## 1 Introduction  
In the era of Industry 4.0, consumers are paying more and more attention to the demand for personalized products. With the cooperation of E-commerce and mobile terminals, a variety of commodities have emerged in APP stores, resulting in an increasing demand for users to carry out simple and feasible model reconstructions of real scenes and objects. Shoes and clothing, medical treatment and other industries are collecting 3D big data of the human body to achieve high-end personalized product manufacturing [1]. Shoe manufacturers also hope to design and produce shoes that accord with the physiological characteristics of the human body to make their customers more comfortable [2]. More and more, users hope to obtain a 3D foot model in a convenient way without leaving home. To achieve this goal, the first step is to achieve fast and automatic measurement of foot parameters.  
Accurately measuring users' data has become an exigent and intractable subject for high-end customization. At present, most companies still use backward traditional contact manual measurement methods. The traditional foot data collection methods can be divided into two sorts. The first is manual measurement as shown in Figure 0(a),b. Using a cloth ruler, steel ruler and other tools may lead to a deviation due to the errors in the measurement position or technique. Besides, the work efficiency and the repetition rate are relatively low, and the error between different surveyors is large. The second is the foot scanner, which uses laser scanning--the laser lines are emitted from one or more laser sources at a certain frequency. Multiple cameras are used to collect multiple frames of images from different angles to obtain foot data. However, the equipment is expensive, bulky, has poor portability and high maintenance cost in the later stages. To tackle the problems of large measurement error manual measurement and the poor convenience of foot scanners, this paper proposes a 3D model reconstruction method based on mobile phone photographs.  
Foot 3D reconstruction is different from other objects, because the overall volume of the foot is small, and the surface of the foot is uneven. Besides, the texture feature of foot skin is not obvious, which makes it difficult to establish the corresponding relationship of the same point in different images, leading to an unsatisfactory reconstruction effect. Therefore, in our experiment, the volunteer wears colored socks and stands on a magazine, so as to obtain rich texture features and distinguish the surrounding environment for better reconstruction effect. On the other hand, magazines are used as a reference for better calculation of 3D foot parameters.  
The method allows users to take more multi-view photos of the foot with a mobile phone, preferably overlapping areas, and then the images reconstruct the 3D foot model with the relevant algorithm. The experimental error of the 3D foot reconstruction method is around 1 mm compared with the manual measurement, which is close to the scanning result of the foot scanner and is also tolerable for applications such as shoe tree customization.  
The follow-up structure of the paper is as follows--Section 2 introduces the existing techniques and methods of 3D reconstruction; Section 3 describes the principle and algorithm flow of the 3D model reconstruction of the foot based on mobile phone photography; Section 4 provides experimental results and analysis; Section 5 summarizes the full text and analyzes future development trends.