You should use a black and white checkerboard GCP that is either 2ft x 2ft or 4ft x 4ft. We make ours out of plywood and paint.
In order to ensure your LiDAR data is absolutely accurate it is important to get accurate ground control points (GCPs). The placement of these GCPs is important so you can see the location within your LiDAR data intensity view.
For most situations we use a 2ft x 2ft white and black checkerboard pattern for our GCPs. This will give adequate contrast in order to find the center point of the GCP. We typically make ours out of plywood with black and white paint.
Note: Don't apply any reflective tape to your GCPs. This will not help. You are far more likely to get false readings from the sun reflecting off of the tape than it helping you pick out the GCP.
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