- Industri: Earth science
- Number of terms: 93452
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Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
A condition placed on the constants defining a coordinate system and resulting in the smallest sum of the elements along the main diagonal in the inverse matrix of a set of normal equations.
Industry:Earth science
The azimuth or bearing of a line along which a ship or aircraft is to travel or does travel for a specified period of time. This definition is also given as the azimuth or bearing of a line along which a ship or aircraft is to travel or does travel, without change of direction, or as the direction of intended motion of a craft in the horizontal plane, measured relative to the water in the instance of a watercraft but relative to the earth in all other craft. It is also given as the direction a navigator wants his craft to travel for a given period of time, or hopes his craft has followed. The direction of a course (d) is always measured in degrees from the astronomic meridian, and that direction is always meant unless it is otherwise qualified as, e.g., a magnetic or compass course.
Industry:Earth science
A contour inside of which the ground is at a lower elevation than the ground outside.
Industry:Earth science
(1) A description, recognized by law, which definitely locates property by reference to governmental surveys, coordinate systems or recorded maps. (2) The same as definition (1) but leaving out the word definitely. (3) A description which is sufficient to locate the property without oral testimony.
Industry:Earth science
Adjustment of the ellipsoid of reference of a particular datum so that the sum of the squares of the deflections of the vertical at selected points throughout the geodetic network is minimized.
Industry:Earth science
A diagram simulating the third dimension, in which the scale is correct along three axes. i.e., a diagram drawn so that the object represented appears to have three dimensions. The diagram is usually drawn by first putting in the three axes of a coordinate system, with suitable angles (such as 120<sup>o</sup> between each) between the axes. The x - and y-coordinates of points on the object are then plotted as usual on two of the axes; the z-coordinates of visible points are plotted using the third axis.
Industry:Earth science
The part of a camera wherein data can be recorded on the margin of the film or plate. Data placed on photographs taken for mapping usually include the time of exposure, altitude, frame number and identification number. They are usually recorded automatically.
Industry:Earth science
A corner of the public land surveys whose location can not be verified by the criteria necessary to class it as a found or existent corner, but which is accepted locally as the correct corner and whose location is perpetuated by such marks as intersections of fence lines, piles of rock, or stakes or pipes driven into the ground which have been recovered by investigation in the field.
Industry:Earth science
(1) An equipotential surface passing through a specified point whose elevation above mean sea level is known and which is used as a referent for elevations. (2) A surface passing through mean sea level at certain specified points and through other specified points whose elevations are known, and to which vertical distances determined by leveling are referred. Because these points do not lie on a single equipotential surface, the surface they and the leveling are used to define is neither an equipotential surface nor a simple geometrical surface. A datum of this kind was defined by the U. S. C. & G. S. in 1929 and called Sea Level Datum of 1929. The name, but not the definition, was changed in 1976 to National Geodetic Vertical Datum. (3) Mean sea level used as a datum for elevations or depths. This datum is not valid for points on land, since sea level cannot be extended very far inward from the shore.
Industry:Earth science
