Engineering structures undergo deformation due to various kinds of static and dynamic loads. Thus, monitoring of structure, specifically large structures such as high-rise building, bridges, dams etc., is essential to ensure its safe deformation behavior. With multifold rise of traffic, to provide safety and to prevent disaster, it has become necessary to detect uncharacteristic deflections and vibrations of bridges. The instruments which are often used for measurement of defl ection such as
strain gauge, accelerometer, tiltmeter, vision system, optometer, laser gauge meter etc are often cumbersome as well as costly in implementation. Moreover, they suffer from one defi ciency or the other. Hence, there is a need for a method which is simple, economic yet provides accurate and reliable measurement.

In Today’s world, with GPS, we can survey ellipsoidal heights (h) with 5-10 cm accuracy for geodetic control points on land and differential heights (?h) between well defi ned topographic features with relative accuracy of 1: 1Million or better. In few specific cases, this type of accuracy may require specially designed GPS surveys. In navigational mode, an instantaneous positional accuracy of about ± 5 m is easily possible. As these heights are the direct product of the GPS survey(s) and thus defi ned with respect to the ellipsoid, which is a time-invariant zero reference surface, they can be used without any reference to the geoid or Mean Sea Level (MSL). If we recall, in the classical surveys, e.g., triangulations and/or traverses, the vertical angles used to provide the “?h” and thus there will not be any need to convert them to orthometric heights.

The environment of a Municipal Information system has undergone a sea change over last few years. Couple of years back the requirements of information system was designed and projected primarily from the planners community. They were satisfi ed if the physical information was supplied on a scale of 1:5000/ 1:10,000.

The 7th Asia Pacific ITS Conference & Exhibition was …

13,000 users attend ESRI’s 25th Annual User Conference

With nearly 13,000 users attending from more than 135 …

July 2005

IGARSS 2005

25 – 29 July 2005 Seoul, Korea

reg@igarss05.org

http://www.igarss05.org

25th Annual ESRI International …

NoCoordinates is a new section, where readers questions …

IV MURALI KRISHNA Professor and Head, Centre for Spatial Information Technology, Jawaharlal Nehru Technological University, Hyderabad
iyyanki@icorg.org

Geodesy is science of the measurement and mapping of the earth’s surface. Satellite Geodesy in an orderly intensive manner started with the launch of the first artificial satellite SPUTNIK in October 1957. By the year 1964, many basic geodetic problems …

We were taken aback.
We were taken aback when we were told by none other than the Wireless Advisor to Government …

As the designers and builders of infrastructure; surveyors, engineers and construction contractors know well the benefits gained from a strong infrastructure. Whether transportation, utilities or communication systems, infrastructure constitutes a society’s basic structure, the foundation upon which the growth of a community, state or entire nation depends.