Plane table surveying ppt
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Plane table surveying is a graphical surveying method where field work and plotting are done simultaneously without the use of a field book. The key accessories of a plane table setup include the plane table, alidade, spirit level, trough compass, and U-fork with plumb bob. There are three main methods used - radiation, intersection, and traversing. Some benefits are that it is a rapid method, errors can be easily detected, and irregular objects can be accurately represented. However, it is not suitable for highly accurate work or in inclement weather conditions.
Plane table surveying ppt
- 1. PLANE TABLE SURVEYING ( 8 marks)
- 3. 1a.Explain the functions and use of given accessories of plane table survey 1d.Compare the given two methods of doing plane table survey 1b.Describe the method of orienting the plane table in given situation 1c.Select the method of plane tabling for given situation 1.Use plane table survey to prepare of 5 sided closed traverse by Radiation method 3.Use plane table survey to prepare plans and locate details by intersection method 4.Use plane table survey to prepare plans and locate details by traversing method a. Prepare plans using Plane Table Surveys 5.Use plane table to carry out Survey Project for closed traverse for minimum 5 sides around a buildings UOs PrOs COs
- 4. Introduction Plane tabeling is graphical method of surveying. Here, the field work and plotting are done simultaneously Such survey does not involve the use of field book
- 5. Suitability It is mainly suitable for filling interior details when traversing is done by theodolite Sometimes traversing by plane table may also be done But this survey is recommended for the work where great accuracy is not required
- 6. Principle The principle of plane tabeling is parallelism, meaning that rays drawn from station to the object on the paper are parallel to the lines form the station to the object on ground. The relative positions of the objects on the ground are represented by their plotted positions on the paper and lie on respective rays. The table is always placed parallel at each successive station to the position it occupied at starting station
- 7. Accessories of plane table Accessories Plane table Alidade Spirit level Trough compass U fork with plumb bob Plane alidade Telescopic alidade
- 8. Plane table It is a drawing board of 750X600 mm made of well seasoned wood like teak, pine etc. The top surface of it is well levelled. The bottom surface consists of threaded circular plate for fixing the tripod on the tripod stand by wing nut. Function: It is meant for fixing drawing sheet over it.
- 9. Plane table
- 10. Alidade a)Plain alidade: It consists of metal or wooden ruler of length about 50 cm. One pf its edge is beveled and is known as fiducial edge. It consists of two vanes at both ends. One is called as Object vane which carries Horse hair and other is called Sight vane which has a slit.
- 12. Alidade b) Telescopic alidade: It consists of telescope meant for inclined sight or sighting distant object clearly. This alidade does not have vanes but is provided with fiducial edge. Function of alidade: The function of alidade is to sight object. The ray should be drawn along fiducial edge of alidade.
- 14. Spirit level Spirit level is a small metal tube consists of a small bubble of spirit. The bubble is visible on the top along a graduated glass tube. Function: The spirit level is meant for levelling the plane table.
- 15. Trough compass Trough compass is rectangular box made of non magnetic metal containing a magnetic needle pivoted at the center. It has 0 mark at both ends to locate N-S directions. Function: 1.It is meant to mark north direction on drawing sheet 2.It is used for orientation of plane table
- 17. U-fork with plumb bob It is a metal strip bent in a shape of U( hair pin) having equal arm lengths. The top arm is pointed and a bottom arm carries a hook for suspending a plumb bob. Function: This is meant for centering the table over station.
- 19. Setting of plane table Fixing the table on tripod stand Levelling the table Centering the table Marking the north line Orientation
- 21. Orientation by magnetic needle
- 23. Methods of plane table surveying Methodsofplanetable surveying Radiation method Intersection method Traversing
- 24. Radiation Method
- 27. Merits/Advantages of plane table surveying It is most rapid method of surveying There is no need of field book thus problem of mistakes in booking field notes does not arise Plotted work can be compared with actual object regardless of weather or not they are properly represented There is no possibility of overlooking any important object There is no possibility of overlooking any measurements as plotting is done in field
- 28. Merits/Advantages of plane table surveying Irregular objects can be represented accurately It is suitable in magnetic areas The map can be prepared easily and does not require any great skill Errors in measurement and plotting can be detected by check lines Inaccessible points can be easily located by intersection
- 29. Demerits/Disadvantages of plane table surveying The plane table is not suitable for accurate work as the fitting arrangement is not perfect Plane table surveying is not suitable in wet climate, in the rainy season, on foggy mornings and in windy weathers The number of accessories required in such survey are large and they are likely to be lost The instrument is very heavy and difficult to carry The map cannot be replotted to a different scale as there is no field book
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