DE102009059797A1 - Optical marker and object detection device - Google Patents

Abstract

Optical marker (1), in particular of an augmented reality system, with a code pattern made up of differently reflecting surfaces with a reflective layer (12) over which a masking layer (5) lies, which has recesses (9) for generating the code pattern, and an object detection device with a Image capture device and such an optical marker (1). The reflective layer (12) can comprise a retroreflective layer (3) and / or an IR filter film (4).

Description

The invention relates to an optical marker having a code pattern of differently reflecting surfaces and to an object detection device having an image capture device and an optical marker.

Optical markers can be used as part of a tracking or tracing process. Here, the marker is attached to an object, whereby it is recognizable, for example, in terms of nature, position and movement for an image capture system.

Optical markers can also be used in augmented reality systems. In augmented reality systems, virtual image content created on the computer is superimposed into real image content. In this case, tracking processes can also be used to positionally overlay 3D content with reality. For this purpose, a camera can record the reality, in which case the position and orientation of the camera relative to the object or in space can be determined, for example, by means of the optical markers visible in the scene.

The optical markers can thus be used to be arranged on individual objects, thus making the marked object detectable. By means of the marker and the corresponding code pattern, the type, the position and / or the orientation of the marked object in space can be detected. In an analogous manner, the position in the orientation of the image capture device in space can also be detected, then the mark on a still object in space at a predetermined position is arranged.

The code pattern on the marker may, for example, represent an identification code which is coded, for example, via a matrix code. The optical marker tracking system detects in the image stream provided by the camera these optical markers and calculates the position and rotation (pose) of the camera relative to the markers. Each marker can form its own coordinate system. Later, virtually generated 2D or 3D geometries can be bound to these coordinate systems.

There are known markers that carry a geometric code pattern, such as a checkered pattern or other geometric shapes, such as crosses. The flat markers, for example made of paper, have two differently reflecting surfaces, whereby the code pattern is formed. As a rule, a distinction is made according to the color, whereby a black and white combination of the code pattern is frequently present.

The DE 10 2004 046 144 A1 describes an augmented reality system in which a space is detected by means of a camera, wherein a flat marker with a geometric code pattern (cross) with differently reflecting surfaces is arranged on a wall as an object of the space to be detected.

The invention has for its object to provide an optical marker with a high visibility in a simple manufacturing process.

The invention solves the problem with the features of claim 1. Advantageous developments are part of the dependent claims.

The optical marker according to the invention has a reflection layer over which lies a masking layer which has recesses for generating the code pattern.

Due to the multi-layer structure, the recognizability of the marker can be increased since the individual layers can be formed from different materials with different reflection properties. At the same time, the preparation of the marker can be carried out in a simple manner, since the layers need only be arranged one above the other, for example by gluing.

To generate the code pattern is the masking layer, which is provided with recesses so that the underlying reflective layer is visible to the outside.

Preferably, the reflective layer comprises a retroreflective sheet, in particular a retroreflective sheet. Such a retroreflective sheet reflects incident light substantially in the direction from which it has fallen. This is advantageous so that a light source can be arranged in the spatial vicinity of an image capture device with a coupled light source, so that the image capture device recognizes a bright reflection layer. Thus, most of the light reflected from the retroreflective sheet is directed back to the image capture device where a high-contrast image can be captured. A retroreflective sheeting is used, for example, in U.S. Pat DE 696 28 766 T2 described.

Further preferably, the reflective layer comprises an infrared (IR) filter which is substantially impermeable in the visible region and permeable in the infrared region. The infrared Filter may preferably be foil-shaped, in particular shiny, designed.

When using an infrared filter, it makes sense to use an image capture device in the infrared range, such as an infrared camera. The advantage here is that the object and the marker need not be illuminated in the visible range but only in the infrared range. As a result, an independence from the ambient light and from radiating in the visible range, possibly interfering light sources can be achieved.

Most preferably, the reflective layer comprises a retroreflective sheet and an IR filter with the IR filter disposed between the masking layer and the retroreflective sheet. Thus, the retroreflective sheet is not perceived by a viewer because the visible light is not transmitted by the IR filter. For an infrared camera, however, the retroreflective layer is detectable.

In order to increase the recognizability, the masking layer should thus reflect less light in the evaluated region, in particular in the IR region, than the reflection layer. Particularly preferably, the masking layer has a matte surface, so that the recognizability of the markers can be increased even under difficult lighting conditions with interfering light sources.

The mask of the matt material can thus cover the reflective reflective layer, which is particularly advantageous when a retroreflective layer and / or an infrared filter layer are used, since the latter is usually reflective or shiny, so that the matte masking can be achieved an increased contrast. As a result, less light is reflected by the masking layer than by the reflection layer, whereby the code pattern is generated.

The preferred structure can achieve increased visibility, since it can be prevented, for example, that reflections of a disturbing light source make the pattern unreadable: The matt material of the masking layer can hardly mirror, so that the disturbing light source can not exert any influence here. In the case of the retroreflective layer, on the other hand, a maximum brightness is achieved anyway, so that possible disturbing reflections of a light source in the retroreflection are lost.

By suitable selection of reflection layer and masking layer, it can be achieved that the two layers have the same color in the visible range. It is particularly advantageous if the masking layer and the reflection layer are gray and / or black. Due to the fact that the two layers have the same color, the code pattern in the visible region is essentially not recognizable. The code pattern of the marker which disturbs the impression of an object can thus be avoided.

Thus, the appearance of the tracked object is hardly affected by the preferred marker. There is no visual restlessness due to the unusual recognition pattern of the marker.

