Topographic Surveys are used to identify and map the contours of the ground and existing features on the surface of the earth or slightly above or below the earth's surface viz. buildings, roads, walkways, manholes, utility poles, retaining walls, trees, etc. A topographic survey is usually performed by professional Land Surveyors with the goal of producing two-dimensional maps which represent three-dimensional components of the landscape. The purpose of a Topographic Survey is to collect survey data about the natural as well as man-made features of the land, and its elevations. The survey shows the relative positions and elevations of both natural and man-made features on a property.
Topographical surveys are also referred as contour surveys and they are always conducted before there is any change in the ownership of the land or even when the property owner is willing to make some changes in the land. The main focus of the topographical surveys is to provide you with the exact figures of the size, height, position of the different changes that have occurred in course of time with regard to their presence of their natural existence.
Every site is different and presents specific risks and challenges. We at “Prashant Surveys”, have shifted from the primitive method of DGPS & ETS (Electronic Total Stations) to the modern innovative method of DGPS, mobile LiDAR and UAV / Drone for medium to huge and complex sites.
We have procured a DGCA type approved Survey Grade PPK UAV / Drone ‘Lookout VTOL’ from TAS, Bangalore, in 2018, with onboard PPK NovAtel GNSS for data capture and ‘Pix4D Professional Mapper’ software to produce accuracy upto 10 cm in X, Y, Z coordinates. This technology can be used to supplement the Mobile LiDAR data output in case of urban mapping projects, or highways projects having proposed bypass roads. This is also ideal for carrying out Topographic Survey of any land where speed and accuracy is of priority, with the rates better than the primitive Electronic Total Station (ETS) method of survey.
The use of such UAV / Drone is ideal for 3D mapping of the smart cities and Town Planning projects in India. About 1 to 1.5 Sq. Km. area can be easily captured by one PPK Survey grade Drone flying with an altitude of about 80 to 100m above average ground level. The Ground Sampling Distance (GSD) obtained varies from 1.5 cm to 5 cm using the Sony Alpha 6000 camera. Where as the accuracy of 10 cm can be obtained in X, Y, Z coordinates using the onboard PPK NovAtel OEM 7700 GPS / GNSS receiver.
The data processing and further output is done using two licenses of Pix4d Professional Mapper Photogrammetric Software and dedicated higher end workstations available with us. Contours can be generated at required intervals say 0.5 m or 1 m, using this photogrammetric data and drawings are prepared up to the scale of 1:1,000 which is sufficient for planning and development of any infrastructure project.