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What are the basic classifications of the triangulation system?
What are the basic classifications of the triangulation system?
Primary, secondary, and tertiary triangulation.
What is the basic specification of primary triangulation?
What is the basic specification of primary triangulation?
To provide a highly accurate framework of triangulation stations for further precise measurements.
Draw various common triangulation figures and their uses.
Draw various common triangulation figures and their uses.
Triangular and quadrilateral figures, used for establishing control points.
What are the points to be kept in view for selecting the site for a baseline in large surveys?
What are the points to be kept in view for selecting the site for a baseline in large surveys?
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Explain the procedure for reduction to the center of a satellite station.
Explain the procedure for reduction to the center of a satellite station.
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What do you understand by a satellite station and reduction to center?
What do you understand by a satellite station and reduction to center?
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Find the minimum height of the signal required at B if the triangulation stations A and B are 50 km apart and have elevations of 243m and 258m respectively, with a ground elevation of 216m and a minimum sight distance of 2.4m.
Find the minimum height of the signal required at B if the triangulation stations A and B are 50 km apart and have elevations of 243m and 258m respectively, with a ground elevation of 216m and a minimum sight distance of 2.4m.
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Find the minimum height of the signal required at B if the triangulation stations A and B are 60 km apart with elevations of 240m and 280m, a ground elevation of 200m, and a minimum sight distance of 2m.
Find the minimum height of the signal required at B if the triangulation stations A and B are 60 km apart with elevations of 240m and 280m, a ground elevation of 200m, and a minimum sight distance of 2m.
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Ascertain if triangulation stations A and B (100 km apart) are intervisible given their elevations are 180m and 450m respectively, and there is an obstruction at C with an elevation of 259m located 75 km from A.
Ascertain if triangulation stations A and B (100 km apart) are intervisible given their elevations are 180m and 450m respectively, and there is an obstruction at C with an elevation of 259m located 75 km from A.
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Ascertain if two proposed triangulation stations A and B (100 km apart) are intervisible with elevations of 420m and 700m, and an obstruction C with an elevation of 478m located 70 km from A.
Ascertain if two proposed triangulation stations A and B (100 km apart) are intervisible with elevations of 420m and 700m, and an obstruction C with an elevation of 478m located 70 km from A.
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Find the most probable value of A from the following observations: A = 40°32'33'' (weight 2), 3A = 121°42'12'' (weight 3).
Find the most probable value of A from the following observations: A = 40°32'33'' (weight 2), 3A = 121°42'12'' (weight 3).
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Find the most probable values of angles A and B and their summation from the observations: A = 42°20'30.4'' (weight 1), B = 36°18'25.2'' (weight 2), A + B = 78°38'50.3'' (weight 3).
Find the most probable values of angles A and B and their summation from the observations: A = 42°20'30.4'' (weight 1), B = 36°18'25.2'' (weight 2), A + B = 78°38'50.3'' (weight 3).
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Calculate the correct angle ABC from angles measured at station S, LBSC = 76°25'32'', LCSA = 54°32'20'' with lengths AB = 5286.50 m and BC = 4932.20 m.
Calculate the correct angle ABC from angles measured at station S, LBSC = 76°25'32'', LCSA = 54°32'20'' with lengths AB = 5286.50 m and BC = 4932.20 m.
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Give the corrected value of the angles for triangle ABC recorded as follows: A = 77°14'20'' (weight 4), B = 49°40'35'' (weight 3), C = 53°04'52'' (weight 2).
Give the corrected value of the angles for triangle ABC recorded as follows: A = 77°14'20'' (weight 4), B = 49°40'35'' (weight 3), C = 53°04'52'' (weight 2).
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Study Notes
Triangulation Principles
- Triangulation uses interconnected triangles.
- Only one side (baseline) length and all angles are measured precisely.
- Other triangle sides are computed using trigonometry.
- Triangulation station: Apex of each triangle.
- Triangulation system/figure: The whole interconnected network.
- Error accumulation is a drawback; subsidiary bases help control this.
Triangulation System Classification & Specifications
- The provided text does not offer a classification of triangulation systems aside from mentioning primary triangulation which is designed to provide accurate horizontal control points for less precise surveys.
Triangulation Figures & Station Selection
- Different triangulation figures exist (specific examples not provided).
- Site selection for baselines in large surveys requires careful consideration (specific criteria not detailed).
Satellite Stations & Reduction to Center
- Satellite station: A station not at the main triangle apex but whose angles are measured.
- Reduction to center: A calculation to correct measurements taken from an eccentric station (like a satellite station). The process corrects for the error introduced by observing from a point other than the main station. Specific formulas or procedures for this calculation are not described.
Intervisibility & Signal Height
- Intervisibility: Determining if two stations can see each other. Calculations involve considering elevation differences and intervening obstructions.
- Minimum signal height calculations: Examples are given to determine necessary signal height to ensure clear line of sight, accounting for intervening ground elevation and a minimum clearance above ground level.
Baseline Measurement & Corrections
- Baseline: The single measured length in the triangulation network.
- The text notes the existence of corrections needed for baseline measurements, but those correction specifics are not given.
Fieldwork & Data Adjustment
- Reconnaissance: Preliminary survey to identify suitable station locations.
- Angular measurements: Precise measurements of angles within the triangles.
- Adjustment of field observations: Techniques such as least squares adjustment are used to minimize errors in the observations. More detail on the process is not provided.
- Weighted observations: Observations with different levels of precision are assigned different weights to account for their relative reliability in the adjustment process.
Error Analysis
- Errors in observation: Sources of error in angle and baseline measurements (types not elaborated upon).
- Method of least squares: A mathematical technique for adjusting measurements to obtain the most probable values.
- Figure adjustment: A method of adjusting angles in the triangulation network, only the triangle adjustment is mentioned here.
Example Calculations
- Several examples show calculations for determining intervisibility, and minimum signal height considering ground elevations and required minimum clearance.
- Examples of least squares adjustment are provided for single angle and multiple angle/summation calculations with different weights.
- Example of reduction to center for an eccentric station is described.
Objectives of Triangulation
- Establishing a highly accurate horizontal control network supporting less precise surveys.
- Contributing to earth shape and size determination through latitude, longitude, and gravity observations.
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Description
Explore the fundamental principles of triangulation, including the use of interconnected triangles and the importance of baseline measurements. Understand the classification of triangulation systems and the considerations for selecting triangulation figures and stations. This quiz will test your knowledge on how these elements contribute to accurate surveying.