To obtain sufficient stability of the marker, the reflective layer can be carried by a carrier layer. About the carrier layer, the marker can be arranged for example by means of an adhesive to an object. The carrier layer can be rigid or flexible.

An object detection device according to the invention has an image capture device, for example a camera, and an already described optical marker, which can be arranged on an object to be detected.

Particularly preferably, the image capture device comprises an infrared camera (IR camera). Further preferably, the object detection device further comprises an infrared radiator (IR radiator). Particularly preferably, the infrared radiator is arranged to the image capture device such that it radiates substantially in the direction of the viewing direction of the image capture device. This can be achieved in an advantageous manner in that the infrared radiator is coupled to the image capture device, in particular rigidly coupled, it being possible for example to arrange it directly on the image capture device.

An augmented reality system according to the invention has an object detection device already described, a computer for generating the virtual image contents of the augmented reality and a monitor. The computer can in this case be connected to the image capture device.

A preferred embodiment of the invention will be described with reference to 1 to 3 described. Show it:

1 an optical marker;

2 after the optical marker 1 in an exploded view; and

3 an object detection device.

The 1 and 2 show an optical marker 1 with a geometric code pattern C. The marker 1 is designed essentially flat.

The 2 shows the plate-shaped marker 1 in an exploded view. It comprises a carrier layer 2 made of a flexible material, such as plastic. On the carrier layer 2 is a foil-shaped retroreflective layer 3 arranged.

On the passive, retroreflective sheeting 3 is an IR filter foil 4 arranged, which consists of a black, shiny material. The infra-red filter sheet is transmissive to infrared light, but substantially impermeable in the visible region, so that a viewer has substantially no reflections of the retroreflective sheeting 3 recognizes.

On the infrared filter foil 4 is a masking layer 5 arranged, which consists of a matte, black, opaque material, such as plastic or cardboard.

The masking layer 5 has recesses 9 on, so that in the places of the recesses 9 the reflection layer 12 , consisting of infrared filter foil 4 and retroreflective sheeting 3 , is visible.

Through the masking layer 5 thus arises via the corresponding recesses 9 the code pattern C of the optical marker 1 , The code pattern C may be, for example, the masking layer 5 be cut out or punched out.

The masking layer 5 does not extend to the edge 6 of the optical marker 1 , so in the edge area 6 of the optical marker 1 again the reflection layer 12 visible and thus part of the code pattern C is.

The 3 shows an object detection device with an infrared camera 7 on a tripod 11 is arranged. With the camera 7 coupled is an infrared emitter 8th essentially in the direction of the viewing direction of the image capture device 7 shine. The infrared camera 7 takes an object to be detected 10 on which an optical marker 1 of the type already described is arranged.

In the visible range, the optical marker works 1 Consistently black or gray, so that he, for example, to a black surface of the object 10 without affecting the visual impression of the object 10 integrate. In the infrared range, however, the code pattern C is visible, so that the object 10 can be recorded and tracked.

About the marker 1 For example, the type of object 10 be determined. Furthermore, the position, orientation and movement of the object 10 relative to the camera 7 be recorded.

The optical marker can thus be used in augmented reality systems, in which a virtual reality and the reality are combined and partially overlaid. One way of merging real and virtual image data, for example, in the US 6,166,744 described. A tracking method is further in the DE 10 2007 060 263 A1 described.

To the image capture device 7 is a calculator for capturing the marker and generating augmented reality 13 connected to a monitor 14 connected to display the augmented reality.

LIST OF REFERENCE NUMBERS

1

optical marker

2

backing

3

retroreflective layer

4

Infrared filter

5

masking layer

6

Edge of the marker

7

Infrared camera

8th

Infrared heaters

9

recess

10

object

11

tripod

12

reflective layer

13

computer

14

monitor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004046144 A1 [0007]
• DE 69628766 T2 [0013]
• US 6166744 [0040]
• DE 102007060263 A1 [0040]

Claims (13)

Optical marker with a code pattern (C) of different reflecting surfaces characterized by a reflection layer ( 12 ) over which a masking layer ( 5 ), the recesses ( 9 ) for generating the code pattern (C). Marker according to claim 1, characterized in that the reflection layer ( 12 ) a retroreflective layer ( 3 ). Marker according to claim 1 or 2, characterized in that the reflection layer ( 12 ) an IR filter ( 4 ). Marker according to claim 3, characterized in that the IR filter ( 4 ) is film-shaped, in particular shiny, designed. Marker according to one of the preceding claims, characterized in that the masking layer ( 5 ) reflects less light in the visible range than the reflection layer ( 12 ). Marker according to one of the preceding claims, characterized in that the masking layer ( 5 ) has a matte surface. Marker according to one of the preceding claims, characterized in that the reflection layer ( 12 ) has the same color as the masking layer ( 5 ). Marker according to claim 7, characterized in that the masking layer ( 5 ) and the reflection layer ( 12 ) are gray and / or black. Marker according to one of the preceding claims, characterized in that the reflection layer ( 12 ) of a carrier layer ( 2 ) will be carried. Object detection device with an image capture device ( 7 ) and an optical marker ( 1 ) according to one of the preceding claims for arrangement on an object to be detected ( 10 ). Object detection device according to claim 10, characterized in that the image capture device is an IR camera ( 7 ). Object detection device according to claim 10 or 11, characterized by an IR radiator ( 8th ). Object detection device according to claim 12, characterized in that the IR radiator ( 8th ) substantially in the direction of the viewing direction of the image capture device ( 7 ) shine.

Images