GIS-DEFINITION OF TERMS

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.

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

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

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

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

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.

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

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.

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

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

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

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

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.

A monument point of known elevation.

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

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

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

(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.

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

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

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.

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.

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

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

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

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 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.

This control positions and identifies ground points by survey ties or plane coordinates.

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.

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

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.

In mapping, vegetation over a terrain.

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.

In mapping, man-made features.

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.

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

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

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

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.

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.

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.

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.

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).

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.

The average vertical distance between the aerial camera and the ground.

The flight path of the airplane carrying the camera.
The strip of photographs produced from a single flight.

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

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

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

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.