Calibration marking device

Abstract

A calibration marking device includes a support having at least one wall, the at least one wall having at least one calibration pattern on the at least one wall and at least one mounting portion extending from the at least one wall. The mounting portion may be a flap extending from the at least one wall for attaching the support to a surface or net. The support may be a three-dimensional (3D) structure. The calibration marking device may have walls that can be folded into a single plane along a common edge. The calibration marking device may have a base connecting the walls, including raised tab portions configured to fit into slots in the flaps. The flaps may include openings for attaching multiple supports together by ropes configured to be fed through the openings. The calibration marking device may include brackets for mounting the supports to a surface or net by clips.

Description

Technical Field

[0001] The present disclosure relates to calibration marks for calibrating a camera, and more particularly to an apparatus for securely disposing or mounting calibration marks for calibrating a camera for tracking a moving object in a sports arena or practice field.

[0002] Systems for analyzing various characteristics of a moving object are known. In one example, the analysis of the movement of an object can be related to participation in sports, and the moving object can be part of the sport itself, such as a baseball, golf ball, tennis ball, hockey puck, cricket ball, ski, or ammunition for target shooting.

[0003] A system for tracking a moving object uses 3D metric information extracted from 2D images captured by one or more cameras. The cameras must first be calibrated for their optical and geometric properties. Camera calibration is the process of estimating the intrinsic and extrinsic camera parameters based on the observation of known physical targets. The intrinsic parameters of a camera relate to the internal shape and optical properties of the camera itself, and the extrinsic parameters measure the position and orientation of the camera relative to the world coordinate system in 3D space.

[0004] Conventional camera calibration techniques use one or more images of specially designed calibration targets or marks. The calibration target includes several easily detectable fiducial markers or features with known relative 3D positions. By fixing the world coordinate system within the calibration object, point correspondences between 3D world points and 2D image points can be established. By solving the system of equations obtained from these point correspondences, the intrinsic camera parameters and the extrinsic camera parameters can be calculated.

[0005] The most commonly used available calibration marks are typically very large and obtrusive, and thus suitable for room-sized installations for so-called "factory calibration."

[0006] However, while known calibration marks can be used in athletic fields, they are limited, mainly due to their bulky size. Currently available calibration marks cannot withstand being struck by the ball and tend to be accidentally placed in the wrong location or shifted. [Overview of the Initiative]

[0007] In one embodiment, the calibration marking device includes a support having at least one wall, at least one calibration pattern on at least one wall, and at least one mounting portion extending from at least one wall. In one embodiment of the calibration marking device, the at least one mounting portion comprises a flap extending from at least one wall configured to attach the support to a surface or net. In one embodiment of the calibration marking device, the support is a three-dimensional structure, which may be prism-shaped in one example. In one embodiment of the calibration marking device, the three-dimensional structure has a triangular prism shape of a pair of walls extending from a common edge to a pair of spaced edges opposite the common edge, each of the pair of walls having an inner surface facing each other and an outer surface facing in opposite directions, with at least one calibration pattern on at least one of the outer surfaces. In one embodiment of the calibration marking device, the pair of walls are foldable into a single plane along the common edge.

[0008] In one embodiment of the calibration marking device, the base connects to each of the opposing edges of a pair of walls. In one embodiment of the calibration marking device, the flap includes one or more slots, and the base includes one or more raised tab portions, at least one of which is configured to fit into one or more slots of the flap. In one embodiment of the calibration marking device, the flap includes an opening configured to mount multiple supports together such that the supports are spaced apart from each other. In one embodiment of the calibration marking device, a rope is configured to feed through the opening to mount the multiple supports together.

