DE102018125422B4 - Method for testing or calibrating a stereo imaging device - Google Patents

Abstract

A method for testing or calibrating a stereo image capture device (10), comprising the following steps: arranging (103) the stereo image capture device (10) to be tested or calibrated in a predetermined position and in a predetermined orientation relative to a line (51) or Edge (52), wherein in the predetermined position and orientation the line (51) or edge (52) does not lie in a plane orthogonal to the main viewing direction (18) of the stereo image capturing device (10); capturing (104) a stereo image that an image intended for perception with the left eye and an image intended for perception with the right eye comprises, by means of the stereo image acquisition device (10); superimposing (105) the image intended for perception with the left eye and the image for Perception with the right eye of a certain image on a common image display surface in order to determine a position of an intersection of the representation (91) of the Line (51) or edge (52) in the image intended for perception with the left eye and the representation (92) of the line (51) or edge (52) in the image intended for perception with the right eye.

Description

The present invention is related to a method of testing or calibrating a stereo image capture device.

A stereo endoscope, a stereo exoscope, a stereo microscope or some other stereo image acquisition device generates two (or, for alternative orientations of the base, more) images of the viewed object from two somewhat different viewing directions. One of these images is intended for perception by the left or right eye of a human observer. For this purpose, the stereo image acquisition device comprises a corresponding number of parallel or mutually inclined beam paths, which, however, can at least partially lie in the same objective or in the same imaging device.

The images generated by the stereo image acquisition device can be viewed directly through eyepieces or converted by image sensors into image signals that represent the images. These image sensors can be components of the stereo image acquisition device or of cameras coupled to the stereo image acquisition device. The image signals generated by image sensors can be stored and / or processed and / or a screen or a projector or a visual output device worn on the head (often also referred to as video glasses, in English as a head mounted device) or another image display device so that they control reproduces the images.

A screen or a projector reproduces the image intended for perception with the left eye and the image intended for perception with the right eye, for example alternately or with different polarization. A viewer wears special glasses through which each of his eyes can only see the image intended for this eye.

When viewing the screen or the projected image without the special glasses, a viewer perceives the image intended for perception with the left eye and the image intended for perception with the right eye simultaneously and superimposed. The spatial distance between the reproduction of an object in the image intended for perception with the left eye and the reproduction of the same object in the image intended for perception with the right eye is referred to as disparity. The - usually at least approximately flat - surface in which objects lie that are reproduced with the disparity zero is referred to here as the zero plane. When viewed with the aforementioned special glasses, these objects appear to be in the image display area, i.e. in the surface of the screen or in the plane onto which the images are projected.

After a stereo endoscope, stereo exoscope, stereo microscope, or other stereo imaging device has been manufactured, its optical properties must be calibrated. Among other things, the distance between the zero plane and the stereo image capture device must be verified or calibrated.

The optical properties of a stereo image acquisition device, for example the position of the zero plane, can change due to aging or improper handling. This has an influence on the perception of a stereo image captured by means of the stereo image capturing device. A changed position of the zero plane can be perceived by a user as irritating or tiring or can lead to a more rapid fatigue of the user. It is therefore desirable to test or calibrate a stereo imaging device prior to use.

In WO 2016/070318 A1 describes a method and a system for calibrating multiple cameras, in particular for assigning image coordinates and global coordinates, by means of a calibration target (paragraphs [0003], [0004]). The calibration target can be three-dimensional and comprise several lines or other reference markings (paragraph [0075]).

The US2010 / 0245541A1 discloses a device in the form of a so-called slanted edge target for determining the modulation transfer function (MTF) of an imaging system. The target has a straight dark line on a light background.

It is an object of the present invention to provide an improved method for testing or calibrating a stereo image capture device.

This problem is solved by the subject matter of the independent claim.

Embodiments of the present invention are based on the idea of using a calibration target when testing or calibrating a stereo image capturing device that has a line or edge running at an angle such that different points or sections of the line are at different distances from the stereo to be tested or calibrated Have the line or edge but not in a plane with the image capture device Base of the stereo image capture device lies. In the case of a superimposed representation of the image intended for perception with the left eye and the image intended for perception with the right eye, the reproduction of the line or edge in the image intended for perception with the left eye then crosses or intersects the reproduction of the line or edge in the image intended for perception with the right eye. The position of the intersection shows the position of the zero plane.

