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Temporary Adjustments Of Theodolites
Temporary adjustments are a set of operations which are performed on a theodolite to make it ready for taking observations. These include its initial setting up on a tripod or other stand, centering, levelling up and focusing of eyepiece. Initial setting The initial setting operation includes fixing the theodolite on a tripod, along with approximate levelling and centering over the station mark. For setting up the instrument, the tripod is placed over the station with its legs widely spread so that the centre of the tripod head lies above the station point and its head approximately level (by eye estimation). The instrument is then fixed with the tripod by screwing through the trivet. The height of the instrument should be such that observer can see through telescope conveniently. After this, a plumb bob is suspended from the bottom of the instrument and it should approximately align with the station mark. Centering A tribrach with an optical plummet (the black cylinder pointing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodolite
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and infrastructure construction, and some specialized applications such as meteorology and rocket launching. It consists of a moveable telescope mounted so it can rotate around horizontal and vertical axes and provide angular readouts. These indicate the orientation of the telescope, and are used to relate the first point sighted through the telescope to subsequent sightings of other points from the same theodolite position. These angles can be measured with accuracies down to microradians or seconds of arc. From these readings a plan can be drawn, or objects can be positioned in accordance with an existing plan. The modern theodolite has evolved into what is known as a total station where angles and distances are measured electronically, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodolite In Use
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and infrastructure construction, and some specialized applications such as meteorology and rocket launching. It consists of a moveable telescope mounted so it can rotate around horizontal and vertical axes and provide angular readouts. These indicate the orientation of the telescope, and are used to relate the first point sighted through the telescope to subsequent sightings of other points from the same theodolite position. These angles can be measured with accuracies down to microradians or seconds of arc. From these readings a plan can be drawn, or objects can be positioned in accordance with an existing plan. The modern theodolite has evolved into what is known as a total station where angles and distances are measured electronically, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surveying
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designed positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales. Surveyors work with elements of geodesy, geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages, and the law. They use equipment, such as total stations, robotic total stations, theodolites, GNSS receivers, retroreflectors, 3D scanners, LiDAR sensors, radios, inclinometer, handheld tablets, optical and digital levels, subsurface locators, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Attraction
While compass surveying, the magnetic needle is sometimes disturbed from its normal position under the influence of external attractive forces. Such a disturbing influence is called as ''local attraction''. The external forces are produced by sources of local attraction which may be current carrying wire (magnetic materials) or metal objects. The term is also used to denote amount of deviation of the needle from its normal position. It mostly causes errors in observations while surveying and thus suitable methods are employed to neglect these errors."Compass Surveying" by C. L. Kocher, Principal of Mehar Chand Polytechnic College, Jalandhar City, Punjab Sources The sources of local attraction may be natural or artificial. Natural sources include iron ores or magnetic rocks while as artificial sources consist of steel structures, iron pipes, current carrying conductors. The iron made surveying instruments such as metric chains, ranging rods and arrows should also be kept at a safe di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Survey Camp
Survey Camp is an army tradition that was discontinued in the later part of twentieth century but was reinstated in 2002 across the universities of the world with a whole new structure. It is the civil engineering training course for two weeks usually after completion four semesters of bachelor of technology that consists of 8 days working in the field and 6 days of map preparation in the computer lab. Experts say that survey camp provides necessary foundation for civil engineers. Each day in the course there are at least 8 hours of working in the field. Students are divided into groups and they get out with practising surveyors and use their equipment out in the field. A camp incharge teacher appoints group leaders for each group; the leaders are responsible for all the works of his particular group and the equipment. In the computer lab, students learn applications such as AutoCAD and Carlson Survey. The students use these programs to take data collected from the field to develo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ranging Rod
