To determine the independent coordinates of an existing building. Theodolite Traversing.

Object: To determine the independent coordinates of the existing building.

Equipment:

Digital theodolite, tripod stand, leveling staff, prismatic compass, ranging rods, and plum bob.

Theory:

Tacheometric Surveying (Tacheometry):

It is the branch of surveying in which horizontal and vertical distances are determine by taking angular observations and stadia readings with help of an instrument known as tacheometer. In this survey chaining operation is completely eliminated.

Tacheometer:

It is a transit theodolite, fitted with stadia lines (or stadia diaphragm) and an additional convex lens in the telescope of a tachometer.

Lens formula is 1/f = 1/p + 1/q From figure

1/f = 1/u + 1/v

Since, i/s = v/u => v = iu/s 1/f = 1/u + s/iu

1/f = 1/u(1 + s/i) u= f(1 + s/i)

u+d = f(1 + s/i) + d D = (f/i)s + (f+d)

Procedure:

1. Mark station O then mark North with help of prismatic compass at station O.
2. Set the instrument at station O and done the temporary adjustment.
3. Horizontal clamp is kept fixed and vertical clamp loosened, then set telescope at 90˚ with the help of vertical clamp and vertical screw.
4. Now the vertical clamp is tightly fixed and horizontal clamp is loosened and telescope is directed towards north and bisect the ranging rod.
5. Horizontal clamp is fixed and set horizontal angle as 0˚ by using reset button.
6. Now loose the horizontal clamp and vertical clamp then telescope is directed towards A and bisect the ranging rod at A.
7. Note the H.A. displayed at display screen, which is the bearing of line OA and vertical angle also.
8. Now hold the staff rod on station A and note the stadia readings that is uppers stadia, lower stadia and central stadia readings.
9. Horizontal distance of OA is calculated by using distance formula ( D = (f/i)scos2θ + (f+d)cosθ).
10. Repeat the above process for bearings and distances of other points of building which are visible from station O.
11. To calculate bearings and distances of other points of building which are not visible from station O, Mark another station O1 in such a way it is visible from station O.
12. Take the bearing and distance of O1 from O by above process.
13. Now shift the instrument and take bearings and distances of other points of building which are visible from station O1.
14. Take all readings of points of building by above process.
15. Find the latitude by using LCosθ and departure by using LSinθ (where L is distance of line and θ is bearing of that line).
16. Let the coordinates of point O as (1000, 1000).
17. And find the coordinates of other stations by adding latitudes and departures in coordinates of station A.

Observations:

Calculation for Coordinates of Building;

Determination of Independent Coordinates of an Existing Building Using a Total Station

To determine the independent coordinates (X, Y, Z) of an existing building, a Total Station is used to establish precise positions of key points on the structure. The process involves setting up a coordinate system, measuring reference points, and computing the coordinates.

1. Steps to Determine Independent Coordinates of a Building

Step 1: Establish a Control Network

Before surveying the building, set up a control network using known reference points. These points should have precisely known coordinates (e.g., from a geodetic survey or GPS).

Step 2: Setting Up the Total Station

1. Instrument Setup:
   • Place the Total Station at a stable location near the building.
   • Level the instrument using the built-in circular bubble and electronic leveling system.
2. Orientation (Backsight or Resection):
   • Use a known control point as a back sight for orientation.
   • If no control points are available, use resection by measuring angles and distances to at least two known reference points.

Step 3: Data Collection

1. Targeting Key Points:
   • Identify critical points on the building (e.g., corners, edges, rooflines, doors, windows).
   • Place a prism or use reflectorless mode to measure these points.
2. Measuring Coordinates:
   • Use the Total Station to record the horizontal angle, vertical angle, and slope distance to each target point.
   • The instrument calculates the (X, Y, Z) coordinates based on the known station location.

Step 4: Data Processing

1. Coordinate Computation:
   • The Total Station software automatically converts measured distances and angles into coordinates.
   • If needed, transfer the data to CAD or GIS software for further analysis.
2. Error Checking:
   • Compare measured points with existing plans or site data to ensure accuracy.

2. Applications of Determining Building Coordinates

• Urban Planning: Accurate mapping of existing structures for development.
• Structural Analysis: Monitoring building movement or deformation.
• Property Boundary Surveys: Verifying land ownership and legal boundaries.
• BIM and GIS Integration: Creating 3D models for construction management.