Section 9

GLOSSARY


 

 

 

Acceptance:  The formal written acceptance by the Commissioner of Transportation of an entire Contract which has been completed in all respects in accordance with the Contract documents.

Accuracy:  The degree of agreement between a measured value and the true value.

Aerial Negative:  The original photo image produced by aerial photography onto reproducible film and used to produce prints and/or positive photographs.

Aerial Photograph, Oblique:  Photographs taken at any angle below the horizon short of ninety degrees and used primarily for environmental analyses and outside presentations.

Aerial Photograph, Vertical:  An aerial photograph with the camera’s longitudinal axis as close to truly vertical (90° below horizontal plane) as possible.

Aerotriangulation:  The establishment of supplemental control points by precisely marking their locations onto glass photographic diapositives.  Spatial solutions are then obtained by precise measurements and computational routines.

Air Base:  The line, or length of line, joining two adjacent camera stations.

Altitude:  The vertical distance above the reference elevation or datum, usually the National Geodetic Vertical Datum of 1929, or the North American Vertical Datum of 1988, of an object or point in space.

Analytics:  The densification of horizontal and vertical control using measurements made on aerial photographs through aerotriangulation methods.

Antivignetting Filter:  A filter used with wide-angle photography to produce uniform lighting over the whole photograph.

Attitude:  The angular orientation of a camera with respect to some external reference system.

Azimuth Line:  A radial line from the Principal Point of a photograph to a similar point in an adjacent photograph in the same flight line.

Basic Control:  A system of horizontally and/or vertically established and monumented control points over the entire roadway project.  Such points are established at a one to two kilometer spacing to serve as closure points for all other project surveys.

Bench Mark:  A monument point of known elevation.

Cadastral:  Pertaining to the extent, value and ownership of land.  Cadastral maps show property corners and property lines.

Camera Axis:  A line through the camera’s rear nodal point which is perpendicular to the film plane.

Camera Station:  The point in space where the forward node of the camera lens was located at the instant the exposure was made.

C-factor:  (also called Contouring Factor)  The ratio of the flight height to the smallest contour interval which a photogrammetric system can consistently compile on a map manuscript to the required accuracy.

Comparator:  A precise instrument which measures two dimensional plane coordinates from a vertical aerial photograph.

Compilation:  The production of a map or base plan from aerial photographs and geodetic control data using photogrammetric instruments and techniques.

Contact:  A method of printing in which an original translucent photograph or drawing is placed in contact with photosensitive material and exposed, thereby producing an exact image of the original onto the material.

Contract:  The legally binding agreement between the NJDOT and the Contractor setting forth the obligations of the parties thereunder, including but not limited to, the performance of the work, the furnishing of labor and materials, and the basis of payment.  The Contract represents the entire and integrated agreement between the parties and supersedes all prior negotiations, representations or agreements, either written or oral.

Contractor:  The individual, partnership, firm, corporation, or any acceptable combination thereof, contracting with the NJDOT for performance of prescribed work.

Contour:  A theoretical line tangent to the earth’s surface at a known elevation.  Also, a line “locating” this elevation on a map or plan.

Contrast:  The degree of difference between the lightest and darkest areas of a photograph.

Control:  A system of horizontally and/or vertically established monumented points used to reference map features.  There are four classifications of precision (the first order being the highest) depending upon the overall precision and quality of the methods and instruments utilized.

Control, Ground:  Control brought about by conventional field survey methods as opposed to aerial survey methods.  This control is used to complement photogrammetry work and to compensate for any deficiencies resulting from the latter.

Control, Horizontal Ground:  This control positions and identifies ground points by survey ties or plane coordinates.

Control, Vertical Ground:  This control positions points vertically relative to a reference datum such as the National Geodetic Vertical Datum of 1929 or the North American Vertical Datum of 1988.

Control Point:  On a photograph, any identified station or reference point used in fixing the attitudes and/or positions of one or more related photographs.