[0009] In one embodiment of the calibration marking device, at least one mounting portion includes a bracket configured to mount a support on a surface or net. In one embodiment of the calibration marking device, at least one clip is included for attaching the bracket to the support. In one embodiment of the calibration marking device, the support includes corresponding slots for receiving each of the at least one clip. In one embodiment of the calibration marking device, the bracket includes corresponding slots for receiving each of the at least one clip. In one embodiment of the calibration marking device, at least one clip is configured to attach a rope to the support. In one embodiment of the calibration marking device, at least one clip includes a body portion, a first extension extending from an edge of the body portion, and a second extension extending from an opposing edge of the body portion. In one embodiment of the calibration marking device, at least one clip further includes a resistance means configured to adjust the resistance of the clip. In one embodiment of the calibration marking device, the body portion is configured to press a rope against one surface of the support, and the first and second extensions are foldable relative to the body portion to fit into corresponding slots of the support and bracket. In one embodiment of the calibration marking device, the main body includes two walls that hold a rope between them, and the first and second extensions are foldable relative to the main body so as to fit into corresponding slots of a support and a bracket.

[0010] Further features of various embodiments, as well as their structure and operation, will be described in detail below with reference to the accompanying drawings. In the drawings, similar reference numerals indicate identical or functionally similar elements. [Brief explanation of the drawing]

[0011] [Figure 1] This is an isometric projection view of one embodiment of the calibration marking device disclosed herein. [Figure 2] This is an isometric projection view of one embodiment of the calibration marking device disclosed herein. [Figure 3]This figure shows one embodiment of a pre-folded single piece of material for forming a calibration marking device disclosed herein. [Figure 4] This is an enlarged view of an opening in one embodiment for securing a rope or cable to the calibration marking device disclosed herein. [Figure 5] This is a diagram of one embodiment of a calibration marking device disclosed herein, in which multiple marks are connected by ropes or cables. [Figure 6] This is a diagram of one embodiment of a calibration marking device disclosed herein, in which multiple marks are connected to the side of a net. [Figure 7] This is a diagram of one embodiment of a calibration marking device disclosed herein, in which multiple marks are connected to a pair of poles. [Figure 8] This is an isometric projection view of one embodiment of a calibration marking device disclosed herein, in which the marks are mounted on a bracket. [Figure 9] This is an exploded view of one embodiment of a calibration marking device for mounting to a bracket, disclosed herein. [Figure 10] This is a diagram of an embodiment of a mark clip for mounting the bracket of the calibration marking device disclosed herein. [Figure 11A] This is an isometric projection view of one embodiment of a calibration marking device disclosed herein, showing a clip for attaching a rope to a calibration mark. [Figure 11B] This is an isometric projection view of one embodiment of a calibration marking device disclosed herein, showing a clip for attaching a rope to a calibration mark. [Figure 11C] This is an isometric projection view of one embodiment of a calibration marking device disclosed herein, showing a clip for attaching a rope to a calibration mark. [Figure 12] This figure shows one embodiment of a pre-folded single-piece material for forming a clip for a calibration marking device, as disclosed herein. [Figure 13] Figure 12 is an isometric partial projection view of the clip for the calibration marking device disclosed herein.

[0012] Further features of various embodiments, as well as their structure and operation, will be described in detail below with reference to the accompanying drawings. In the drawings, similar reference numerals indicate identical or functionally similar elements. [Modes for carrying out the invention]

[0013] As shown in Figure 1, in one embodiment, the calibration marking device 10 includes a support 12 having two walls 14. However, other configurations including a single-wall support or a support with three or more walls are also possible. As shown in Figures 1 and 2, in one embodiment, a calibration pattern 16 is provided on each wall 14. However, other configurations are possible, such as when the calibration pattern 16 is provided on fewer walls than all the walls forming the support 12. In some embodiments, the calibration marking device 10 includes a support 12 having two walls 14, and the calibration pattern 16 is provided on one of the two walls 14.