A test device for testing or calibration of a stereo image capture device comprises a line or edge, which is at least either continuous or interrupted or stepped, and a positioning device for positioning the stereo image capture device to be tested or calibrated at a predetermined position and in a predetermined orientation relative to the line or edge, wherein in the predetermined position and orientation of the stereo image capturing device to be tested or calibrated, the line or edge does not lie in a plane orthogonal to the main viewing direction of the stereo image capturing device.

The stereo image capturing device is intended in particular for medical applications and comprises in particular a stereo exoscope, a stereo endoscope or a stereo microscope. The stereo image capturing device comprises, in particular, two or more cameras or two or more image sensors that capture images of a viewed object from somewhat different viewing directions, similar to the way the two eyes of a healthy human observer do.

The direction of view of a camera is that half-line on which all objects lie that are imaged in the center of the image sensor of the camera. In the case of two cameras or two image sensors of a stereo image capturing device, the viewing directions of the two cameras can intersect, depending on the configuration. The point of intersection - and thus the zero plane of the stereo image capturing device - ideally has a predetermined distance from a light entry surface or another reference point of the stereo image capturing device. The bisector of both viewing directions, i.e. the straight line that lies in a single plane with the viewing directions of both cameras or image sensors and encloses the same angles smaller or significantly smaller than 45 degrees with both viewing directions, is referred to as the main viewing direction of the stereo image capturing device.

If, for example, due to a slight imperfection or a misalignment, the viewing directions of both cameras or image sensors are skewed, i.e. do not have an exact intersection, or if the stereo image capture device is designed so that the two viewing directions are aligned in parallel, the main viewing direction is the stereo Image capturing device is that straight line for which it applies that for each plane orthogonal to the straight line the point of intersection of the plane with the straight line lies exactly in the middle between the points of intersection of the plane with the viewing directions of the cameras or image sensors.

The distance between the centers of two image sensors of a stereo image acquisition device is referred to as the base or stereo base.

In many cases, a stereo image capturing device has two identical cameras or two identical lenses or other imaging devices and two identical image sensors, what is referred to as being identical which has identical properties within the scope of the manufacturing tolerances. At least in this case, the base is parallel to the straight line through the centers of both lenses and orthogonal to the main viewing direction of the stereo image capturing device, and the main viewing direction lies in the plane of symmetry of the base.

The line or edge can be continuous or interrupted, for example similar to a dashed line. The line or edge can be straight or curved, smooth (i.e. a continuously differentiable curve in the sense of mathematics) or not continuously differentiable at a finite number of points. An example of a non-smooth line or edge is a stepped or stepped line or edge. The line or edge can be stepped and broken at the same time.

The line can be applied to a correspondingly shaped surface, for example on a target surface that is tilted with respect to the main viewing direction, or can be introduced into it. For example, the line can be printed, punched, etched, or milled. The edge can be formed by the edge of a correspondingly shaped target surface or by the edge of a correspondingly shaped partial area of a target surface.

In particular, a test device in the form of a target with a flat target surface tilted with respect to the main viewing direction, on which a straight line or edge is arranged, can be manufactured easily and inexpensively and nevertheless enable a precise determination of the position of the zero plane.

In the case of a test device as described here, the positioning device comprises in particular at least either one gauge for defining the predetermined position in a form-fitting manner and the predetermined orientation of the stereo image capturing device to be tested or calibrated relative to the line or edge or a holding arm for holding the stereo image capturing device to be tested or calibrated at the predetermined position and in the predetermined orientation relative to the line or edge.

The teaching includes, in particular, a receptacle or an adapter for the stereo image acquisition device to be tested or its distal end or end facing the object to be viewed. This receptacle or this adapter has a shape corresponding to the shape of a part of the outer surface of the stereo image capturing device or its distal end, which provides a low-play or backlash-free and thus precisely form-fitting connection of the stereo image capturing device to the gauge in a predetermined relative position and Orientation made possible. The receptacle or this adapter is in particular rigidly connected to a calibration target to which the line or edge is attached, for example by a connecting rail or a connecting support. The receptacle or the adapter and thus the teaching defines the position and orientation of the stereo image capturing device relative to the line or edge in particular completely unambiguously or unambiguously except for a possible rotation around the main viewing direction of the stereo image capturing device.