Coordinates:  A set of “cell” numbers or “addresses” used to define the positions of points on a photograph or plan sheet with respect to a reference grid system.  In photogrammetry, the coordinate axes are usually either the fiducial axes, or the principal line and the photograph parallel.  If a three dimensional system is used, the origin is either the principal point or the perspective center.

Cover:  In mapping, vegetation over a terrain.

Crab:  The condition caused by failure to correctly position the camera with respect to the airplane’s line of flight.  This results in the angular displacement of the photographic axis relative to the flight line.

Culture:  In mapping, man-made features.

Deformation:  A change in the position of a point on a photograph, map, manuscript or print from its originally plotted position.  This change is the result of differential shrinkage and/or expansion of the film or paper.

Develop:  To process exposed photographic material and thereby reveal the latent image contained thereon.

Diapositive:  A positive photographic transparency, usually glass, designed for use in a precision photogrammetric instrument.

Displacement:  Any shift in the position of a point, line or feature on a photograph.

Displacement Due to Relief:  An unavoidable characteristic of aerial photography in which high and low elevation points appear further from and closer to the center of aerial photographs, respectively, than their actual positions indicate.

Distortion:  A change in the position of a point on a photograph from its original position caused by an aberration or combination of aberrations in the camera lens.

Dodging:  The selective shading or masking of a portion of a photograph during copying to soften the contrast.  Automatic dodging selectively varies the illumination over the photograph in proportion to the average density of each area on the photograph.

Electronic Distance Measuring Instrument or Device (EDMI):  An instrument which transmits and receives a modulated electromagnetic signal and translates the raw data into a readout of distance between the instrument and the reflector or retransmitter.  The readout is automatically derived from the monitoring and compiling of phase differences between the modulations of transmitted and reflected or retransmitted signals.

Elevation:  Is the vertical distance above or below an arbitrarily assumed level surface of curved surface every element of which is normal to the plumb line.  The level surface used for reference is called datum.  The datum in this case is the North American Vertical Datum of 1988 (NAVD 88).

Fiducial Marks:  Indicators produced in the middle of each border and/or in each corner of the negative at the moment of exposure and used to locate the photograph’s principal point.

Flight Altitude:  The average vertical distance between the aerial camera and the ground.

Flight Line or Flight Strip:  (1)  The flight path of the airplane carrying the camera.  (2)  The strip of photographs produced from a single flight.

Flight Plan:  The aerial photography operational procedure in which the flight objectives and the performance criteria are specified.

Focal Length:  The distance from the plane of infinite focus to the center of the camera lens.

Geodetic Survey:  A survey which takes into account the curvature of the earth’s surface.

Geoid:  An equipotential surface (a surface of equal gravity) coincident with the National Geodetic Vertical Datum of 1929 or the North American Vertical Datum of 1988.

Grid:  A uniform system of equally spaced perpendicular and parallel lines superimposed onto aerial photographs, mosaics, maps, plan sheets and other representations of the earth’s surface and used to identify the positions of points.

Inertial Surveying:  A system that used accelerometers, gyroscopes and a computer to sense the earth’s rotation and to orient itself with respect to north-south and east-west alignments as well as to the direction of gravity as it is moved from point to point.

Interpretation:  The result of a stereoscopic examination of aerial photographs, augmented by data and imagery from other sources, to obtain qualitative information about the terrain, cover and culture which may influence the location of a proposed highway.

Manuscript or Base Map:  The original master reproducible sheet upon which the data gathered from the aerial photographs has been compiled.

Map, Index:  (1)  A small-scale map showing the position and orientation of each map or contract plan sheet with respect to all the other map or contract plan sheets in a given project.  (2)  A map showing the locations and numbers of flight strips and photographs.  (3)  A small-scale map showing geodetic control and such data comparable to that found on larger-scale topographic quadrangle maps.

Map, Photogrammetric:  An orthographically projected rendering of existing land features produced with a stereoplotting instrument.

Map, Planimetric:  A reproducible copy of the manuscript showing the shape and horizontal position of natural and man-made (cultural) features with no regard for elevation or measurable relief.

