EP2088890A1

EP2088890A1 - Three-dimensional scanning of feet

Info

Publication number: EP2088890A1
Application number: EP07835574A
Authority: EP
Inventors: Matija Jezersek
Original assignee: Alpina Tovarna Obutve doo
Current assignee: Alpina Tovarna Obutve doo
Priority date: 2006-11-07
Filing date: 2007-11-07
Publication date: 2009-08-19
Also published as: SI22424A; WO2008057056A1

Abstract

The invention consists of a scanning device and a procedure enabling a three-dimensional body surface scan. It is especially appropriate for scanning feet in order to produce fitting shoe lasts and consequently comfortable shoes. This method is particularly suitable for making ski boots, which need to fit their individual owners' feet. The 3D body surface scanner, also very suitable for scanning feet takes advantage of the feet scanning principle based on the rotation movement and on the rotation of the triangular module comprising two cameras (7, 8) and a laser projector (9), a main and a step-on platform (11), and a mechanism enabling circulation and rotation of the measuring module.

Description

THREE-DIMENSIONAL SCANNING OF FEET

The invention consists of a scanning device and a procedure enabling a three-dimensional body surface scan, especially suitable for scanning feet in order to produce fitting shoe lasts and consequently comfortable shoes. This method is particularly suitable for making ski boots, which need to fit their individual owners' feet. The invention falls into the class G 01 B 11/24 of the International Patent Classification.

The solution of a technical problem that this invention offers lies in the construction of the device itself. It primarily enables simultaneous scanning of both feet in their normal and relaxed position, an accurate scan of the toes and the sole in addition to a quick and low-cost performance.

There are several devices for measuring body surfaces of irregular shapes. The document EP 0 422 946 patents a device for measuring bodies with irregular shapes, such as shoe lasts. The device scans the shoe last surface point by point by rotating around the last and simultaneously moving along its main axis. The measuring module of the device is put together of two CCD line cameras symmetrically arranged according to the point laser projector. The document reveals that the device is primarily designed to scan shoe lasts, each one separately. The scanning procedure is time consuming an as such inappropriate for scanning live and moving parts like feet.

The solution described in the patent document EP 0 671 679 is very similar to the previously mentioned regarding its functioning principle and purpose. The only difference is that this patent also makes it possible to rotate the measuring module around two perpendicular axes, besides the rotational and translational movement along the last.

The patent document PCT/US97/00985 (WO97/27451) describes a device very similar to the afore-mentioned but this one can be used to scan the shape of the feet. The orbit axis of the measuring module has to coincide with the longitudinal axis of the foot (heel-middle toe). The surface of every foot is scanned point by point.

The device described in the patent document PCT/EP97/05850

(WO98/18386) is only used for measuring the shape of the feet. The device is able to measure only one foot at the time. The foot needs to be inserted into the opening of the platform. The measuring module mounted under the platform scans the foot by rotating for 360°. The measuring module works according to laser triangulation, where lines scan the surface of the foot. It comprises a video camera and a laser projecting a laser plane. It takes only a moment to make a cross section of the foot.

The entire foot surface is reconstructed based on the scanned profiles.

This device is unpractical, because the foot needs to be inserted into the opening and because of switching the feet. Another weak point is that the foot is an unnatural position during the measurement since the other foot is placed somewhat higher.

The device from the patent document US 2004/0184040 functions according to the photogrammetry principle. The person being scanned steps on the platform, which has photogrammetic landmarks that help the measuring module (consisting from a camera and lights) to orientate in the room in order for the camera to record these landmarks and the foot. A special elastic layer with photogrammetic landmarks drawn on it should beforehand cover the foot or any measured object. The measuring module then rotates around the foot making a full circle (360°). The weak point of this innovation is that prior to the measurement the subject needs to put on special socks - that is time consuming, non-economic, imprecise (due to enlarging the foot) and unhygienic. Another flaw lies in the measuring principle itself and the related recognition of the photogrammetic patterns. It is well known that this technique demands a lot of processor capacity and that it is sensitive about possible disturbances such as foot movement or inadequate lighting in the measurement room.

Considering the described inventions none seems to solve the technical problem to a satisfying degree. The 3D body surface scanner, also very suitable for scanning feet takes advantage of the feet scanning principle based on the rotation movement and on the rotation of the triangular module comprising two cameras and a laser projector, a main and step-on platform, and a mechanism enabling circulation and rotation of the measuring module.

The three-dimensional body surface scan, particularly suitable for scanning feet shall be explained in detail by an example and the following corresponding figures:

Figure 1 The body surface scanner in axonometric view; Figure 2 The body surface scanner from a lateral view; Figures 3a, b, c, d The series of movements during the body surface scan;

Figure 4 Schematic depiction of the shadow during scanning; Figure 5 A functioning scheme of the laser measuring module with one camera and a laser line projector;

Figure 6 A functioning scheme of the laser measuring module with two cameras and a laser line projector;

Figure 7a Block scheme of the body surface scanner; Figure 7b Block scheme of the measuring module of the body surface scanner.

