- 行业: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
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 line segment joining two points of a circle and passing through the center of the circle.
Industry:Earth science
The distance from the point of intersection (vertex) of a curve to its point of tangency or point of curvature.
Industry:Earth science
(1) The failure of a lens system to reproduce accurately, in image space, the angle subtended by two points in object space. (2) Distortion, in a map projection, because of non conformality. (3) The change in shape of a small circle on a sphere when it is transformed to a plane by a projection.
Industry:Earth science
Displacement of images radially outward from the photograph nadir because of atmospheric refraction. It is assumed that the refraction is symmetrical about the nadir.
Industry:Earth science
The difference between absolute and apparent magnitudes of a celestial body. e.g., the Sun's distance modulus is - 31. 57 m.
Industry:Earth science
(1) The perpendicular distance from the internal perspective center of a projector to the plane, in the projector, of the photographic copy (finished negative or print). This distance is equal to the calibrated focal length of the camera that took the original photograph, corrected both for the enlargement or reduction ratio and for the shrinkage or expansion of the film or paper since the photo-graph was taken. It preserves the same perspective angles at the internal perspective center to points on the photographic copy as existed in the camera taking the picture at the moment of exposure. This is a geometrical property of each particular, finished negative or print. It is also called the effective focal length. (2) The perpendicular distance from the internal perspective center of the projector of a stereo-scopic plotter to the plane, in the projector, of that side of the diapositive on which the emulsion lies.
Industry:Earth science
The direction, at a point, of the downward pointing tangent to the vertical at that point.
Industry:Earth science
A method of determining the amount of tilt of an aerial photograph by comparing the displacements of image points for which the vertical and horizontal coordinates of the corresponding ground points are known.
Industry:Earth science
That correction applied to offset the effect, in a double projection, direct viewing stereoscopic plotter, of radial distortion introduced in an original negative by the objective lens of an aerial camera.
Industry:Earth science
