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Understanding Ground Control Points for UAV Operations

piloting tips Mar 03, 2019

 

If you’re reading this, wondering whether your next mission should include Ground Control Points (GCP’s), then you’re in the right location! (Global Accuracy within 1-2 Articles haha)

 

As a drone service provider, it’s essential to find new ways to differentiate yourself in this emerging market. As new technology and equipment begin to surface, it’s hard to tell what you absolutely need in order to adapt, and what you might be able to live without.

 

Ground Control Points are something that we‘ve received numerous questions regarding from drone service providers across the United States. With such a high price point, you want to be absolutely sure that they are required in your line of work before you move forward with a purchase like that.

 

In this article, we will assist you in the process of deciding whether GCP’s are right for your business, the benefit/accuracy of the technology, and how to use them when you’re out in the field. In addition to our discussion topics for today, I always like to finish off these articles that I write with a few personal case studies that outline the ways AltitudeU has leveraged a direct return on investment in the field.



What are Ground Control Points?

 

Ground Control Points, or GCPs, are marked points on the ground that have a known geo-referenced location. If you are unfamiliar with the term “Geo-Referenced” I would highly suggest looking it up with regards to drone technology so you can have a better understanding of how your drone collects data as it takes pictures, flying autonomously in a grid pattern.

 

As you collect data onsite, you can improve the quality of data by adding another factor to the equation. These large marked targets or GCP’s that you place strategically across the site location allow you to collect coordinate data that will help you acquire more accurate information for your client. This method of data collection provides the most value to clients that are in need of land surveying, and construction analysis. Keep in mind, the majority of your projects will not require Ground Control Points, but let’s review a few scenarios that would.



Use Case and Accuracy

Coordinate Based Data: Volumetric, Distance and Area Calculations

 

Best Case Scenario: You are a drone service provider who has the ability to collect accurate data with his/her drone, and that data increases in accuracy with the help of Ground Control Points. You get subcontracted by a Construction & Development company to fly on a weekly basis and create orthomosaic maps that will be uploaded to a data processing software like DroneDeploy, Propeller, or Pix4D - Your contract with them allows company-wide (Civil Engineer, Project Manager, and Investor) access where they can track the progression of their development over the 36 months long process to keep everyone involved with the operation up to date in near-real time. In addition, the Civil Engineers get to utilize your data on a daily basis through the DroneDeploy, Propeller, or Pix4D login credentials you provide the team with, and they can carry out Volumetric, Distance, and Area Calculations to make better business decisions onsite saving them time, and money.

 

This situation would require Ground Control Points to ensure accuracy and consistency within the maps/models being delivered to your client. If your client is going to be making decisions with your data that will affect a 200 Million Dollar Development, you’d better be sure to utilize coordinate-based data that will allow your mapping software to accurately position your map in relation to the real world around it.



Land Surveying: Topographic, Contour & Grading Information

 

Best Case Scenario: You are a drone service provider with the ability to collect 1-2 cm accuracy using a reliable system, coupled with a base station and upwards of 5-10 Ground Control Points onsite. You have been hired by a Construction & Development company to carry out a land survey. There is nothing but dirt onsite, and you are working together with a registered land surveyor, or civil engineer to sign off on your work. You place your ground control points, wait 45 minutes and start your autonomous mapping mission. Once you’ve collected the data, you upload it to your data processing software, import your GCP data and export a file type that you can review with the licensed surveyor that you have subcontracted to double check, analyze and sign off on your work.



Types of Surveys

 

Property Surveys

 

Property Lines have been a disputed topic since the beginning of mankind. Generally, in the pre-construction process, it is essential to have an extremely accurate representation of where the property lines lay. Using aerial data collection, a drone can generate a map that will be used as a base sheet to overlay previous property line data to determine if the line has moved. The map needs to be accurate and can be a defining factor in the final stages of a property line dispute.



Insurance Assessments

 

There are many natural disasters that can take place without a fair warning, and as an insurance assessor, it’s imperative to have accurate data on an area or plot of land that could potentially be affected. The most common type of data being collected throughout a process like this is elevation and contour data which can be used to compare the environment before/after.



Liability

 

As a contractor, your job is to ensure there is an accurate record kept throughout the extent of the development of a building. Having survey grade accuracy collected at various stages in the development will reduce the liability if anything were to go wrong after the project has been completed. Having documentation that the work provided was kept up to code can save millions of dollars in the end.



Breaking Ground

 

These types of general surveys are to be completed by licensed surveyors and are actually required by state and federal regulations. The method in which you collect the data needs to ensure accuracy, and the licensed surveyor that signs off on a map generated by drone data should definitely be involved in the process from start to finish.



Hopefully, this article has helped you grasp Ground Control Points, and their typical use cases.

 

Our team has worked with GCP’s for over 5 years and can provide additional insight to anyone looking to get started. If you are interested in learning more about Ground Control Points, or where to purchase them please feel free to reach out to us at [email protected]

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