Topographic surveying, also known as contour surveying, is a type of land surveying that establishes the relative location of points above, on, or below the earth's surface. It is a process of determining natural and man-made features on a landscape or property by measuring elevations, directions, and distances. Topographic surveying is often used to map and classify the contours, terrains, and other existing features of the site.
Topographic survey is done prior to changes to the property or if there will be a change in property ownership. This type of land survey is very useful for the environmental sectors, industrial owners, and construction industries. The chief aim of topographic survey is to find out the natural and man-made features on the land by providing exact measurements and charts regarding any improvements or gradual changes in size, location, height, and position that may have occurred over time.
Topographic survey focuses more on the measurements of elevation than on horizontal features, unlike residential or boundary surveys. The results are presented on a map in the form of contour lines. Sophisticated computer software programs and various state-of-the-art equipments make it possible for engineers and architects to utilize digital maps and interactive elevation views of the land according to the changes or improvements they plan to make. A number of of these technically advanced devices are:
* CAD (Computer Aided Design) programs such as AutoCAD, Microstation, and Terramodel
* Digital Photogrammetric Cameras – used for digitally photogrammetric mapping
* Electronic Distance Measurement (EDM) – uses light and radio waves to measure distance
* Global Positioning System (GPS) – satellite imagery that uses more detailed images for mid-scale and even large-scale mapping
* Light Detecting and Ranging (LiDAR) – a laser-based survey technology that allows rapid capturing of highly accurate and thorough data around any land surface
The chief function of topographic surveying is to produce a three-dimensional report of a particular property or land. The representation includes natural and man-made features (which are shown as symbols, texts, and lines), in addition to elevations and heights (shown as contours and spot levels).
Topographic survey serves many purposes such as:
* as required by the government
* devise and establish the most useful strategy for site grading, drainage ditches, and other features by means of the natural landscape
* gives a detailed inspection and facts regarding the property that was formerly used which can have a significant impact on the construction plans and designs
* make sure that the features of the land will be suitable for its projected function or use
*pinpoint minute details like slopes or any elevations on the land which is vital especially when planning to build on the site
* provide the framework or starting point on the land for the majority of construction projects
* the results of the survey are used by architects and engineers to plan the construction of buildings or to make some modifications or developments on the property
Topographic survey maps are crucial in the development stages of construction projects. The survey maps serve as a guide in the design and layout of the site of buildings, landscapes, roads, dams, pipelines, fire control routes, etc. The following are the steps involved in making a topographic map:
* set up horizontal and/or vertical control
* establish sufficient horizontal location and elevation (known as side shots) of ground points to provide enough information for plotting the map
* specify the natural and man-made features found on the land
* calculate distances, angles, and elevations
* Draw the final topographic map
This type of survey chiefly aims to create topographic maps from all the collected data. These maps are utilized by a large number of experts and professionals from architects, engineers, foresters, geologists, etc. Topographic maps are typically prepared in an office after all the data from the survey are gathered, or it can be made right away on the site.