The Benefits of Ground Control Point Survey (GCPs)

CompassData Ground Control Point Survey (GCPs) is an industry standard for accurate, high-quality surveying. The data accuracy is based on the spatial relationship between the GCPs’ points on the ground and the elevations of the objects they represent. Listed below are some of the benefits of the Ground Control Point Survey and how they can improve your project. Read on to learn more.

Ground Control Points

Ground ControlPoint (GCP) Surveys have many benefits. In addition to ensuring global accuracy, these surveys are often the last word in disputes over property lines. A ground control point survey will allow you to compare plat data to a survey to find out if the lines have shifted since the last time you did a survey. Likewise, you can use ground control points to compare plat data to aerial maps to ensure that the lines still exist.

A necessary tool for aerial mapping

Ground control points (GCPs) are points on the ground that have exceptionally accurate GPS coordinates. These points are placed strategically throughout an area. Ground control points are often visible in aerial mapping. People use GCPs to help the drone software match other points to the map. Because of this, ground control points are a necessary tool in aerial mapping. For example, a surveyor can use GCPs to identify the location of trees, buildings, and other objects, which can help them create accurate elevation maps.

Geoid model

The geoid model uses a standard reference point, usually mean sea level, as the base for all measurements. Remember that the unit of measurement should be stated clearly, whether it is meters, feet, or both. A map projection is used to convert the geoid model to a flat plane. This tool can help you create and validate the elevation of your project’s control points. Here are some of the advantages of geodetic inverse computation using a Geoid model:

You should distribute the ground control points evenly across the site. Clustering them too closely can decrease accuracy. The number of GCPs you utilize should be sufficient to cover the entire area, but not too few.

RTK system

An RTK system is an alternative to the EDM method used for large-scale topographic surveys. EDM requires line-of-sight to perform a survey. RTK is more accurate, less expensive, and less disruptive. It has several advantages over GCPs. Its ability to track and position objects in the field is invaluable when measuring the distance from a vehicle to a point or object.

A dual-frequency GPS unit can achieve centimeter-level accuracy, while RTK communications might take five seconds or less. However, sub-centimeter accuracies require much longer occupation times and are not practical for production-based work. These sub-centimeter applications are mostly used for research, such as detecting geologic deformation. These devices have various applications and are not always the best choice for every project.


You can improve the accuracy of an aerial photogrammetry image using Ground ControlPoint (GCP) surveys. RTK corrects geodata while flying, so aligning the data to the pictures would be redundant. GCPs are beneficial for projects that need to be accurate and reliable. Setting up GCPs is simple, as GCPs are positioned on the ground with GNSS receivers and uploaded to post-processing software. GCPs should be large, well-colored, and with high contrast to be as accurate as possible.

More affordable than traditional aerial photography

The amount of GCPs in a survey directly influences the accuracy of photogrammetric products. Researchers have conducted many experiments to measure the accuracy of UAV products, varying the number of GCPs to obtain the desired results. They have also shown that increased GCP density increases the accuracy of aerial photogrammetry products. While this method is still not widely used, it does have a good reputation for accuracy. In addition, GCPs are more affordable than traditional aerial photography.

An effective way to map a site and measure elevation

There are many reasons to use ground control points (GCPs) in a survey, but none outweigh the benefits. Ground control points can be an effective way to map a site and measure elevation. The GCPs must be half a meter in size and should be painted in a bright, contrasting color with a clearly defined center. GCPs can be self-made or purchased, and the number you need will depend on your survey site’s size. A good rule of thumb is to place them evenly across the survey area so that they remain unobscured by vegetation or trees.

One reason to use GCPs is that they reduce the time needed in the field. GCPs can be used to mark important points like utilities and parking strips. Because the ground is so flat and the colors of the sites vary, it is necessary to have many GCPs. You can complete this survey using a drone in just a couple of hours since a helicopter would take too long to map the site.