[Manish Jain]

New techniques of Land survey
Advanced instruments plays very vital role in investigating their basic technical parameters to improve the engineering, surveying measurements Total station is a combination of an electronic theodolite and electronic distance meter makes it possible to determine the coordinates of a reflector by aligning the instrument cross hair on the reflector and simultaneously measuring the vertical and horizontal angles and slope distance a micro processor in the instrument takes care of recording reading, and the necessary computations. The data is easily transferred to a computer where it can be used to generate a map. The GPS concept is based on time. The satellites carry very stable atomic clocks that are synchronized to each other and ground clocks. GPS satellites continuously transmit their current time and position. GPS provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity and time

1. Total Station survey 
   
2. DGPS survey
   
3. Mobile LiDAR Survey
   
4. UAV /Drone Survey
   

1. Total Station survey 
A total station is a modern theodolite which is a transit fitted with an electronic distance meter (EDM). A microprocessor unit in the total station processes the data collected to determine:

• The average of multiple angles measured.
  
• The average of multiple distance measured.
  
• The horizontal distance.
  
• The distance between any two points.
  
• The elevation of objects.
  
• All three coordinates of the observed points.
  

The data that is collected and processed can be downloaded for further processing by computer aided design (CAD), building information modelling (BIM) or geographic information system (GIS) software.

2. DGPS survey
The DGPS (Differential Geographic Positioning System) Survey
These are surveys which are carried out using the differential GPS. It achieves higher positional accuracy by making use of the differential capabilities of two GPS antenna linked by a radio signal. Each DGPS uses a network of fixed ground-based reference stations to broadcast the difference between the positions indicated by the GPS satellite system and known fixed positions. These stations broadcast the difference between the measured satellite pseudo-ranges and actual (internally computed) pseudo-ranges, and receiver stations may correct their pseudo-ranges by the same amount. The digital correction signal is typically broadcast locally over ground-based transmitters of shorter range.
The DGPS Survey main features are:

• Position is determined by distance from at least 4 satellites
  
• Time taken by signal to travel from satellite to antenna used to determine the distance.
  
• The base station calculates the difference between the specified coordinates of its location and those indicated by the satellites.
  
• The base is continuously broadcasting a signal to the rover of this difference.
  
• The rover then uses this same difference to accurately determine it’s location.
  

DGPS Advantages
Higher accuracy (+/-0.045m) , Real time data , Worldwide coverage
3D survey results , 24 hours availability , Not affected by cloud cover

3. Mobile LiDAR Survey
Mobile LiDAR ( light detection and ranging) is an innovative mapping solution that incorporates the most advanced LiDAR sensors, cameras and position/navigation to collect survey-quality point data quickly and accurately .
Mobile Lidar (also mobile laser scanning) is when two or more scanners are attached to a moving vehicle to collect data along a path. These scanners are almost always paired with other kinds of equipment, including GNSS receivers and IMUs

4. UAV /Drone Survey
Unmanned aerial vehicle (UAV) carrying navigation equipment (advanced autopilot module APM, GPS, inertial measurement unit – IMU),
camera .To create 3D maps from aerial photogrammetry, the camera is mounted on the drone and is usually pointed vertically towards the ground.
Using photogrammetry to create 3D models of monuments or statues, the camera is mounted horizontally on the UAV. Multiple overlapping photos (80 to 90% overlap) of the ground or model are taken as the UAV flies along an autonomous programmed flight path called a waypoint. To overlap photos of an object or land by 80 to 90% would be impossible to complete accurately by pilot navigation. It is essential to have a UAV which has waypoint navigation technology 
There are Sixteen types of UAV available in market 

1. quadcopter UAV
   
2. hexacopter UAV 
   
3. fixed-wing UAV 
   
4. flapping-wing UAV
   
5. single-rotor UAV
   
6. coaxial UAV
   
7. ducted-fan UAV
   
8. octocopter UAV
   
9. glider UAV
   
10. blimp UAV
    
11. ionic flyer UAV
    
12. cyclocopter UAV
    
13. spincopter UAV
    
14. Coanda UAV
    
15. parafoil UAV
    
16. kite UAV .