Additionally, GPS systems have problems functioning properly in heavily wooded areas. Although they have increased the speed of surveying, GPS systems are only horizontally accurate to 20mm and vertically accurate to about 30mm. That said, GPS systems are not always as accurate as the surveyor would wish. In a short period of time, total stations have gone from being mechanical/electronic devices to purely electronic systems with on-board computer and software.Īs Global Positioning Systems (GPS) have gained widespread use in the private sector, they have also predictably entered the arena of land surveying. More recently, modern electronics have improved on the theodolite with the addition of an electronic distance measurement device, or EDM these tools are referred to as total stations. More sophisticated versions of theodolites were still being used as late as the 1990’s for simple surveys, along with other equipment to improve the accuracy. However, because of the theodolite’s bulk, the surveyor’s compass was still used in heavily wooded areas, leading to its resurgence in popularity during the Colonial period in the United States. Because of the greater accuracy, the theodolite was the preferred tool for surveyors throughout Europe by the early 1800s. A theodolite could measure both horizontal and vertical angles. It was used to measure horizontal angles. The surveyor’s compass, or circumferentor, consisted of a brass circle and an index on the circle was a compass. Leaps and bounds in accuracy in surveying were made with the introduction of such equipment as the surveyor’s compass and theodolite. These chains would be pulled taut, and attempts were made to hold the measure level in order to improve accuracy. In its earliest forms, one of the main tools for conducting land surveys was a chain (sometimes known as a Gunter’s chain) of a specific length. We are at the dawn of a new era, however, and surveying technology that went virtually unchanged for hundreds of years is now being introduced to the computer age, which has served to only make our surveying estimations even more accurate than before. Many surveying tools in use today are similar to those that were employed to map and survey the initial settlements of the United States. While the use of such tools were all but lost in the Middle Ages, the Renaissance saw a resurgence in interest and need in tools to survey and parcel the land around them. The middle point of the second line is shown.Ĭlick several points to obtain a path and calculate its total length.Ĭlick several points to obtain an area (closed path) and calculate its surface area and perimeter.Ĭlick several points and find their common center assuming they form a circle.Ĭlick a point to define the circle, move the mouse to the center of the circle and click.Ĭlick 2 points to define the long axis of the ellipse and next click any 3rd point that lies on the ellipse.įinds the contour of objects automatically.Since ancient civilizations in Mesopotamia, Egypt and Rome, man has used tools to measure and keep his boundaries in order to separate himself from his neighbors. Next click a 3rd point to draw a second line perpendicular on the first line. Close the lock when you need to perform several measurements with the same tool.ĭraw line (click two points) to define the unit of measurement.ĭraw line to measure a length or distance.įirst click 2 points to draw a line. When the lock is Open, the program returns to Select mode after performing a measurement using any of the tools below. You can measure objects in the image using any of the following Measurement tools:Īllows to select existing measurement objects in the image.
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