From 3D foot scans to footwear designing & production

Transcription

1 From 3D foot scans to footwear designing & production E. Piperi1, L. M. Galantucci2, J. Kaçani1, E. Shehi3 and T. Spahiu3 1 Faculty of Mechanical Engineering, Department of Production and Management in Polytechnic University of Tirana, epiperi@fim.edu.al, Tirana 2 3 Dipartimento di Meccanica, Matematica e Management Politecnico di Bari, Italy Faculty of Mechanical Engineering, Textile and Fashion Department in Polytechnic University of Tirana Keywords: 3D foot scans, footwear designing, custom shoes, reverse engineering, 3D printing. Abstract 3D scanning is a potential technology for creating individualized products. It is used in various fields such as medicine, clothing manufacture, footwear manufacture, etc. The last mentioned field has gained a growing interest in recent years. The foot is regarded as an important part of human body. Footwear fit, is one of the main factors for consumer on purchasing shoes in the daily life decisions. Designing footwear is a very complex process. Traditional footwear design begins with a plan to sketch patterns and designs in scale drawings. The paper sketches are done by hand, or on computer-aided software, but it can be a mix of both technologies. In this paper we are going to present a full cycle of footwear production, starting from 3D foot scanning, to 3D shoes designing, 2D patterns extraction, till the production of the custom shoes. The system, explained in these work will give the opportunity to individual clients to produce their own shoes prototype. We are going to use the 3D printing technology to produce custom shoes. These will help people, which have feet problems with standard shoes available in the market creating their own shoe last. Also, it will be possible to create sample prototypes and refining the same for both functionality and aesthetics. 1 Introduction Footwear can be defined as a garment worn by feet. The main scope is protecting the feet of the wearer, which is a very important part of the human being. The foot is regarded as the second heart of the human beings in traditional Chinese medicine, transmitting and attenuating the impact forces between the ground and the human skeletal system [1]. Feet have a rough time of it; they carry us the equivalent of five times around the earth in an average lifetime, yet we give them less attention than they deserve and we rarely wear the best shoes for our feet [2]. The main factors indicating the purchasing decision of consumers are two: footwear appearance and footwear fit. Fit is one of the most important functional aspects in footwear comfort and together with appearance and price, is one of the most important considerations for users when purchasing new footwear [3]. The foot provides a crucial contribution to the balance and stability of the musculoskeletal system. Foot problems are common among a wide group of people, ranging from simple disorders through to complex diseases and joint deformities [4]. 1

2 Footwear shape and dimensions are influenced by the last s shape and dimensions. The most important component of the shoemaking is a shoe last, a 3D mold around which a shoe is made. A shoe last is closely related to the foot and its design is based on many factors such as the foot shape/size, comfort parameters, shoe fashion/style, type of construction, etc. [5]. Manufacturers attempt to design and develop footwear so that provide a covering for the foot while exhibiting fashion or style. Product performance on the other hand, can be broadly evaluated based on its function, form, and fit. It is well known that fit or product compatibility is necessary for a person to experience comfort, safety and satisfaction during use [6]. Various methods of designing and manufacturing software, along with fashion trends do not always respect structural and functional requirements of the feet. Because of this, in time, muscles, bones and joints are overstretched, resulting in a change of morphological and structural characteristics of the feet [7]. 2 3D technology 3D technology has gained a lot of importance in recent years. It is used in various fields of application, such as medicine, science, engineering, military, entertainment and now in the apparel industry. In the world of fashion, 3D technology offer the potential for creating made-tomeasure apparel meaning clothing and footwear. The human fit are complex 3D objects having a wide diversity in their shapes depending upon locality, age, sex, etc. [8]. The use of 3D scanning technology to produce digitized representations of parts of the human anatomy has the potential to help change the way e wide range of products are designed and fabricated [9]. There are a lot of applications of 3D scanning technology for digitizing different part of human body. Their scope it is more than product interaction. With the research field shifting to more information and better accuracy, 3D scanning has quickly become the standard in capturing foot geometry. Analysis into the capability of 3D scanning for foot modeling showed that 3D scans were very reliable and repeatable [10]. 3D printing technology is widely used recently for manufacturing of footwear products. 3D printing is a form of additive manufacturing (AM) technology where a three dimensional object is created by laying down successive layers of materials. Additive manufacturing (AM), also known as 3D printing, rapid prototyping or solid freeform manufacture. Additive manufacturing is an umbrella term which covers a range of technologies that utilize layer manufacturing to fabricate items. 3 Methodology Designing footwear products is a complex process. Designing the footwear on the scanned foot, meaning the custom last will provide a good fit. The scope of our work was implementation of a low cost structured light scanning system for 3D foot scan. In Error! Reference source not found. are shown the main steps used in these work. They include: 1. 3D foot scanning, 2. Creation of the 3D foot model, 3. Converting in 3D foot last, 4. Comparing the converted 3D foot last with 3D scanned foot model, 5. Shoes design, 2