In the case of a stereo endoscope, the receptacle or adapter is, for example, tubular and encloses a cavity, the cross section of which corresponds to the cross section of the distal end of the stereo endoscope to be tested or calibrated except for an unavoidable clearance. At one end facing the line or edge, the receptacle or the adapter can have a radially inwardly protruding collar or one or more radially inwardly protruding lugs which positively define a distance between the distal end of the stereo endoscope and the line or edge.

In the case of a stereo endoscope with the main line of sight parallel to the longitudinal axis of its distal end, the receptacle or the adapter can enable rotation of the stereo endoscope around the longitudinal axis of its distal end and thus around its main line of sight. A suitable angular position of the line or edge relative to the base of the stereo endoscope (namely not parallel, but as orthogonal as possible to the base) is set in this case, in particular under visual control.

If the positioning device comprises a holding arm, this holding arm can in particular be moved by a motor and has one or more translational and / or rotational degrees of freedom in which it can be changed by a motor. In this case, the holding arm has, in particular, position sensors for detecting positions of its degrees of freedom or, for example, has stepping motors in order to move to defined positions.

A test device, as described here, furthermore comprises, in particular, a scale near the line or edge which, at the predetermined position and orientation, contains information about distances of several locations on the line or edge from the stereo image acquisition device to be tested or calibrated.

A test device for testing or calibration of a stereo image capture device comprises a line or edge which is at least either continuous or interrupted or stepped, and which is not in a plane at a predetermined position and orientation relative to the stereo image capture device to be tested or to be calibrated is orthogonal to the main viewing direction of the stereo image capturing device, and a scale near the line or edge, which at the predetermined position and orientation relative to the stereo image capturing device to be checked or calibrated information about distances of several locations on the line or edge from the to includes stereo imaging device to be tested or calibrated.

An angle between the line or edge on the one hand and the main viewing direction of the stereo image capturing device arranged in the intended position and orientation on the other hand is in particular at most 80 degrees or at most 70 degrees or at most 60 degrees or at most 50 degrees or at most 40 degrees.

The scale includes, for example, several lines of the same or different lengths and / or widths and / or colors at several positions. Furthermore, a label can be provided which indicates the limits of the permissible area and / or distances from the light entry surface or another reference location on a stereo image display device which is arranged in the predetermined position and orientation relative to the line or edge.

In further features, properties, functions and applications, the test device can correspond to the other test devices described here.

In a test device as described here, a scale division is in particular stretched by a factor which corresponds to the inverse of the cosine of an angle between the scale and the viewing direction of the stereo image acquisition device to be tested or calibrated.

For example, in the case of a line or edge that forms an angle of 45 degrees with the main viewing direction of the stereo image capturing device to be tested or calibrated, the scale division is stretched by a factor that corresponds to the square root of two (approx. 1.41). In this case, for example, the distance between two lines or other signs on the scale that identify two locations whose distances from the light entry surface of the stereo image acquisition device to be checked or calibrated differ by 10 mm is approximately 14.1 mm.

With the predetermined position and orientation of the stereo image capturing device to be checked or calibrated, this stretching of the scale division can enable the distance of the zero plane from the stereo image capturing device to be read directly.

In the case of a test device as described here, the line or edge is in particular straight, at least in sections.

In the case of a test device as described here, the line or edge in particular at least partially encloses an angle with the main viewing direction of the stereo image capturing device in its predetermined position and orientation which is not less than 20 degrees and not greater than 70 degrees.

With the predetermined position and orientation of the stereo image capturing device to be tested or calibrated relative to the line or edge, the entire line or edge or at least a portion of the line or edge with the main direction of view of the stereo image capturing device in particular forms an angle that is not smaller than 10 degrees or not smaller than 20 degrees or not smaller than 30 degrees or not smaller than 40 degrees, and at the same time not larger than 80 degrees or not larger than 70 degrees or not larger than 60 degrees or not larger than 50 degrees.

In a test device as described here, the line or edge lies in particular sections or completely in a plane which is orthogonal to a base of the stereo image acquisition device to be tested or calibrated in its predetermined position and orientation, or closes with this plane make an angle no greater than 40 degrees.