[0014] In the embodiment shown in Figure 1, the calibration pattern 16 is a checkerboard pattern. However, any other suitable calibration pattern can be used. The wall 14 containing the calibration pattern 16 can be made of any material sufficient to support the calibration pattern 16. For example, suitable materials for the support wall 14 include plastics, rigid or flexible polymers, metals, and various composite materials. Polymers may include polycarbonate, acrylonitrile, butadiene, styrene (ABS), bakelite, polyethylene, polypropylene, and mixtures thereof.

[0015] As shown in Figures 1 and 2, in one embodiment, the calibration marking device 10 further includes mounting portions 18 extending from each wall 14. However, other configurations are possible, for example, in which the mounting portions 18 extend from fewer walls than all of the walls 14 of the support 12. In one embodiment, the mounting portion 18 is a flap 20 extending from the wall 14. The flap 20 may extend from one wall 14 or both walls 14. In some embodiments, the mounting portion 18 is integrated with the material forming the wall 14. In some embodiments, the mounting portion 18 is a separate piece of material connected to the wall 14. In some embodiments, the mounting portion 18 is detachable from the wall 14. In some embodiments, the flap 20 is configured to attach the support 12 to a surface or net, as described below.

[0016] In one embodiment, as shown in Figures 1 and 2, the support 12 is a three-dimensional (3D) structure having a prism shape. However, other three-dimensional (3D) shapes are also possible. The three-dimensional structure shown in Figures 1 and 2 has a triangular prism shape formed by a pair of walls 14 extending from a common edge 22 to a pair of spaced-out edges 24 opposite to the common edge 22. As shown in Figure 1, the pair of walls 14 have opposing inner surfaces 26 and opposing outer surfaces 28. The calibration pattern 16 is located on the outer surface 28.

[0017] In some embodiments, the walls of the calibration mark device can be folded from a structure in a single plane into a three-dimensional (3D) structure and then refolded into a single plane again. In one embodiment, as shown in FIG. 3, the calibration mark device 30 includes a pair of walls 32. The walls 32 are foldable from a single plane about a center line 34 to form a three-dimensional (3D) support structure such as the support 12 shown in FIG. 1. In some embodiments, the calibration mark device can be manufactured from a single piece of material where the center line 34 is formed as a living hinge. In some embodiments, the walls 32 are separate pieces of material connected by a hinge such as a pin hinge. The calibration mark device 30 having foldable walls 32 is thereby conveniently portable for easy transportation for use in different locations such as a sports arena or a training center. In some embodiments, for easy transportation and to maintain a compact state, the calibration mark device 30 may be stored in a single plane structure as shown in FIG. 3.

[0018] In some embodiments, the calibration mark device can be manufactured via die cutting followed by a folding process. In some embodiments, the calibration mark device may be manufactured by injection molding. In some embodiments, the calibration mark device manufactured by injection molding may include a living hinge. In some embodiments, the calibration pattern can be printed via ultraviolet (UV) printing or silk screen (or screen printing). In some embodiments, for long-term outdoor use, a laser etching method may be used to avoid fading of inks and dyes. In some embodiments, infrared (IR) reflective markings can be used in low-light calibration where an IR light source is used for illumination.

[0019] As shown in FIG. 3, the calibration mark device 30 includes flap portions 36 extending from both sides of the wall portion 32 on the opposite side of the center line 34. In some embodiments, the flap portion 36 may be manufactured from the same single piece of material as the wall portion 32. In some embodiments, the flap portion 36 is foldable along line 38. In some embodiments, the line 38 is formed of a living hinge. In some embodiments, the flap portion 36 is a separate piece of material connected to the wall 32 by a hinge such as a pin hinge. In some embodiments, as shown in FIG. 3, the single piece of material from which the calibration mark device is formed includes side flaps 37. The side flaps 37 are folded and are within the internal space between the walls 32 when the calibration mark device 30 is formed into a three-dimensional (3D) structure. As shown in FIG. 2, the side flaps 37 provide additional stability to maintain the calibration mark device 10 in a three-dimensional shape and help withstand the impact of the ball during use.