3 6. Different possibilities for producing custom shoes Fig 1. From 3D foot scans to footwear designing & production 4 Experimental work 4.1 Structured light scanning system The 3D shape of the foot used for designing custom footwear was taken from the 3D Structured Light Scanning Systems David Laser-Scan. The system created for the foot scan is based on low cost 3D structured light system (SLS) based on the software platform of the DAVID Vision Systems GmbH s DAVID-Laser Scanner. On the shelf hardware and equipment s as light projector, web camera and also open source software can be used for 3D scanning systems [11]. The schematic view of the system is show in Fig 3. Schematic view of foot Structured light scanning system SLS use a video projector instead of the laser. The video projector Acer X110 (1920x1080 pixels) was used to project a number of stripe patterns onto the object. To have a higher resolution of single scans, the pattern parameter used was Quality with 58 number of patterns. The camera used has a CMOS sensor model ueye UI-1480-C (5MPixel, 6f/s, CE class A of regulation) and the optic lenses used is Fujinon 1: 1.2/6 mm DF6HA 1B. Camera and structured light emitter (projector) calibration is based on triangulation calculation. The field of view of the sensor is fixed by maintaining constant the D distance. This range will be always in the depth of field of the sensor. Using conventional geometry, the field of view of the sensor is [12]: 3

4 Where: P 2 tan 1 D f Eq. (1) f- is the focal length of the lens D- is the triangulation base [(A-B)=const, Fig. 2] P- is the dimension of the CMOS Fig 2. Setup of the scanning systems To improve measurement accuracy, the baseline (D) can be increased, or a larger sensor (P) should be used. These modifications sometimes are not possible, due to the optical system setup, in which the stability of the system decreases with the increase of (D), and for the shadow effect (self-occlusion problems increase with (D)). Based on the deformations of the stripe patterns in these images, DAVID will compute a precise 3D point cloud of the object surface. Fig 3. Schematic view of foot Structured light scanning system 4

5 After different tests has done, the best scans quality occurs when triangulation angle was from 15 to 20 degree. For an optimal 3D fuse foot scanned object, the minimum number of single scans was 6 scans [13]. The total time of single acquisition was 1.3 min with a 5Mp of resolution. Regarding the hardware used in these work (a workstation laptop Fujitsu H 700 series) the frame per seconds (fps) parameters ranged from 2 to 6 fps. In Fig 4. Scanning process: a) setup; (b, c) calibration succeeded; (d, e) during scans; f) fusion of single step scans.are shown the steps needed for the reverse process, from optical setup till the creation of the 3D foot scan model. Fig 4. Scanning process: a) setup; (b, c) calibration succeeded; (d, e) during scans; f) fusion of single step scans D data analyzing (Geomagic studio ) In the reversed engineering processes, especially in the 3D scanning processes there will be always some imperfection during data capture. Even in the most advanced commercial 3D scanners a big effort is made by software developers to include the data clean-up process. David software include data manipulation, however, to perform deep analyze of our scans we used Geomagic Studio software [14]. The workflow (Fig 5. Workflow from 3D foot scanning to custom shoes design) in this paper will return twice to data manipulation by Geomagic. The first part will include data manipulation as fill holes, surface smoothness, scans overlap, spike etc. These procedures will help for better last identification in the following procedure (Fig 6). 5

