picture. Also known as Side-Looking Airborne Radar or SLAR.
SIDE-SCAN SONARAn acoustic device which sends out a beam of sound waves laterally from a ship's course to map the seabed topography in broad swaths.
SPECTRAL SIGNATUREQuantitative measurement of the detected properties of an object at several wavelengths.
SPECTRUM (Light)The complete range of colours in the rainbow, from short wavelengths (blue) to long wavelengths (red).
SPECTRUM (Radiation)A series of radiation wavelengths sequentially arranged.
STABILIZATION PROCESSA rapid-access photographic process which uses special paper in which a developing agent is incorporated into the emulsion layer, allowing fast development.
STANDARD DEVIATIONThe square root of the arithmetic mean of the squares of the deviations from the mean. A measure of the dispersion from the mean in a frequency distribution.
STEREOGRAPHICHaving a visual three-dimensional appearance.
STEREOSCOPIC FUSIONThe mental process which combines the two perspective images on the retinas of the eyes in such a manner as to give a mental impression of a three-dimensional model.
STEREOSCOPIC MODELAn optical three-dimensional reconstitution of an object by means of superimposed projected images of a stereoscopic pair, or the viewing of the pair of photographs with the aid of a stereoscope.
STEREOSCOPIC PAIRTwo aerial photographs of the same area taken from different camera stations. A portion of the same area appears on both photographs.
STRIPPING FILMThin photographic film which, after exposure, may be removed from its base support and transferred to any suitable medium, using a thin layer of wax as an adhesive.
TELEMETRYThe science involved with measuring a quantity, and transmitting this value to a station for interpretation or recording of the quantity.
THEMATIC MAPPERA multispectral scanning system with seven channels of operation.
TILTThe angle between the optical axis of a camera and a plumb line.
TINTSEven-toned area of a colour.
TOOTHThe slightly rough finish of paper or plastics which permits ink to adhere to the surface.
TOPOGRAPHYThe features of the surface of the earth, including relief, vegetation and water.
TRANSPARENT COPYA copy such as a colour transparency or positive film which allows the passage of light, permitting a clear view of objects beyond.
ULTRAVIOLET RADIATIONElectromagnetic radiation of shorter wavelengths than visible radiation but longer than x-rays; in the wavelength interval between 10 and 4000 Angstroms (one Angstrom equals 10-10 of a metre).
VACUUM FRAMEA contact frame, the upper surface consisting of glass, from which air is extracted to ensure close contact between photographic materials during exposure.
VALUE (Colour)The sensation of relative darkness (low) or lightness (high) of a colour or tone compared to another or as measured in relation to a grey scale.
VIGNETTINGThe gradual fading of a colour.
XEROGRAPHYA copying process that utilizes a selenium surface and electrostatic focus to form an image.
ZENITHThe “point” in the sky directly above a given place.

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