[0020] The calibration mark device of the present disclosure has morphological elements that enable the device to be easily transported and installed. Further, the calibration mark device of the present disclosure can be used in various environments including cages during a sports arena or training session. The ability to carry the calibration mark device of the present disclosure allows the calibration mark to be easily positioned so as not to interfere with the trajectory of the ball during play or training. Advantageously, the calibration mark device of the present disclosure can, in most cases, withstand the impact of the ball during use.

[0021] In some embodiments, the calibration mark device may include a base connected to a support. In one embodiment, as shown in FIGS. 1 and 2, the base 40 is connected to a pair of spaced edges 24 of the wall 14. In some embodiments, the base 40 may be connected to the attachment portion 18. The base 40 provides additional stability when the calibration mark device 10 is placed on the ground or attached to the side of a practice net or cage.

[0022] In one embodiment, as shown in Figure 3, the flap 36 includes one or more slots 42, and the base 40 includes one or more raised tab portions 44. The one or more raised tab portions 44 are positioned on the base 40 to fit into the slots 42 of the flap 36. As shown in Figures 1 and 2, the tab portions 44 extend through the slots 42 of both flaps 20 to maintain the three-dimensional (3D) shape of the calibration marking device 10. In some embodiments, as shown in Figure 3, the wall 32 of the calibration marking device 30 includes slots 46 in the line 38. It should be understood that the slots 46 may be located elsewhere, for example, near the line 38. As shown in the embodiment of Figure 1, the base 40 fits into the slots 46 of the wall 14, and the raised tab portions 44 are pressed against the wall 14 to add stability.

[0023] In some embodiments, the calibration marking device may be configured to mount multiple support structures together such that multiple supports are spaced apart in a row from one another. In one embodiment, as shown in Figure 3, the flap 36 includes an opening 48 configured to receive a rope, cable, or other similar structure for mounting multiple supports together. In some embodiments, as shown in Figure 3, a pair of openings 48 are provided at spaced-apart positions on the flap 36. It should be understood that other configurations of openings, such as a single opening or multiple openings, may also be used. In one embodiment, as shown in the enlarged view of the opening 48 in Figure 4, the opening 48 has two circular sections 50 and a central toothed section 52. A rope or cable 54 is fed through the two circular sections 50 and arranged alternately through the teeth of the toothed section 52. In one embodiment, as shown in Figure 5, multiple supports 12 are mounted together using two ropes or cables 54 fed through the opening 48 of the flap 36. In some embodiments, ropes, cables, or other similar structures for attaching multiple supports together may be colored or marked like a ruler so that the spacing between supports can be easily adjusted and the distance can be immediately understood. In one embodiment, instead of an opening 48, a toothed cut is provided in the flap 36 so that the rope or cable 54 cannot be fed through when no force is applied to the toothed cut. However, other shapes, including straight or wavy shapes, are also possible. An opening is formed in the toothed cut only when one of the opposing sides is pressed, and then the rope or cable can be fed through the opening. Thus, the toothed cut can open when force is applied and close when no force is applied. In some embodiments, the “closed” and “open” configurations of the cut may be related to the flexibility of the material used to form the flap.

[0024] As shown in Figure 5, the calibration marks can be easily positioned on the ground of a sports field by connecting multiple calibration mark support structures 12 together. The rope or cable 54 can be secured to the ground using any suitable means such as tent pegs, nails, or clamps. In some embodiments, for use in low-light conditions, the calibration mark device may further include one or more lights, for example, at the center of the calibration mark device. Furthermore, since the position of each support structure 12 is adjustable on the rope or cable 54, the calibration marks can be used to calibrate sports object tracking equipment or launch monitor cameras positioned near the ground surface where round lines, field boundaries, home plates, etc., are not visible. In some embodiments, additional ropes, cables, or other similar structures may be added to specific positions of the calibration mark device so that the calibration mark device can be raised, lowered, or retracted. In some embodiments, the specific positions may be along the top of the calibration mark device.

