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GCP Best Practices for Aerial Surveying Projects

Ground Control Points (GCPs) are a crucial part of aerial surveying. They help make sure the data collected is as precise as possible. If you're in the surveying industry, it's important to know the best ways to place GCPs to get the best results from your aerial surveying projects. In this article, we'll go over some important points to consider when placing GCPs and some best practices for getting the most out of them.



Key Considerations


Marking Aerial Targets


We advise against using reflective tape, also known as retro-reflective materials, for your targets as it can cause a heavy reflection around the target which can negatively impact the accuracy of your results.


To create an effective aerial target, use a large object with high color contrast (e.g., black and white) that is visible from the air.


Here are a few examples to consider for purchase:


4x4 Checkerboard Pattern


4x4 Chevron Pattern


Visibility

One of the main things to keep in mind when placing GCPs is visibility. You want to make sure the points are easy to see and access, so use durable markers or flags to mark them. This way, it's easy to find and identify the points when collecting data from the air.


Location

It's also important to consider the location of the GCPs relative to the area being surveyed. You want to place them in a way that allows for accurate and precise measurement of the collected data points. For example, if you're collecting data from a large area, consider placing GCPs at regular intervals to ensure the whole area is accurately mapped.


High-contrast GCPs show up easily when you import point cloud data into ROCK Cloud.

Placement Accuracy

Accuracy of location and elevation is another important factor to consider when placing GCPs. You need to ensure you accurately record each GCP's location and elevation as this information is used to calculate the coordinates of the data points being collected. To ensure accuracy, you might need to use precise surveying equipment like GPS or total stations to measure the location and elevation of the GCPs.

 

Related: Use ROCK Cloud's Auto Align GCP tool to dial in your GCPs quickly.