摘要
A geo-reference is a global or regional geographical or geodetic coor-dinate system to which sensors or spatial object data are related.Hence,geo-ref-erencing is close to the well known photogrammetric concept of exterior or abso-lute orientation,the common execution of which is indirect,via the use of groundcontrol point.GPS and INS technologies have changed the situation,permittingdirect measurement of position and attitude parameters and making exterior orien-tation feasible without ground control at all,in principle.The analysis of accuracyand reliability performance discloses,however,that especially INS does not yetmeet the high demands of photogrammetry.Moreover,control of systematic er-rors,the problem of datum transformation,and reliability conditions make theuse of some ground control points still mandatory,at least for any high perfor-mance geo-referencing.
A geo-reference is a global or regional geographical or geodetic coordinate system to which sensors or spatial object data are related. Hence, geo-referencing is close to the well known photogrammetric concept of exterior or absolute orientation, the common execution of which is indirect, via the use of ground control points. GPS and INS technologies have changed the situation, permitting direct measurement of position and attitude parameters and making exterior orientation feasible without ground control at all, in principle. The analysis of accuracy and reliability performance discloses, however, that especially INS does not yet meet the high demands of photogrammetry. Moreover, control of systematic errors, the problem of datum transformation, and reliability conditions make the use of some ground control points still mandatory, at least for any high performance geo-referencing.
