Development of an electronic system for field-scale geomorphometric measurements

Terrain attributes are the most studied soil characteristics. Although important, few areas have their topographic features mapped at the field-scale level. These features are vital for the management and planning of production fields. Today, terrain attributes are derived from elevation measurement.; A more direct form of measurement was developed by Rowe and Spencer (1976), pitch and roll angles were used to derive slope gradient and vehicle attitude. Yang (1997) related vehicle attitude to slope aspect. These mathematical models are difficult to implement in low-cost micro-controllers because of trigonometric functions. Research conducted at the Biosystems Department of The University of Tennessee focused on the simplification of the existing models and on the development of an electronic system to test two sensing techniques in dual-axial rotational measurement of a roving vehicle: a clinometer and an accelerometer. Tests were conducted in a topography-variable field of the Blount Experiment Research Unit. Elevation data measured with a RTK-GPS were used to generate an accurate elevation map. Terrain attributes were calculated in 3 spatial resolutions: 4, 16, and 100 m2.; The simplification of the mathematical models relating pitch and roll angles to terrain attributes is possible because of the existing limitations on slope gradient of arable lands. Results obtained during the field test show that slope measurement accuracy varied according to spatial resolutions. The density of points used in the calculation of the terrain attributes also contributes to the measurement accuracy. In general, mean absolute error (MAE) was less than 1° for both sensors in all resolutions tested. Data collected can also be used to detect field elevation changes.; In conclusion, it is possible to rely on measurements of vehicle axial rotation for the computation of field-scale terrain attributes. The sensing techniques tested were successfully used in these measurements. The application of simplified models to derive terrain measurements is possible due to the existing slope gradient limitation of arable lands. An order I map of terrain attributes is possible to be obtained using the proposed electronic system and models. The system can also be used to pinpoint locations of elevation differences in the field.