The 3D body surface scanner, which is also very appropriate for scanning feet, functions according to the principle of circulation and rotation of the laser triangular measuring module. The construction of the scanner is shown on Figures 1 and 2, the block scheme of the device and of the measuring module are shown on Figures 7a and 7b. Figures 3a, b, c, d will help explain the functioning of the device. The procedure of the body surface scan, which is particularly suitable for scanning feet, consists of the following series of movements (when scanning clockwise):

The second axis B starts to rotate (Figure 3a). Once the measuring module reaches the angle at which the laser plane intersects with the first rotation axis A, this axis stops. Then, measuring module 1 starts to rotate around the first axis A (Figure 3b). The rotation around the first axis A stops and the rotation of the measuring module 1 around the second axis B commences (Figure 3c). The rotation around the second axis B finishes (Figure 3d). The second axis B is added because of the shadow and the related non-scanning of the inner side of the foot, when the other foot is placed between the measuring module 1 and the surface (Figure 4). Furthermore, the coverage is improved due to the usage of two cameras 7,8 that are symmetrically mounted according to the laser plane (Figure 6). Measuring module 1 , which is based on the principle of laser triangulation by lighting the surface with lines, consists of a laser line projector 9 and at least one camera 7. The laser line projector 9 illuminates the scanned body with a light plane. The intersection of the plane and the surface of the scanned body is called an intersection curve. A camera captures the illuminated surface from another optical angle. The light is dispersed at the intersection curves and a portion of it is mapped onto the sensor surface of the camera through the lens of camera 7. The shift of the scanned surface causes a relative change of the position of the intersection curve image on the camera. The image enables us to determine coordinates of the intersection curve, which shall be the basis for calculating 3D point coordinates on the surface of the measured body by means of data about camera 7, the laser line projector 9 and their mutual position. Figure 5 depicts the functioning principle of the laser measuring module with one camera 7.

If you are about to measure complex surfaces, it makes sense to use the measuring module and two cameras. The coverage of the measured surface is thus improved (Figure 6). Figure 7a shows a block scheme of the three-dimensional body surface scanning device. It comprises a measuring module 1 , a rotating mechanism 2,2' for moving measuring module 1 , a power unit 3, a computer 4, a monitor 5 and a keyboard 6. Measuring module 1 consists of two cameras 7 and 8 and a laser line projector 9. The computer 4 has a two-way connection to the measuring module 1 and through the RS232 interface 10 the rotation mechanism 2,2' for moving the measuring module 1 is connected. On the opposite site, monitor 5 and keyboard 6 are connected to the computer 4. When the person scanned steps onto platform 11 , the device makes a three-dimensional foot scan. The operator or the scanned person respectively, launches the scan by means of the keyboard 6 or in another computer recognizable way (by voice command, by a specific key, touch screen etc.) The computer 4 sends a signal through the RS232 interface 10 to the control electronics of the rotation mechanism 2,2' to start movements as they are depicted in Figures 3a, b, c, d. The control electronics of the rotation mechanism 2,2' sends signals through the interface RS232 to the computer about when certain movement phases actually begin and finish. The computer 4 only captures the image from the cameras when the measuring module moves (rotates) evenly, that is in periods that are marked by the previously mentioned signals of the control electronics. After all three movements are finished, the captured data is processed. The result is in phase one a cloud of three-dimensional points that mark the surface of both feet. The computer analyses these points and specifies significant dimensions, such as length, height, width and breadth on every cross section of both feet. The results of this analysis are then graphically displayed on monitor 5, printed out and saved into a database. The measuring procedure is now complete. If this scan should take place in a store, the computer algorithm may continue and chose a shoe that fits the customer's foot best. The advantages of this device over other similar devices are due to the specific movement phases of the measuring module and the construction of the device as follows:

- The toe and heel area are measured very precisely, because the measuring direction is almost perpendicular to the toe or heel surface,

- Both feet are measured simultaneously. The person scanned does not need to hop from one foot to the other and the most important thing; both feet are in a correct and relaxed position. Furthermore, the measuring time is extremely short,

- Simple and low-cost performance.

Claims

1. A three-dimensional body surface scanning device comprising a measuring module (1), a rotation mechanism (2.2¹) for moving the measuring module (1), a power unit (3), a computer (4), a monitor (5) and a keyboard (6).

2. A three-dimensional body surface scanning device as recited in Claim 1 , the measuring module (1) comprising at least one camera (7) and a laser line projector (9).

3. A three-dimensional body surface scanning device, as recited in Claim 1 , the measuring module (1) comprising two cameras (7, 8) and a laser line projector (9).

4. A three-dimensional body surface scanning device, the measuring process begins with the rotation of the second axis (B), whilst measuring module (1) is initially turned 45° towards the first rotation axis (A). When the measuring module (1) reaches the angle, at which the light plane intersects with the first rotation axis

(A), this axis comes to a stop. The measuring module (1) starts rotating around the first axis (A) and when it stops it starts rotating around the second rotation axis (B). This movement stops, when the measuring module (1) reaches an approximately 45° angle towards the first rotation axis (A).