Microrelief meter for field topography measurements

The design and evaluation of an automated, non-contact microrelief meter for measuring soil surface elevations under field conditions are presented. Key factors in the design of the meter are measurement accuracy, data-collection speed, and portability. Surface elevations are measured by determining the location of a laser line using image-processing techniques. The accuracy was evaluated using blocks of known dimensions. Measurement errors in the x, y and z directions were approximately ±0.25 mm, ±1.5 mm, and ±0.5 mm, respectively. These errors include those caused by the resolution limitations of the image-processing system, shaft encoders, as well as mechanical errors caused by the deflection of the support frame. The system was used to gather microtopography data from field erosion plots. The microrelief meter was able to gather more than 650,000 elevation data values in approximately two hours. Overall, the system was well suited for field topography measurements.