Journal of Surveying Engineering

Six electronic, digital theodolites of different capabilities are compared for accuracy in horizontal‐ and vertical‐angle measurement. Angles of known values are observed several times using each of the test instruments and root‐mean‐square error values of angle‐measurement were computed. The results show that the highest accuracy values are obtained with the Wild T2000. However, results obtained by the Wild T1000 and the Kern E1, with much less display‐resolution figures, were not very significantly different. Thus, the T1000 gave accuracy values of around $\pm {1.02}^{″}$ for horizontal‐angle measurement and $\pm {1.04}^{″}$ for vertical‐angle observations as compared to $\pm {0.64}^{″}$ and $\pm {0.63}^{″}\text{,}$ respectively, with the T2000. The corresponding figures for the Kern E1 are $\pm {0.90}^{″}$ and $\pm {0.92}^{″}\text{.}$

Current operational data‐base management system technology is restrictive in its capacity to clearly model and efficiently manage complex data objects, in general, and spatial data objects, such as those handled by geographic information system (GIS) software, in particular. This has led to the prevalence of hybrid GIS software architectures, in which the lexical and geometric components of spatial data are managed in a disintegrated fashion. However, recent developments in object‐oriented DBMS technology suggest approaches for the unified management of spatial data. The need for distributed management of spatial data poses further technological challenges. Structure transfer protocols must be further developed to support real‐time interchanges of subsets of spatial database on a query‐by‐query basis. Distributed crash recovery, concurrency control, and multiple copy updated capabilities as developed for distributed relational data bases must also be provided for distributed object‐oriented data bases. Also, the technology to support physical and semantic integration needs to be further developed to allow distributed GISs to be built from pre‐existing single‐site components.

A cheap, sensitive, compact tiltmeter made of melted silica is developed for the measurement of small movements of civil engineering structures. Available surveying instruments are expensive, moderately sensitive, and they rarely give continuous records. For these reasons, a new instrument was designed, derived from a high sensitivity tiltmeter used for the measurement of terrestial tidal waves. It is a horizontal pendulum, operating in a vacuum, realized with two silica fibers and a silver mass. A photoelectic cell is used for the detection of the mass movement. The range and resolution depend on the prechosen natural period of the pendulum, which can be adjusted by the operator. The instrument is tested in the laboratory and the field. Results obtained in a volcanic survey reveal that this type of instrument gives precise information about the behavior of a volcano before and after eruption: the direction and the speed of the interior magma, the future opening position, and its inflation and deflation.

Deformation measurements on large man‐made structures are important, especially in the first few years after construction is complete. In this paper, after a distinction is made between geometric deformation analysis and structural deformation analysis, the geometrical deformation analysis of the Olympic Speedskating Oval Roof structure is described. The geometrical deformation analysis was carried out using a computer program system developed in the Department of Surveying Engineering at the University of Calgary. The computer program system was applied to four epochs of survey measurements inside the Olympic Speedskating Oval in Calgary in order to determine the deformation behavior of the Olympic Oval roof during the period summer 1986 (completion of construction) to summer 1989. The deformations of the Olympic Oval roof during this period, which are due mainly to creep and shrinkage of the concrete in the roof beam columns, are in very close agreement with those predicted by the designers of the structure.