[0025] Furthermore, by feeding a rope or cable 54 through the opening 48 of the flap 36, one or more calibration marks can be easily attached to the side wall of the practice cage 56 shown in Figure 6, using the calibration mark support structure 12 shown in Figure 5. Any suitable means, such as clips or clamps, can be used to attach the rope or cable 54 to the cage 56. Alternatively, the calibration mark support structure 12 may be individually attached directly to the net by fitting the net into the opening 48, similar to the method of attaching the rope 54 shown in Figure 4. In some embodiments, the rope or cable 54 connecting one or more calibration mark support structures 12 can also be attached to a pair of poles 58 shown in Figure 7. Tension can be applied to the rope 54 between the poles 58 using a bowline knot 60 or a hammock knot 62. By attaching one or more calibration mark support structures 12 attached to the rope or cable 54 to a pair of poles 58, as shown in Figure 7, a structure is provided that can be positioned for calibrating a camera when using a small practice net instead of a cage. In some embodiments, the rope or cable 54 may be colored or marked like a ruler so that the spacing between supports can be easily adjusted and the distance can be immediately understood.

[0026] In some embodiments, the mounting portion of the calibration marking device is a bracket. As shown in Figure 8, the calibration marking device 70 includes a bracket 72 configured to mount a support 74 on a surface or net. In some embodiments, the calibration marking device 70 is a two-dimensional (2D) structure. In some embodiments, the calibration marking device 70 includes one or more clips 76 or other suitable equipment for attaching the bracket 72 to the support 74. In some embodiments, as shown in Figure 8, the clips 76 are configured to attach a rope 82 to the outside of the support 74. Figure 9 is an exploded view of one embodiment of the bracket 72, support 74, rope 82, and clips 76. In some embodiments, as shown in Figure 9, the support 74 includes corresponding slots 80 for receiving the clips 76. The bracket 72 includes corresponding slots 80 for receiving each of the clips 76. In some embodiments, the slots 80 are configured to receive the clips 76 in a folded configuration.

[0027] In some embodiments, as shown in Figure 10, the clip 76 comprises a body 84, a pair of extensions 86 extending from one edge of the body 84, and a pair of extensions 88 extending from the opposite edge of the body 84. The body 84 presses the rope 82 against the support 74, and the extensions 86 and 88 engage through slots 80 and fold on the underside of the support 74 to tighten the rope 82 against the support 74. In some embodiments, the clip 76 may include resistance means for adjusting the resistance of the rope 82 against the support 74. Figure 10 shows one embodiment of resistance means in which the clip 76 includes a pair of intermediate extensions 90. When the intermediate extensions 90 are folded inward toward the body 84, they press the rope 82 to adjust the resistance of the clip 76. Other forms of means for adjusting the resistance of the clip 76 against the support 74 are contemplated in this disclosure.

[0028] Figures 11A to 11C show alternative embodiments of the clip 92. In this example, Figure 11A shows a top view of the calibration marking device 100, where the clip 92 is attached to the support 104, and a channel is formed by the clip 92 when folded. In some embodiments, the formed channel allows the rope 98 to pass through. Figure 11B shows a side view of the calibration marking device 100, where the clip 92 is also attached to the bracket 72. In some embodiments, the rope 98 passes through the channel formed by the folded clip 92. Figure 11C shows a bottom view of the calibration marking device 100, where the clip 92 is attached to the bracket 72 and the support 104, and the pair of extensions 106, 108 rest on the bracket 72 to provide resistance, thereby securing the rope and preventing the clip 92 from detaching from the bracket 72 and the support 104. The main body 94 integrates to conceal the rope 98 from view. Figure 12 shows the clip 92 manufactured in a substantially flat form in an unfolded configuration. Figure 13 shows a partial view of the clip 92 with various parts folded for use. The middle section 91 of the clip 92 includes a channel for holding a rope between them, and the channel is formed by a body section 94 that folds around a line between the middle section 91 and extensions 106 and 108. The clip 92 includes a first pair of extensions 106 and a second pair of extensions 108. The extensions 106 and 108 are foldable relative to the body section 94 to fit into corresponding slots (not shown) in the support 104 and bracket 72. The wall section 96 is foldable for holding a rope 98. In some embodiments, the body section 94 is dimensioned to be approximately the same length as the opening so that the clip 92 fits into the opening in the folded configuration (not shown). Extensions 106 and 108 prevent the clip from escaping through the opening because they are on a different plane from the opening. Furthermore, when the wall 96 is folded into the central section 91, the free space within the channel is reduced, thus providing additional resistance to the rope.