The line or edge lies in particular in sections or completely in the plane of symmetry of the base of the stereo image capturing device to be checked or calibrated in its predetermined position and orientation. Alternatively, a portion of the line or edge or the entire line or edge can enclose an angle that is no greater than 50 degrees, or no greater than 40 degrees, or no greater than 30 degrees, or no greater than 20 degrees, or no greater than 10 degrees. This means that the angle between a section of the line or edge or the entire line or edge on the one hand and the base on the other hand includes an angle which is not less than 40 degrees or not less than 50 degrees or not less than 60 degrees or not less than 70 degrees or not less than 80 degrees.

In a test device as described here, the line or edge is in particular orthogonal to a base of the stereo image capturing device to be tested or calibrated in its predetermined position and orientation, or the angle between the line or edge and the base is not smaller than 50 degrees.

The angle between the line or edge on the one hand and the base on the other hand is in particular not less than 40 degrees or not less than 50 degrees or not less than 60 degrees or not less than 70 degrees or not less than 80 degrees.

The larger the angle between the line or edge on the one hand and the base of the stereo image capturing device on the other hand, the more accurate and reliable the position of the intersection of the reproduction of the line or edge in the image intended for perception with the left eye and the reproduction of the Line or edge in the image intended for perception with the right eye.

A test device, as it is described here, in particular further comprises a target surface which, in the predetermined position and orientation of the stereo image acquisition device, faces relative to the line or edge of the stereo image acquisition device, the line or edge being arranged on the target surface.

In the case of a test device as described here, the target surface is in particular at least in sections not orthogonal to the main viewing direction of the stereo image acquisition device in its predetermined position and orientation.

In the case of a test device as described here, the target surface is in particular flat and forms an angle with the main viewing direction of the stereo image recording device in its predetermined position and orientation which is not less than 20 degrees and not greater than 70 degrees.

The angle between the target surface and the main line of sight of the stereo image capture device in its predetermined position and Orientation and the target surface is particularly not less than 10 degrees, or not less than 20 degrees, or not less than 30 degrees, or not less than 40 degrees. The angle between the target surface and the main viewing direction of the stereo image capture device in its predetermined position and orientation and the target surface is in particular not greater than 80 degrees or not greater than 70 degrees or not greater than 60 degrees or not greater than 50 degrees.

A method for testing or calibrating a stereo image capturing device comprises a step of arranging the stereo image capturing device to be tested or to be calibrated in a predetermined position and in a predetermined orientation relative to a line or edge, wherein the predetermined position and orientation the line or Edge does not lie in a plane orthogonal to the main viewing direction of the stereo image capturing device; a step of capturing a stereo image including an image intended for perception with the left eye and an image intended for perception with the right eye by means of the stereo image acquisition device; a step of superimposing the image intended for perception with the left eye and the image intended for perception with the right eye on a common image display surface in order to determine a position of an intersection of the representation of the line or edge in the for perception with the specific image and the representation of the line or edge in the image intended for perception with the right eye.

The method can in particular be applied to stereo image acquisition devices or can be carried out with stereo image acquisition devices for which a test device as described here is provided and designed. The method can be carried out in particular with a test device as described here.

A method as described here further comprises, in particular, a step of determining a position of an intersection point of the representation of the line or edge in the image intended for perception with the left eye and the representation of the line or edge in the image with the right eye.

The step of determining the position of the intersection point is carried out in particular after the step of overlaying. The step of determining the position of the intersection point can be carried out by a computer program product or, with the aid of such, by a human being.

A method as described here also includes, in particular, a step of projecting a scale or an identification of a permissible area or an identification of an inadmissible area or a marking of a boundary between an admissible area and an inadmissible area onto the calibration target or onto a target surface or a step of fading in a scale at least either in the image intended for perception with the left eye or in the image intended for perception with the right eye or in a superimposition of the image intended for perception with the left eye and that for the Perception of a certain image with the right eye, the scale being designed to enable the position of the intersection of the representations of the line or edge to be determined quantitatively.

The scale can be displayed in an analog manner or digitally, in particular by modifying image signals for an image display device.

In a method as described here, arranging the stereo image capturing device to be tested or calibrated comprises, in particular, arranging the stereo image capturing device to be tested or calibrated in a predetermined position and in a predetermined orientation relative to a test device like them is described here.

