A practical method of exterior orientation of a stereopair in two-medium photogrammetry is proposed. An important and difficult problem in two-medium photogrammetry is to reconstruct the space model of the photographed object by the projectors of stereoscopic plotting instruments. Even if the stereopair is projected in correct perspective position, the corresponding rays issuing from the photographs do not intersect. The corresponding rays intersect only after refracting at the interface of two media, similar to the object space.
The proposed method consists of two phases, relative and absolute orientation, in order to be able to utilize stereoscopic plotting instruments generally used. The residual y-parallaxes which should be appear in directly projected corresponding rays are computed at first. The relative orientation of the stereopair is, thereafter, carried outso as to leave these y-parallaxes. In this case, only five exterior orientation elements are used notwithstandding that eight elements are theoretically necessary to reconstruction of the model. The remaining seven exterior orientation elements are determined by absolute orientation. In this phase, one has to point out that the true position of control points can not be found directly by the plotting instruments. Therefore, an alternative method should be applied: The one is that imaginary apparent positions of given control points are computed and used for absolute orientation, and the another is that observed apparent positions are converted into the true positions by computation and these positions are compared with the given positions of the control points. The former is adopted in the present paper.
Successively approximate procedure is necessary in this method of orientation because both relative and absolute orientation are not correct from a theoretical point of view. Accuracy and characteristics of the proposed method are investigated by computation for typical examples. Denoting the Hight of camera from the submerged object by H and water depth by Hw, sufficient accuracy is obtained by only the first orientation within the limit of Hw/H<0.95. If the orientation procedure is repeated once more, fairly good result can also be obtained for the casees of greater Hw/H.

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This paper describes analytical block aerial triangulation system developed by our firm. We are confident of high practicability on our systems.
We defined practicabilities as follows;
1) All of operations concerning aerial triangulation are to be symplified, automatically worked and moreover each system function is to be worked systematically.
2) Whole system should be superior to non-block method as to economy and accuracy.
3) Computer size to be used should be selected considering payability.
Aiming to meet with practicabilities above, the key procedure described here is to solve by least square method simultaneously two conditional equations; one to determine absolute condition using control points included in a block and another to determine relative condition between course using tie points, in the stage of conversion from strip coordinates in aerial triangulation to geodetic coordinates. Instrumentations used are Zeiss Stereocomparator and Japanese made computer “TOSBAC-3400”.

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The procedure of simultaneous adjustment of photographs has been developed utilizing a method of least squares at the object points. An attempt has been made to develop a new set of condition equations defining the relation between each object point and its corresponding rays from exposure station positions. The mathematical formulations based on the set of condition equations have led to a feasible computational procedure. In particular the structure of the coefficient matrix of normal equations has been examined carefully, in order to conserve the limited computer storage capacity and also for the purpose of saving execution time in the computer. Reduction of the coefficient matrix of the normal equation system to a favorable bandwise structure has been performed by changing the order of obseevation equations which are used form the normal equations.
The procedure has been coded in FORTRAN IV and computed on an IBM 360/50 computer at the Comuter Center in the University of New South Wales.
The procedure has been tested using simulated data of near vertical photography, prepared by the Autometric Corporation of the Raytheon Company, for the U.S. Army Engineering Topographic Laboratories. Fictitious blocks of five strips of five photographs and three strips of ten true coordinates of the image points and the object points.
This projecc was accomplished as the thesis of Master of Surveying in the University of New South Wales, Australia.

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Since 1963, block adjustment has been employed regularly at Asia Air Survey Company. The main reason is that block adjustments can be effectively applied to aerial triangulation; i.e., many blocks may be adjusted covering a comparatively large area-an actual example being the compilation of base maps for forestry.
At the present time, these adjustments together with bi-altitude triangulation are frequently used in our company. Details of block adjustments, with numerical examples, are introduced in this paper.

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A method of block adjustment developed by Toyo Jigyo Co., Ltd. is reported. The system of block adjustment is treated as a sub-system of whole system what is called Toyo-Koku-Operating System. The system gives satisfactory results.

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