Map, Topographic:  A reproducible copy of the manuscript showing the shape and the horizontal and vertical position of natural and man-made features.  Elevations and measurable ground relief are usually delineated by contours and by spot elevations at prominent locations.

Micron:  (also known as Micrometer).  A unit of length equal to one thousandth of a millimeter (0.001 MM).

Model:  The stereoscopic image of an area produced by viewing the end lapping of two successive aerial photographs depicting the same ground area from two different positions of exposure and culminating in a three dimensional image when observed through a binocular viewer.

Mosaic:  A large sequential composite of individual photographs showing a continuous overview of a project site from beginning to end.

Mosaic, Controlled:  Wherein each photograph was sealed and rectified relative to horizontal ground control and matched to adjacent photographs as closely as possible.

National Geodetic Vertical Datum of 1929:  The average of the heights of the sea surface at all stages of tide.  In photogrammetry, the National Geodetic Vertical Datum of 1929 is also referred to as Mean Sea Level.

Nadir Point:  (1) Photographic:  where a vertical line originating from the central point of exposure in the camera intersects the plan of the photograph.  The photographic nadir point coincides with the principal point of the photograph when that photograph is truly vertical.  (2)  Ground:  where that vertical line intersects the ground surface.  (3) Datum:  where that vertical line intersects the reference datum surface.

Neat Model:  The stereoscopic area between adjacent principal points along the flight line (breadth) and extending out sideways to the middle of the side laps (width).  The neat model represents the approximate mapping area of each pair of overlapping aerial photographs, (width) x (breadth).

NJDOT:  State of New Jersey, Department of Transportation.

North American Vertical Datum of 1988:  A datum formed by using an ellipsoidal approximation of the planet surface, recalculated in 1988.

Nodal Points:  A camera lens has two such points:  an incidental (frontal) point and an emergent (rear) point.  These points lie on the optical axis of the lens and have the property that any light ray directed toward the incident point passes through the emergent point and emerges on the other side of the lens in a direction parallel to the direction of the incident ray.

Oblique Photograph:  A photograph taken with the axis of the camera intentionally directed so that it is neither vertical nor horizontal.

Orthographic:  Characterized by perpendicular lines or right angles.

Orthophotograph:  A photographic reproduction in which each image has been extrapolated into its map-oriented (orthographic project) position.

Overlap:  The amount by which two adjacent photographs show the same area.  This amount is usually expressed as a percentage of the total linear dimension of the photograph in the direction of the overlapping.

In aerial photographs, the overlap within the flight line is called the end lap, and the overlap in adjacent parallel flight lines is called the side lap.

Panels:  Ground control points which are readily identifiable in aerial photographs.  Also referred to as Targets.

Parallax:  (1)  An apparent change in position of one object relative to another when viewed from different positions.  (2)  The change in position of an image from one aerial photograph to the next as a result of the aircraft’s motion.

Photogrammetry:  The science of obtaining accurate measurements through the use of aerial photographs and stereoplotting equipment.

Photographic Index:  A mosaic of individual adjacent photographs in their proper relative positions and re-photographed at a reduced scale with accompanying designations.

Plane Coordinate System:  A horizontal reference system consisting of equally spaced perpendicular and parallel grid lines used to locate and establish the horizontal position of any point.  Such positions are established relative to the point of origin and principal axes of this system.  The two primary systems employed in New Jersey are the National Geodetic Survey and the New Jersey State Plane Coordinate System (NJSPCS (1927)/NJSPCS (1988), and generally all first and second order accuracy traverses and triangulation stations should be tied into one of these systems unless the NJDOT approves otherwise.

Planimetry:  The configuration of a surface and the horizontal positions of its natural and cultural features, depicted by means of lines, symbols and notations on a scaled map or plan sheet without regard to relief.

Plans:  The approved plans, profiles, typical sections, cross sections, shop drawings and supplemental drawings or exact reproductions thereof, which show the location, extent, layout and dimensions as well as the scope, character, and details of the work to be done.

