To carry on from our last article on Topographic Surveys with Drones, in this article, we'll dive deeper by answering the following questions: What is a Topographical Survey? How are Topographical Surveys useful? What are the methods of conducting a Topographical Survey? What is the difference between Real-Time Kinematic and Post-Processing Kinematic? and What outputs can you expect from a topographic survey? Keep reading to learn about how you can #ONEUPYOURBUSINESS!
In the simplest term, a topographical survey is just a collection of coordinates and height measurements for a designated area that will produce different outputs: elevation profiles, contour maps, terrain models, etc. The area's features, such as human-made structures, vegetation, etc., aren't strictly considered topographic information.
Topographical surveys provide several sectors with invaluable information to develop and deliver their projects. Elevation profiles and contour maps aid in the decision-making process of earthworks, excavations, preventing potential flood areas, terrain restructuring (flattening, for example).
Traditionally, when conducting a topographical survey, to make sure that the outputs have the correct scale, first and foremost, you'd mark the area's boundaries and place Ground Control Points (also known as GCPs) and get their coordinates with a handheld GPS device. Ideally, you'd only use calibrated GCPs and handheld GPS devices to ensure accuracy and precision. After this, you'd lay the grid lines across the area and go through the painstaking process of moving the total station around to acquire the dataset and move on to processing it into the elevation profiles and contour maps.
Fortunately, technology has come to the rescue, and tools like drones and Software suites have dramatically improved the survey workflow. You no longer need to spend countless hours walking around the area, carrying the total station, and paying attention to the terrain to avoid tripping over and injuring yourself. Just hire a drone operator, get them to come to your land, and the drone will do all the hard work in a matter of hours.
By using drones on your upcoming survey, you can get numerous advantages over the traditional methods:
As we explained earlier, to ensure that the topographic map is to scale, you'd use calibrated GCPs and handheld GPS devices. This traditional method is still relevant today with drone technology, as you can import the GPCs into the outputs.
As useful as GCPs are, the best survey-grade drones often come equipped with positioning-correction technologies: Real-Time Kinematic (RTK) and Post-Processed Kinematic (PPK) to receive much better accurate and precise measurements. The main differences between RTK and PPK are:
The most common outputs of a traditional topographic survey are the elevation profiles, contour maps, and terrain models, all in a CAD-compatible format. If you have used a drone, you can also expect 3D models, orthomosaics, digital terrain models, and digital surface models.
Bear in mind that most drone operators or surveyors won't go to the extent of making the outputs fully BIM-compatible.
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