Method for determining the interior shape of spherical tanks for the computation of the liquid volume of the tanks, and device for carrying out the method

Abstract

Abstract For determining the interior shape of spherical tanks for the computation of the liquid volume of the same, the following steps are performed: An arbitrary system of coordinates is established based on field measurements in the tank of a given number of station points within the sphere. From the station points a plurality of reference points in the form of markers affixed to the inner surface of the sphere are identified with reference to said system of coordinates. In the field all the reference points and the inner surface of the sphere are photographed with double coverage for later representation of stereoscopic models in a photogrammetric autograph. All reference points are later plotted on a drawing sheet in a coordinatograph to establish a horizontal great circle plane of the sphere together with a first interim center of the sphere. A second interim center of the sphere is computed on the basis of said measured reference points and also this computed second interim center is plotted onto the drawing sheet in the coordinatograph. In the autograph stereoscopic models are made using the double coverage photographs and the drawing sheet with the plotted reference points are placed on a drawing table of a coordinatograph associated with the autograph, and both the reference points and further points on the surface of the sphere are read off in the autograph. The readings of said further points are guided along horizontal small circles which have been drawn on the drawing sheet and the actual readings are taken where said small circles are intersected by vertical planes which have been drawn through said second interim center of the great circle. All the coordinate values of the point readings are transferred to an interface unit. In the interface unit, which is connected on line with a computer assembly, the point coordinates are registered and converted into field coordinates, and the registered data in the interface unit are processed in the computer which on the basis of said read reference points and further points calculate the final mean radius of the sphere and lists out the deviation therefrom for every point of reading. The computer on the basis of said read points also calculate the mean radius of said horizontal small circles for calculating the volume of each of the areas between adjacent small circles to determine the total volume of said tank. The transfer of coordinate values read in the photogrammetric autograph may take place with a push-button or pedal controlled by an operator, or the reading or transfer of the coordinates to the interface unit may take place at given moments or when the autograph has covered a certain distance along one or more of the coordinate axes thereof.

Inventors

• 👤 Ole H. Blom
• 👤 Rolf Bakken

Bibliographic Details