Capturing LiDAR after a rain event

ROCK R3 PRO
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We got this question from a customer and thought it would be great to upload it to the community:

Is it advisable to not fly after a rain event (wet pavement)?

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Flying a LiDAR system after a rain event when the ground, including pavements, is wet can introduce certain challenges and considerations. Here are some points to ponder:

  1. Reflectivity Changes: Water can change the reflectivity of surfaces. A wet surface will reflect the LiDAR pulse differently than a dry one. This change in reflectivity can introduce variability in the LiDAR return signals.
  2. Water Puddles and Ponds: After a rain event, there can be puddles and ponds on the pavement. Water bodies have a different reflection characteristic than solid pavements. Water, especially if it’s clear and calm, can absorb much of the laser energy or reflect it at a different angle. This can result in data gaps or variations in LiDAR return strength.
  3. Saturation and Specular Reflection: Wet surfaces can cause specular reflection, where the laser pulse is reflected away from the LiDAR sensor instead of back towards it. This can result in reduced signal strength or missed returns.

In order to collect the best data possible, I would not recommend flying after a rain event.

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I scanned the interior of a warehouse once that had been leaking so there were puddles throughout (less than 0.5” in depth). The water caused an inverse reflection of the LiDAR data so we ended up with a mirror image of part of the warehouse inverted underneath the LiDAR data. Upside Down anyone?

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Lots of Stranger Things feels. Would love to see that data set!

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No. The defraction and change in reflections could cause noise and inaccuracies in your point cloud.

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We’ve had measurable reflections occur when facade scanning large windows/glass.

At first I was wondering why the Bolt Supply House had a Christmas tree in the back of their shop. Odd, I thought… so do the lawyers and the insurance people! Why not the surveyors?

Thankfully, we figured this out before we unpacked our Christmas tree… it was reflections from the trees/shrubbery (Knights of Nee?) outside.

Cheers!

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I agree, I just wanted to see the reflection/ghost in his data set