A Processing Framework for Tree-Root Reconstruction Using Ground-Penetrating Radar Under Heterogeneous Soil Conditions
Abderrahmane Aboudourib, Mohammed Serhir, Dominique Lesselier
Abstract
Since tree roots are important to ecosystems, particularly in the context of global climate change, better understanding of their organization is necessary. Ground-penetrating radar (GPR) appears a useful tool to that effect. In this contribution, a novel processing procedure to reconstruct 3-D root architectures from GPR data in heterogeneous environments is proposed, involving three main steps: 1) noise-related information is removed using singular value decomposition (SVD); 2) a modified version of randomized Hough transform (RHT) yields the soil dielectric constant; and 3) a matched-filter technique combined with Hilbert transform then operates as wave migration. Viability is first studied from comprehensive numerical simulations carried out with the gprMax software on a realistic root model in a 3-D heterogeneous environment. The heterogeneous soil effect is studied carefully through a number of simulations involving six different soil types. Then, controlled laboratory measurements are conducted on a root prototype using a bistatic GPR system involving folded complementary bowtie antennas in the frequency range of 300 MHz to 3.3 GHz. The 3-D results from both simulations and experiments show the good performance and potential of the proposed processing.