1. Geographical Information Systems (GIS): GIS has contributed a lot to the mapping revolution in 21_st century. GIS makes it possible to combine layers of digital data from different sources and to manipulate and analyze how the different layers relate to each other. The process of converting the three (3D) topographic maps to digital form involves raster to vector conversion using CAD-based software such as AutoCAD.
2. Total Station or Theodolite Surveys: The total ststion or theodolite measures the angles, and the distances are measured with either a steel measuring tape or, more commonly, an electronic distance meter (EDM). An EDM can measure great distances (several kilometres) very quickly and accurately. It measures distance with the usage of light and radio waves. Its development was a milestone in survey measurement methods.
3. GNSS or GPS: A constellation of Global Navigation Satellite System (GNSS) or Global Positioning System (GPS) satellites orbiting the earth is used to determine the position(s) of GPS ground receivers as they are moved from one point to another. The collected data may either be processed in the office to produce GPS receiver positions (control surveys) or in the field to give the field surveyor immediate receiver positions (real time GPS surveys) for use for example in construction or for subdivision layout surveys.
4. LiDAR Technology: Airborne LIDAR (Light Detection And Ranging) systems can produce extremely accurate elevation models for terrain (even measuring ground elevation through trees), while offering a quick and efficient method of surveying terrain that is not easily accessible. LiDAR, like the similar radar technology (which uses radio waves instead of light), determines the range to an object by measuring the time delay between transmission of a pulse and detection of the reflected signal.
5. Photogrammetry: In this method, stereographic pairs of photographs are used to indirectly measure objects on the ground and then calculate point coordinates and height differences.
6. UAV or Drone Technology: Unmanned Aerial Vehicles popularly known as drones have become one of the greatest innovations in aerial mapping realm. Drones can be used to execute topographical surveys at varying accuracies. Drones fly at height of approximately 100 to 150 metres above the ground level capturing images at a resolution of 3cm. The images can then be processed to create DSMs, DEMs and topographical maps with contours.

1. The first step is plan and carry out a reconnaissance or pre-visit to the project site to get acquinted with the general landcape of the site, location where the secondary controls will be established and whether bush clearing is required.
2. Once an ideal location has been identified, the establishment of both horizontal (x,y) and vertical (z) ground control points is done and coordinates precisely observed using Static Survey method.
3. The observed static coordinates are then post-processed & survey adjustment done to ensure that GNSS observation errors are eliminated. This is often done using a PC software e.g. EZSURV for performing a survey network adjustment by least squares.
4. Once the horizontal and vertical control points have been established, readings are made from a total station or geodetic GPS (RTK) placed on the known points. The readings on features within the project area (e.g. edge of road, fence, corner of building, tree etc) are picked in 3D format i.e. X, Y and Z.
5. Topographical survey is often carried out by recording the coordinates of features using GNSS i.e. base (known GCP) and rover configuration. The data logger with field software e.g Field genius records and stores the coordinates.
6. Sometimes the primary control points my be close to the project area. In such a case, a simple closed traverse between two known controls can be done using equipment such as a theodolite or a total station to establish the other secondary control points to be utilized in conducting a topo survey.
7. If the topographical survey is to be executed using a total station (TS), then the location of known control points must have a clear line of sight for orientation purposes whilst computing the join. Survey using a total station may take longer time as compared to the GNSS. Just use the right equipment for the right job.
8. Upon completion of field survey work, the data is downloaded back in office, analysed and processed using a software such as AutoCAD Civil 3D to generate contours, Digital Terrain Model (DTM), Digital Elevation Model (DEM), Cross-section and longitudinal profiles as well the topographical map.
9. When preparing the topographical map it is important to consider the contour interval to adopt as well as the map scale. These parameters often vary depending the the requirements and specifications from the client. One GNSS base can also serve many rovers!

Topographical Survey Outputs or Products

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