Introducing the Sighted to Maps for the Blind: A Report on the I.G.U. Tactual Map Exhibit

Tactual maps can be useful aids for blind mobility. Sighted visitors to an exhibit on maps for the blind at the August 1972 International Geographical Congress had an opportunity to try out tactual mobility maps for themselves. Blindfolded participants attempted to guide themselves through a maze with the help of such a map. Over half of those observed had some difficulty in finding their way. Evaluation of their performances suggests that unfamiliarity with methods for reading and using tactual maps was a major problem. The maze and tactual map exhibit also emphasized that tactual maps differ from visual maps in content, design, and reproduction. Special requirements in all these areas will have to be met before tactual mapping can fulfill its promise as a mobility tool for the blind.     

Comparison of the Graf sea gravimeter with the Vening Meinesz apparatus on board the submarineU.S.S. Becuna

Measurements of gravity were made on boardU.S.S. Becuna (SS 319) with a Vening Meinesz pendulum apparatus and a Graf sea gravimeter at approximately the same time. Comparison of data uncorrected for depth of submergence, E?tvos correction and second order effects of horizontal acceleration showed that there was a change related to time of observation. These corrections were not made as they would be the same for both sets of observations, and no provision had yet been made to take care of the horizontal accelerations for the Graf sea gravimeter. The variation with otime could be caused by instrumental drift or scale calibration. After removal of this effect by visually fitting the data trend with a straight line, there were three observations with large discrepancies, seventeen with discrepancies of 3–9 mgal and thirty-nine with discrepancies of 0–3 mgal, showing close approach to a statistical distribution. The three large discrepancies may be dismissed because of very bad depth control during the observations. The discrepancies 3–9 mgals are larger than expected and perhaps are attributable to depth control and inadequate observation time for the Graf sea gravimeter. It is concluded that the Graf sea gravimeter shows great promise for use on a submarine. An apparatus to take into account the horizontal acceleration effects must be added, and suitable drift characteristic obtained. Despite its advantages of ruggedness, ease of operation, ease of data reduction, reduced size and weight, many more comparisons of the Graf sea gravimeter with the Vening Meinesz pendulum equipment should be made before the latter are displaced Probably the Graf sea gravimeter will be usable on a stable platform on a surface vessel at least in calm sea states.     

中美卫星导航领域的合作框架分析

本文研究目的是探讨中国与美国在开展卫星导航方面(北斗系统与GPS系统)合作时的整体框架、合作内容, 从而为我方制定可用的立场与策略。相关建议仅供参考。      

Towards the Automated Map Factory: Early Automation at the U.S. Geological Survey

This paper is concerned with changes in map work at the U.S Geological Survey during the period from 1950 to 1974. At the start of this period, mapmaking at USGS was dominated by manual techniques organized to conform to twentieth-century advances in photogrammetry, drafting techniques, materials, and industrial organization. During the 1950s and 1960s, technologies that had been developed in other sectors of American science and industry were inserted into mapping processes with hopes of huge productivity gains and added efficiencies. The development paths of two in-house devices, Autoplot and Autoline, illustrate the ways in which cartographic automation became an agency policy as well as a powerful ideology.     

A Cadastral Geodatabase for the U.S. Fish and Wildlife Service

The U.S. Fish & Wildlife Service Cadastral Data Working Group, comprised of cartographers and GIS specialists from all management regions, has produced a state-of-the-art database that stores data for all interests in real property in the U.S. National Wildlife Refuge System. The FWS Cadastral Geodatabase provides an integral component of the Refuge Lands Geographic Information System (RLGIS) by supplying boundary and parcel information to the biological geodatabases currently within the RLGIS data model. Cadastral data describes the past, current, and future right, title and interest in real property, including the spatial information necessary to describe the geographic extent. The geodatabase is the common data storage format for geographic features and attributes. A consistent and accurate cadastral geodatabase that is common across the nation and can be shared between management regions enables users to leverage the spatial data to its full potential. A web mapping application has been built utilizing the FWS cadastral geodatabase, allowing a non-GIS user to view the FWS managed lands and waters.