A ranging rod (or range rod) is a surveying instrument used for marking the position of stations, and for sightings of those stations, as well as for ranging straight lines. Initially these were made of light, thin and straight bamboo, or of well seasoned wood such as teak, pine or deodar. They were shod with iron at the bottom and surmounted with a flag about 250 mm square in size. Nowadays they are made of wood, metal or fibreglass. The rods are usually about 30 mm in diameter and 2 m or 3 m long, painted with alternating bands, such as red and white, red and yellow, or black and white, in lengths of 200 mm (i.e. one link length of metric chain), 500 mm, or one foot. These colours are used so that the rod can be properly sighted in case of long distance or bad weather. Ranging rods of greater length, e.g. 3 to 6 m, are called ranging or range poles, and are used for very long survey lines. Another type of ranging rod is known as an offset rod, which has no flag at the top. It is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tape (surveying)
A tape measure or measuring tape is a flexible ruler used to measure length or distance. It consists of a ribbon of cloth, plastic, fibre glass, or metal strip with linear measurement markings. It is a common measuring tool. Its design allows for a measure of great length to be easily carried in pocket or toolkit and permits one to measure around curves or corners. Today it is ubiquitous, even appearing in miniature form as a keychain fob, or novelty item. Surveyors use tape measures in lengths of over 100 m. Types There are two basic types of tape measures with cases: spring return pocket tape measures and long tape measures. Spring return pocket tape measures will generally fit in a pocket. They are small; the case is up to about three inches across. The tape is returned to the case by a spring mechanism. Pocket tape measures have a tape in length and across. A second tape measure design is what is called the long tape. These are cased tape measures with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permanent Adjustments Of Theodolite
The permanent adjustments of theodolites are made to establish fixed relationship between the instrument's fundamental lines. The fundamental lines or axis of a transit theodolite include the following:- * Vertical axis * Axis of plate levels * Axis of telescope * Line of collimation * Horizontal axis * Axis of altitude bubble and the vernier should read zero. These adjustments once made last for a long time. These are important for accuracy of observations taken from the instrument. The permanent adjustments in case of transit theodolite are:- * Horizontal axis adjustment. The horizontal axis must be perpendicular to the vertical axis. * Vertical circle index adjustment. The vertical circle must read zero when the line of collimation is horizontal. * Adjustment of altitude level. The axis of altitude level must be parallel to the line of collimation. * Collimation adjustment. The line of collimation or line of sight should coincide with axis of the telescope. The line of sight shoul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Bull's Eye Level (level)
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content. During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers, and the gentry, while red was r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodolite Vermeer
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and infrastructure construction, and some specialized applications such as meteorology and rocket launching. It consists of a moveable telescope mounted so it can rotate around horizontal and vertical axes and provide angular readouts. These indicate the orientation of the telescope, and are used to relate the first point sighted through the telescope to subsequent sightings of other points from the same theodolite position. These angles can be measured with accuracies down to microradians or seconds of arc. From these readings a plan can be drawn, or objects can be positioned in accordance with an existing plan. The modern theodolite has evolved into what is known as a total station where angles and distances are measured electronically, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tribrach (instrument)
A tribrach with an optical plummet (the black cylinder pointing to the left lower corner of the image). A tribrach is an attachment plate used to attach a surveying instrument, for example a theodolite, total station, GNSS antenna or target to a tripod. A tribrach allows the survey instrument to be repeatedly placed in the same position over a surveying marker point with sub-millimetre precision, by loosening and re-tightening a lock to adjust the instrument base in a horizontal plane. Components of a tribrach The device consists of two triangular metal plates connected at their corners by leveling thumbscrews, a bubble level, a locking mechanism and often an optical plummet. The centre of the bottom plate of the tribrach has a 5/8-11 UNC thread bolt hole which is used to attach the tribrach to the tripod. The top plate has three small holes or slots spaced 120˚ apart above leveling thumbscrews, and a locking mechanism which enables a survey instrument or target to be accu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Axis
A Cartesian coordinate system (, ) in a plane (geometry), plane is a coordinate system that specifies each point (geometry), point uniquely by a pair of number, numerical coordinates, which are the positive and negative numbers, signed distances to the point from two fixed perpendicular oriented lines, measured in the same unit length, unit of length. Each reference coordinate line is called a ''coordinate axis'' or just ''axis'' (plural ''axes'') of the system, and the point where they meet is its ''Origin (mathematics), origin'', at ordered pair . The coordinates can also be defined as the positions of the orthogonal projection, perpendicular projections of the point onto the two axes, expressed as signed distances from the origin. One can use the same principle to specify the position of any point in three-dimensional space by three Cartesian coordinates, its signed distances to three mutually perpendicular planes (or, equivalently, by its perpendicular projection onto three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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