Comparing two measuring methods of soil microtopography

Soil surface roughness (SSR) is a critical variable for retrieving soil moisture using microwave remote sensing model. To quantify SSR, the data of soil surface microtopography (SSM) is needed. SSM is the micro elevation of soil surface. The methods of microtopography measurement mainly include the pin meter and profile meter, photography, laser scanning. A method of laser scanning is considered the accurate measurement of microtopography in these methods, but need a very bulky device for field survey. It is necessary to introduce a new device which is precise and portable for microtopographic measurement. In this study, two devices, an Instantaneous-Profile Laser Scanner (IPLS) and a Structured Light 3D Scanner (SLS), would be investigated in the measuring of SSM. The portability of device, the capability of data acquiring, and the precision of two methods were compared with an experiment. With a practical measuring process, it was found that the portability of structured light 3D sensor is excellent. For the capability of acquiring data, the Instantaneous-Profile Laser Scanner is weak than structured light 3D sensor because of view angle of the camera, it cannot deal with the shadow effect very well. For the precision, the result showed that the precision of structured light 3D sensor is a little less than laser scanning because of the limitation of its spatial resolution. All of above, it is believed that structured light range image technology would be very useful on measurement of SSM, and structured light 3D sensor would be very popular in soil roughness measurement.