The conventional method for measuring tidal current velocity generally employs current meters suspended, at predetermined depth, from buoys located at limited number of selected locations. Recently in Japan, the high industrial development and rapid harbour construction have brought demands for more detailed and synoptic surveys of current in straits and harbours. The aerial photogrammetric measurement of tidal current, adopted by the Coast and Geodetic Survey, U. S. A., for the first time, have given us some useful hints for our own development in tidal current measurement, which in turn gives answer to the above mentioned demands. This paper reports the principles and methods of photogrammetric measurement of tidal current survey, and the new techniques such as synchronized photography and vector analysis, developed by the authers. In next paper (part II), the results obtained by these methods applicated to Akashi Seto (Akashi strait), Japan will be reported.

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Up to now a number of papers for geological interpretation on aerial photographs at various scales have been published.
This paper refers to the relation between photo scale and interpretation results based on two factors such as drainage and lineament.
The drainage density and frequency, and lineament direction and frequency are determined and compared to the geology or geological structure gained from the field survey.
Consequently, the variation of photo scale is not necessarily so disturbed the interpretation of drainage density and frequency, but we found some differences in the directions of lineament.
The lineaments interpreted from small scale photographs were well agreed to the geological structure of the area.

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All of Canada has been covered by aerial photograhs, except for a small area in Labrador. The aerial photographs at scales ranging from 1: 35, 000 to 1: 70, 000 are common for topographic mapping and photo interpretation.
The files of the National Air Photo Library contain close to 3 million vertical, trimetrogon and oblique photographs. The library keeps complete records of all survey photography done by and for the Federal Government. The library is very important for popularization and effective utilization of aerial photographs.
Canada is divided into 7 physiographic regions which are the Canadian Shield, the Appalachian Region, the Hudson Bay Lowland and the Arctic Archipelago, the Interior Lowlands, the Great Plains, and the Cordilleran Region.
Five aerial photographs of the Canadian Shield and the Great Plains are taken to show the physiography and land use.

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[in Japanese]

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[in Japanese]

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