6 Shoe Maker software Data manipulation (Geomagic Studio) Scanning process (VIVID 910; DAVID Laser-Scan) 3D scanning workflow for costum shoes design Hardware setup Calibration of the system 3D scans and creation of different point clouds Is the texture needed? No Perform merge/align of scans Clean up data from scanning Fuse and save 3D object (.obj;.stl...) Yes Scan the texture Inspection of data scans Export the cleaned 3D foot Creation of different planes dimensions Compare last created with scanned foot Are the comparison data acceptable? YES Export and save dhe data NO Import the 3D scanned foot Defining the points needed for last identification Export the last created for analyze Shoe designed on personalized last Prepare the designed model for production technology Production technology? CAD/ CAM Export dxf pattern configuration 3D printing Export and save as STL file Fig 5. Workflow from 3D foot scanning to custom shoes design Fig 6. Scan data manipulation in Geomagic Studio software 5 Last identification and custom shoes design After modification and optimization of data scan, our 3D foot model is ready for last converting and custom shoes design. The software used for these reason is Shoe Maker 2014 [15]. The steps followed for the last identification are shown in Fig 7. The program permit to import a STL file for last identification wizard. After different point and curves identification are selected the final attribution of last as: standard, size group and size need to be specified. 6

7 Flattened last (2D) and 3D last will show up if everything was done correctly. To check the error occurred by the last identification wizard we will compare step 1 with step7 (Fig 7) back in Geomagic software. These procedure will be shown in coming sections of these work. Fig 7. Last identification from 3D foot model 5.1 Shoes design After the confirmation from data comparison (see coming section) that the converting procedure of last wizard, give accepted deviations between 3D foot scan and last converted (step 7, Fig 7) everything is ready for she design. We will use the same software Shoe Maker for shoes design. We designed a pump shoes model. The software is user friendly and easy to use for everyone. The main steps for designing the custom shoes, are shortly presented in Fig 8. Fig 8. The process of pump shoes model designing till the exporting of the shoes pattern 7

8 In Fig 8, step 6 show the 3D file exported and being ready for 3D production, meanwhile, step 7 show the 2D pattern extraction for custom shoes production. 6 3D data comparison In this section we are going to show the data comparison between 3D foot scanned versus 3D last converted. This analyze is needed to check the errors occurred during conversion process of the last. As shown by the results () generated from 3D Comparison Results, the value of standard deviation is 1.14 mm and the RMS error is 1.45 mm. These low values show that, the last identification wizard has been successfully and the 3D last converted represent the real scanned foot. Table 1. Comparison result I Reference Model Test Model No. of Data Points scans Tolerance Type Units Foot_converted_right 3D scan Fusion Result D Deviation mm Max. Critical Min. Critical Standard Deviation 1.14 Average Deviation / RMS error 1.45 Fig 9. 3D comparison results I 7 Conclusions Designing footwear is a very complex process. The work presented in these paper showed a full cycle of footwear production, starting from 3D foot scanning, to 3D shoes designing, 2D patterns extraction, till the production of the custom shoes. The implementation of different software/hardware (part of CAD/CAM Laboratory in Faculty of Mechanical Engineering in Tirane) is very crucial in the realization of custom shoes design. Different technologies can be applied after shoes designing as 3D printing (exporting as STL file), traditional ones (exporting as 2D pattern file) for made to measure shoes. These will help people, which have feet problems with standard shoes available in the market creating their own shoe last. Also, it will be possible to create sample prototypes and refining the same for both functionality and aesthetics. 8

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