Method and system for extracting nail contours

A method for a processor extracting nail contours, comprising:

• a step of data acquisition:
• carrying out 3D scanning on a target finger to obtain finger 3D data DataFinger of the target finger, wherein the finger 3D data DataFinger at least include nail 3D data DataNail of a whole nail;
• a step of point cloud processing of data:
• converting the finger 3D data DataFinger into 3D point cloud data to obtain a finger point cloud CloudFinger, wherein the finger point cloud CloudFinger at least includes a nail curved-surface point cloud CloudNail-s of the whole nail;
• a step of nail point cloud acquisition:
• segmenting the finger point cloud CloudFinger to obtain the nail curved-surface point cloud CloudNail-s from the finger point cloud CloudFinger,
• a step of nail point cloud flattening:
• flattening the nail curved-surface point cloud CloudNail-s in an equal surface area manner to obtain a nail plane point cloud CloudNail-p in a planar state;
• and
• a step of nail contour drawing:
• drawing a shape of a contour point cloud CloudContour according to a contour of the nail plane point cloud CloudNail-p to obtain a nail model of the nail,
• wherein the step of nail point cloud acquisition comprises:
• a sub-step of point cloud segmentation:
• segmenting the finger point cloud CloudFinger by region growing segmentation to obtain the nail curved-surface point cloud CloudNail-s from the finger point cloud CloudFinger,
• wherein after the sub-step of point cloud segmentation, the step of nail point cloud acquisition further comprises:
• a sub-step of cluster constraining:
• inputting a search radius Rrs′ smaller than a search radius Rrs based on the search radius Rrs, obtaining an angle θRrs′ between normal vectors of a point and a neighboring point under the search radius of Rrs′, and adding an angle threshold θthres 2 as a judging criterion;
• and
• if a difference between the angles between the normal vectors of the point and the neighboring point under the search radius Rrs and the search radius Rrs′ is greater than the angle threshold θthres 2, stopping growing.

A system including a processor and a memory, used for implementing a method for the processor extracting nail contours, the method includes a step of data acquisition:

• carrying out 3D scanning on a target finger to obtain finger 3D data DataFinger of the target finger, wherein the finger 3D data DataFinger at least include nail 3D data DataNail of a whole nail;
• a step of point cloud processing of data:
• converting the finger 3D data DataFinger into 3D point cloud data to obtain a finger point cloud CloudFinger, wherein the finger point cloud CloudFinger at least includes a nail curved-surface point cloud CloudNail-s of the whole nail;
• a step of nail point cloud acquisition:
• segmenting the finger point cloud CloudFinger to separate the nail curved-surface point cloud CloudNail-s from the finger point cloud CloudFinger;
• a step of nail point cloud flattening:
• flattening the nail curved-surface point cloud CloudNail-s in an equal surface area manner to obtain a nail plane point cloud CloudNail-p in a planar state;
• and a step of nail contour drawing:
• drawing a shape of a contour point cloud CloudContour according to a contour of the nail plane point cloud CloudNail-p to obtain a nail model of the nail, the system comprising:
• a data acquisition unit which is used for carrying out 3D scanning on a target finger to obtain finger 3D data DataFinger of the target finger, wherein the finger 3D data DataFinger at least include nail 3D data DataNail of a whole nail;
• a data conversion unit which is in communication connection with the data acquisition unit, receives the finger 3D data DataFinger and converts the finger 3D data DataFinger of into 3D point cloud data to obtain a finger point cloud CloudFinger, wherein the finger point cloud CloudFinger at least includes a nail curved-surface point cloud CloudNail-s of the whole nail;
• a PCL which is in communication connection with the data conversion unit;
• a segmentation module which is located in the PCL and is configured to segment the finger point cloud CloudFinger to extract a nail curved-surface point cloud of the nail from the finger point cloud CloudFinger,
• a flattening module which is in communication connection with the PCL and is configured to spread and flatten the nail curved-surface point cloud CloudNail-s in an equal surface area manner to obtain a nail plane point cloud CloudNail-p in a planar state;
• and
• a drawing module which is in communication connection with the flattening module, receives the nail plane point cloud CloudNail-p, and draws a shape of a contour point cloud CloudContour according to a contour of the nail plane point cloud CloudNail-p to obtain a nail model of the nail,
• wherein the flattening module is configured to unify x-coordinates of all points pj in each layer of point cloud Li, keep y-coordinates and z-coordinates of the points pj unchanged to obtain an approximately arc point cloud set stand_Li, divide all points p in each layer of point cloud set stand_Li into two parts:
• L_part1i and L_part2i, according to a y-coordinate Centery of a center line of the nail, and finally orders the arc point clouds L_part1i and L_part2i of each layer in a sequence away from the center line of the nail to obtain L_ordered_parti.