Increasing resolution and lower cost of off‐the‐shelf digital cameras are giving rise to their use in traditional and new photogrammetric activities such as aerial mapping, transportation and surveillance as well as archaeological, industrial and medical applications. For most, if not all, photogrammetric applications, the interior orientation parameters (IOP) of the camera need to be determined and analysed. The derivation of these parameters is usually achieved through a bundle adjustment with self‐calibration procedure. Prior to using a camera in photogrammetric applications, the IOP should be estimated and their stability should be checked. Camera stability has been rarely addressed when dealing with analogue metric cameras since they have been carefully designed and built to assure the utmost stability of their internal characteristics. However, the stability of low‐cost digital cameras needs to be investigated since these cameras are not built with photogrammetric applications in mind. This paper introduces three quantitative methods for testing camera stability, where the degree of similarity between reconstructed bundles from two sets of IOP is evaluated. Each of these methods limits the position and orientation of the bundles in a different way. Hence, each method is applicable for a specific georeferencing methodology depending on similar constraints imposed by the stability measures and different georeferencing techniques. The paper will test this hypothesis on the basis of reconstruction results obtained from the use of a low‐cost digital camera in an aerial mapping project.
The steady evolution of mapping technology is leading to an increasing availability of multi‐sensory geo‐spatial datasets, such as data acquired by single‐head frame cameras, multi‐head frame cameras, line cameras, and light detection and ranging systems, at a reasonable cost. The complementary nature of the data collected by these systems makes their integration to obtain a complete description of the object space. However, such integration is only possible after accurate co‐registration of the collected data to a common reference frame. The registration can be carried out reliably through a triangulation procedure which considers the characteristics of the involved data. This paper introduces algorithms for a multi‐primitive and multi‐sensory triangulation environment, which is geared towards taking advantage of the complementary characteristics of spatial data available from the above mentioned sensors. The triangulation procedure ensures the alignment of involved data to a common reference frame. The devised methodologies are tested and proven efficient through experiments using real multi‐sensory data.
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AASHTO guidelines for the geometric design of highways require that the insides of horizontal curves be clear of sight obstructions to provide required sight distance. However, the guideline's method for determining minimum roadside clearance is suitable only for middle sections of horizontal curves at sites where the circular arcs are equal to or longer than sight distance. For other sites and sections of horizontal curves, the guideline recommends the use of graphical or computational methods. The graphical method is tedious and time-consuming, and the recommended computational method was prepared for sites with circular arcs equal to or longer than sight distance. An analytical model was developed for clearance offsets for sites with circular arcs shorter than sight distance. Offsets were defined as normal ordinates from the driver path to a curve that demarcates the roadside area that accommodates sightlines. Variables in the model are sight distance, length of transition, length of circular curve, radius of circular curve, and driver location. Design charts for maximum and intermediate offsets were developed for use by practitioners with the model. Offsets from the charts for curves that have transition arcs were significantly shorter than offsets for equivalent simple curves. With these charts, the extra excavation costs associated with the resultant bigger offsets of other models can be avoided. Study results will be of value to engineers involved in design policy, highway maintenance, and design improvement for sites with insufficient sight distance.
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