Land surveying is a technique of determining the terrestrial or three-dimensional position of points and the distances and angles between them.

To measure these, high order GPS, Robotic Total Stations and terrestrial scanners have been traditionally used to map an area and make further computations.

Further, surveyors then use software, such as CAD and GIS software to draft plans and map the onsite measurements. Surveyors work on a diverse variety of projects from land subdivision and mining exploration, to tunnel building and major construction projects. The outputs provide information to guide the work of engineers, architects and developers.

Over the past few years, drones have started to emerge as a prominent tool used in surveying. We have observed that using a drone can vastly reduce the time spent collecting accurate data.

By acquiring raster data from the sky – in the form of geo-referenced digital aerial images, with resolutions as sharp as 1.5 cm (0.6 in) per pixel – you can gather millions of data points in one short flight.

Large jobs that once took weeks can now be completed in just a few days, and a week’s worth of traditional data collection is now achieved in just one day.

For example a survey of a 1000 acres estate in 5 days – 2 days on the field and 3 days of image processing and post processing to generate all the outputs. This typically takes 3-4 weeks to get done by the traditional surveying methods

In this blog, we have detailed the steps involved in using drones as a tool for surveying

Developer required a survey to be done on a property to get the following outputs:

• Boundary drawing
• Contours
• Feature marking

The property owner was also keen on being able to visualize the property features to be able to make decisions on designing the project.

Their first go to tool was Google Earth. However, the satellite image was not of sufficient resolution for them to visualize the features accurately. Also, the satellite image was over 6 months old and seemed to indicate some differences in features as compared to the present status.

After understanding the requirement, we suggested to that while an aerial video was one possible output from a drone, We can use drones with ground control points as a tool for survey, which can deliver all the survey outputs they needed, plus provide them visualization that they had not thought possible before – high 2D orthomosaic with the boundaries marked, 3D textured model of the site and a digital surface model.

Accuracy (10 cm)

• The contours overlayed on the high resolution orthomosaic (5cm/px) simplified the process of identifying how the contours run over the different parts of the property.
• Feature identification and marking became extremely accurate as the customer used the orthomosaic as the base layer to design the project.
• The 3D model gave the customer a clear idea of the undulations of the terrain, which helped them arrive at design decisions quicker.
• Since the boundary was created using the visible markers, the exact area of the property was verified accurately.