Precision:  The degree of refinement with which an operation is performed.

Principal Point:  (1)  The intersection of two lines drawn through pairs of opposite fiducial marks on an aerial photograph.  (2)  The theoretical intersection of the camera’s line of sight axis, directed as vertically as possible, with the ground.

Print:  A photographically produced copy of a transparency.  Also called a contact print.

Print, Check:  A blue or black line copy of an original transparency used as a working copy to check the accuracy of the transparency and to perform related engineering work thereon.

Print, Contact:  A print made with a transparency in contact with a sensitized surface.

Print, Cronapaque:  A mylar-type, emulsion-coated material with a very low coefficient of expansion and extreme durability upon which a contact print may be produced.

Print, Paper:  An emulsion-coated, high grade paper used for the same purposes as the Cronapaque print, but available in single or double weights and in gloss, semi-matte or matte, and in resin-coated finishes.

Print, Ratio:  A print on which the scale has been changed from that of the original transparency by project printing.

Project:  The specific section of highway or public improvement together with all appurtenances and construction to be performed thereon under the Contract.

Proposal:  The offer of a bidder, properly signed and guaranteed, on the prepared from furnished by the NJDOT, to perform the work and to furnish the labor and materials at the prices quoted.

Rectification:  The production of a truly vertical photographic print from a tilted aerial negative.

Scale:  The ratio of a distance on an aerial photograph, map or plan sheet to its actual counterpart on the ground.  Scale may be expressed as a ratio (1:24 000), a representative fraction (1/24 000), or an equivalence (1cm = 24 000cm).  The photographic scale is generally taken as “f/h” where “f” is the principal distance of the camera and “h” is the height of the camera above mean ground elevation in metric.

Scribing:  A method of drafting which removes a pigment from a coated mylar as a result of tracing a line thereon.  Transparent lines are thus produced on the mylar from which, upon completion, prints can be readily made.

Specifications:  The state of New Jersey Department of Transportation, Aerial Photogrammetric Specifications of October 1995, including latest revisions.

Spot Elevations:  Reported elevations of high, low and other prominent points.  The precise location is generally denoted by a small “x” and is thereby accompanied by the reported value of the elevation.

Stereocomparator:  A comparator used in stereoscopically measuring images on adjacent aerial photographs.

Stereoplotter:  An instrument designed to produce stereoscopic images or models from which very precise topographic maps can be compiled by utilizing electromechanical components of the instrument.

Stereoscopy:  The science of producing three dimensional images by viewing the overlap area of two photographs through a binocular viewer.  The overlapping photographs are produced with the camera at a slightly different location or perspective of one exposure relative to the other.

Stereotriangulation:  Triangulation is a procedure dealing with locating and establishing a position by means of bearings from two fixed points a known distance apart.  The application of this procedure in photogrammetry utilizes a stereoscopic plotting instrument to obtain successive orientations of adjacent photographs into a continuous strip.  The spatial solution for the extension of horizontal and vertical control using strip coordinates may be made by either graphical or computational procedures.  Also referred to as Aerial Analytical Triangulation.

Supplemental Control:  One or more surveys between basic or primary control points to establish any additional points needed to complete the required mapping.

Target:  A symmetrical pattern in high contrast to the background against which it is placed, it is used in locating and working with a specific control point from an aircraft and especially with its corresponding image in an aerial photograph.

Tilt:  The departure of the camera’s line of sight from vertical.

Topography:  The configuration of a surface including its relief (usually represented by contours and spot elevations) and the positions of its natural and cultural features as shown on a map or plan.

Total Station:  A vertical and horizontal angle-measuring instrument with an electronic distance-measuring device either attached to or integral with the telescope and containing decoders which convert angle measurements to digital form.  Such instruments make data immediately available on slope, horizontal distances and differences in elevations.  They may also compute horizontal coordinates and elevations.  Some are equipped to record all data on computer-compatible data storage media.