High-Quality 3D Fingerprint Generation: Merging Skin Optics, Machine Learning and 3D Reconstruction Techniques

Apoorva Srivastava

Abstract

Fingerprints are a widely recognized and commonly used method of identification. Contact-based fingerprints, which involve pressing the finger against a surface to obtain images, are a popular method of capturing fingerprints. However, this process has several drawbacks, including skin deformation, unhygienic conditions, and high sensitivity to the moisture content of the finger. These factors can negatively impact the accuracy of the fingerprint. Moreover, fingerprints are three-dimensional anatomical structures, and two-dimensional fingerprints do not capture the depth information of the finger ridges. While 3D fingerprint capture is less sensitive to skin moisture levels and avoids skin deformation, it is limited in adoption due to the high cost and system complexity associated with it. The complexity and cost are mainly attributed to the use of multiple cameras, projectors, and sometimes synchronously moving mechanical parts. Photometric stereo offers a promising solution to build low-cost, simple sensors for high-quality 3D capture using only a single camera and a few LEDs. However, the method assumes that the surface being imaged is lambertian, which is not the case for human fingers. Existing 3D fingerprint scanners based on photometric stereo also assume that the finger is lambertian, resulting in poor reconstruction results. In this context, we introduce the Split and Knit algorithm (SnK), a 3D reconstruction pipeline based on Photometric Stereo for finger surfaces. The algorithm splits the reconstruction of the ridge-valley pattern and finger shape and combines them to obtain the 3D fingerprint reconstruction for the full finger with a single camera for the first time. To reconstruct the ridge-valley pattern, SnK introduces an efficient way of estimating the direct illumination component by using a trained U-Net without extra hardware, which reduces the non-Lambertian nature of the finger image and enables a higher-quality reconstruction of the entire finger surface. To obtain the finger shape using a single camera, the algorithm introduced two novel approaches, a) using IR illumination and b) using a mirror and parametric modeling for the finger shape. Finally, we combine the overall finger shape and the ridge-valley point cloud to obtain a 3D finger phalange. The high-quality 3D reconstruction results in better matching accuracy of the captured fingerprints. Splitting the ridge-valley pattern from the finger provides an implicit way to convert 3D fingerprint into 2D fingerprint, making the SnK algorithm compatible with the 2D fingerprint recognition systems. To apply the SnK algorithm to fingerprints, we designed a 3D printed photometric stereo-based setup that captures contactless finger images and obtains their 3D reconstructions

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