A simple automated laser profile meter

Authors: Polyakov, Viktor; Nearing, Mark

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2018
Publication Date: 4/5/2019
Publication URL: https://handle.nal.usda.gov/10113/6471240
Citation: Polyakov, V.O., Nearing, M.A. 2019. A simple automated laser profile meter. Soil Science Society of America Journal. 83:327-331. https://doi.org/10.2136/sssaj2018.10.0378.
DOI: https://doi.org/10.2136/sssaj2018.10.0378

Interpretive Summary: A simple portable non-contact profile meter was built to measure soil surface elevations. It consists of off-the shelf components (laser distance meter and automated linear rail) and is operated wirelessly from a mobile device, such as a mobile phone. The profile meter is relatively cheap (less than $1500 not including a mobile device) and can be constructed quickly without the need for expert knowledge. The profile meter has good vertical accuracy (±0.07 mm) and precision (±0.2 mm) and can be programed to sample at any horizontal resolution. It works reliably on a wide variety of natural materials under any lighting conditions. It requires no elevation calibration or post processing of the output data. An important advantage over similar systems is vertical orientation of the laser beam and the optical detector, which provides orthogonal view thus minimizing data gaps. The profile meter can be transported and operated by one person. It takes less than 10 min to set up and 1.8 min to measure 200 elevation points. While the proposed apparatus measures elevations only along a single profile, there are many applications where such datasets will satisfy research needs. For example, calculating random roughness of soil, measuring and monitoring channel and rill cross sections, quantifying soil cover, etc. Soil roughness obtained by the profile meter compared well with those obtained by a ground based terrestrial LIDAR. Our apparatus provides a simple and practical alternative to more expensive or operationally complex systems.

Technical Abstract: An automated profile meter with vertical precision of ±0.2 mm was built to measure soil surface elevations. It consists of a laser distance meter mounted on an automated linear motion system. Operation and data logging is conducted wirelessly using a Bluetooth enabled mobile device. The profile meter performed well on variety of surfaces and under various lighting conditions. It is inexpensive (less than $1500), consists of readily available components, portable, and easy to setup in the field (less than 10 min). When measuring soil random roughness the profile meter compared well with a ground based terrestrial LIDAR.