SLD: A Novel Robust Descriptor for Image Matching

Image matching based on local features is a challenging task because it is difficult to build a robust local descriptor which is invariant to large variations in scale, viewpoints, illumination and rotation. To address these issues, Scale Invariant Feature Transform (SIFT) descriptor has been proposed to build a robust and distinctive local descriptor. However, it is not fully affine invariant. In this letter, we propose a novel robust descriptor: Sampling based Local Descriptor (SLD) to perform reliable image matching under large variations in scale, viewpoints, illumination and rotation. We build the descriptor based on elliptical sampling which samples image pixels according to the elliptic equations. The main advantage of elliptical sampling is that two controllable parameters of elliptical sampling can generate descriptors with different viewpoints and rotations. Besides, the descriptor has two notable properties: 1) it is fully invariant to affine changes; 2) it enables fast matching process because we only need to search two controllable parameters for elliptical sampling, which is more efficient than other affine invariant descriptors. We test the proposed descriptor on standard benchmark for evaluation. Experimental results show the robustness of the proposed method under large variations in illumination, viewpoints and scale.