[0029] While the present invention has been specifically illustrated and described in relation to its preferred embodiments, those skilled in the art will understand that the aforementioned and other modifications to the form and details can be made without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the exact forms and details described and illustrated, but is intended to fall within the scope of the appended claims.

Claims

1. A support having at least one wall and at least one calibration pattern of the at least one wall, A calibration marking device comprising at least one mounting portion extending from the at least one wall.

2. The calibration marking device according to claim 1, wherein the at least one mounting portion comprises a flap extending from the at least one wall, the flap being configured to attach the support to a surface or net.

3. The calibration marking device according to claim 1, wherein the support is a three-dimensional structure.

4. The calibration marking device according to claim 3, wherein the three-dimensional structure has a prismatic shape.

5. The calibration marking device according to claim 3, wherein the three-dimensional structure has a triangular prism shape with a pair of walls extending from a common edge to a pair of spaced-apart edges opposite the common edge, each of the pair of walls having an inner surface facing each other and an outer surface facing the opposite side, and the at least one calibration pattern is located on at least one of the outer surfaces.

6. The calibration marking device according to claim 5, wherein the pair of walls are foldable into a single plane along the common edge.

7. The calibration marking device according to claim 5, further comprising a base connected to each of the opposing edges of the pair of walls.

8. The calibration marking device according to claim 7, wherein the at least one mounting portion comprises a flap extending from each of the opposing edges of the pair of walls, the flap being configured to attach the support to a surface or net.

9. Calibration marking device according to claim 8, wherein the flap includes one or more slots, and the base includes one or more raised tab portions, and at least one raised tab portion is configured to fit into the one or more slots of the flap.

10. The calibration marking device according to claim 8, wherein the flap includes an opening configured to attach the plurality of supports together such that the plurality of supports are spaced apart from each other.

11. The calibration marking device according to claim 10, further comprising a rope configured to be fed through the opening to attach the plurality of supports together.

12. The calibration mark according to claim 1, wherein the at least one mounting portion comprises a bracket configured to mount the support on a surface or net.

13. The calibration marking device according to claim 12, further comprising at least one clip for attaching the bracket to the support.

14. The calibration marking device according to claim 13, wherein the support includes a corresponding slot for receiving each of the at least one clip.

15. The calibration marking device according to claim 14, wherein the bracket includes corresponding slots for receiving each of the at least one clips.

16. The calibration marking device according to claim 15, wherein the at least one clip is configured to attach a rope to the support.

17. The calibration marking device according to claim 16, wherein the at least one clip comprises a main body, a first extension extending from an edge of the main body, and a second extension extending from an opposing edge of the main body.

18. The calibration marking device according to claim 17, wherein the at least one clip further comprises a resistive means configured to adjust the resistance of the clip.

19. The calibration marking device according to claim 17, wherein the main body is configured to press the rope against one surface of the support, and the first extension and the second extension are foldable relative to the main body so as to fit into the corresponding slots of the support and the bracket.

20. Calibration marking device according to claim 17, wherein the main body comprises two walls that hold the rope between them, and the first extension and the second extension are foldable relative to the main body so as to fit into the corresponding slots of the support and the bracket.

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