Around the early 19th century when the country scale survey of INOH, Tadataka was carried out, some country scale surveys were performed. Those are the map of Japan in Kyouhou era (Kyouhou Nihonzu) compiled by TAKEBE, Katahiro in response to a command of the Shogun Yoshimune, the cadastral survey in Ryukyu (Kenryu Kenchi) and its compiled map of “Ryukyu-Kokunozu”, and the “Rapid Surveyed Map” (Jinsoku-Sokuzu) in Meiji era.
In order to evaluate the Inoh's survey I compared it with these surveys so that I would point out the following results.
(1) In the Kyouhou Nihonzu and the Kenryu Kenchi, the idea of survey and map compilation by using ground control points is recognized. The accuracy of map compilation is secured by using direction targets (Miate-yama) in the case of the Kyouhou Nihonzu or triangulation points (Shirubiishi) in the case of the Kenryu Kenchi. On the other hand, surveyed lines are the framework of map in the case of Inoh's map and the Inoh's survey does not have the idea of ground control point.
(2) In the Kenryu Kenchi, the triangulation system was seemed to be built and the replication of survey was secured by constructing the Shirubiishi network.
(3) It may be said that a portent of the modernity to develop to the concept of ground control point is recognized in the Kyouhou Nihonzu and the Kenryu Kenchi. The Inoh's survey performed astronomical observation and intended to get the data of longitude and latitude. It may be said a portent of the modernity. The Kyouhou Nihonzu and Kenryu Kenchi did not have the concept of the longitude and latitude.
(4) The Inoh's survey shows the peak of the survey in the early modern times, but it may be said that there was technological thought exceeding the Inoh's survey in the Kyouhou Nihonzu and Kenryu Kenchi.
(5) If it is called for modern survey to perform triangulation and leveling based on the ground control points, the Jinsoku-Sokuzu in Meiji era should be origin of modern survey to be performed systematically.
Concerning INOH, Tadataka, there are many studies about his life and person image, process of his survey trip, origin or whereabouts of the Inoh's map and so on. But there are few studies about his technology of survey and map compilation. Therefore, there are many questions about his survey technology. I will hope that study on survey technology of INOH, Tadataka will advance in near future.
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