The present invention can be implemented as a computer program with program code for performing or controlling a method as described here.

Figure list

• 1 eine schematische Darstellung eines Stereo-Exoskops und einer Prüfvorrichtung;
• 2 eine weitere schematische Darstellung des Stereo-Exoskops und der Prüfvorrichtung aus 1;
• 3 eine schematische Darstellung einer Targetfläche an der Prüfvorrichtung aus den 1 und 2;
• 4 eine schematische Darstellung einer überlagerten Wiedergabe zweier für die Wahrnehmung mit jeweils einem Auge vorgesehenen Bilder der Targetfläche aus 3;
• 5 eine schematische Darstellung eines Stereo-Exoskops und einer weiteren Prüfvorrichtung;
• 6 eine schematische Darstellung eines Stereo-Exoskops und einer weiteren Prüfvorrichtung;
• 7 eine schematische Darstellung eines Stereo-Endoskops und einer weiteren Prüfvorrichtung;
• 8 ein schematisches Flussdiagramm.

In the following, embodiments are explained in more detail with reference to the accompanying figures. Show it:

• 1 a schematic representation of a stereo exoscope and a test device;
• 2 a further schematic representation of the stereo exoscope and the test device 1 ;
• 3 a schematic representation of a target surface on the test device from FIG 1 and 2 ;
• 4th a schematic representation of a superimposed reproduction of two images of the target area provided for perception with one eye each 3 ;
• 5 a schematic representation of a stereo exoscope and a further test device;
• 6th a schematic representation of a stereo exoscope and a further test device;
• 7th a schematic representation of a stereo endoscope and a further test device;
• 8th a schematic flow diagram.

Description of the embodiments

1 shows a schematic representation of a stereo image capturing device 10 , which is designed as a stereo exoscope in this example, and a test device 40 . Features of the stereo exoscope 10 themselves are particularly relevant insofar as the test device 40 of the properties of the stereo exoscope 10 is adapted. Therefore, there are only contours of the housing of the stereo exoscope 10 and internal components necessary for the functioning of the test device 40 are relevant. The testing device 40 is shown in a section along a plane, with cut surfaces of the test device 40 are shown hatched.

The stereo exoscope 10 a first includes cameras 20th for capturing an image intended for perception with the left eye. The first camera includes an image sensor 21st and a lens 23 . The representation of the lens shows the contours of a section along its optical axis for intuitive recognition. In the example shown, the light-sensitive surface is the image sensor 21st and the main planes of the lens 23 each orthogonal to the cutting plane of the 1 .

The stereo exoscope 10 furthermore comprises a second camera for capturing an image intended for perception with the right eye. This second camera is in front of the cutting plane 1 and is therefore in 1 not visible. The base of the stereo exoscope 10 , ie the straight line between the center 22nd of the image sensor 21st of the first camera and the center of the image sensor of the second camera is orthogonal to the plane of the drawing 1 .

As the direction of view of the first camera 20th or that of the second camera is the half-line on which all objects lie in the center 22nd of the image sensor 21st the respective camera 20th be mapped. The direction of the first camera 20th and the direction of view of the second camera lie in one plane and in the present exemplary embodiment intersect at an angle in the zero plane. As the main line of sight 18th of the stereo exoscope 10 is called the bisector of this angle. With both directions of view, it forms an angle that is significantly smaller than 45 degrees. The main line of sight 18th of the stereo exoscope 10 lies in the cutting plane of the 1 .

The stereo exoscope 10 also has a window component 15th with a light entry surface 16 on. The window component 15th made of glass, sapphire or another optically transparent material closes an opening in the housing of the stereo exoscope 10 fluid-tight. Through the window component 15th can light emanating from an observed object to the first camera 20th and get to the second camera.

One proximal end 17th of the stereo exoscope 10 is mostly arranged to the right outside the area shown. At the proximal end 17th are for example a user interface and / or one or more connectors that are included in 1 are not visible, arranged. The stereo exoscope 10 Receive control signals and / or electrical and / or optical power and an image signal from the stereo exoscope 10 represents captured stereo image.

The testing device 40 includes a calibration target 50 . In the example shown, the calibration target has the shape of a prism, that is to say a cylinder with a polygonal, namely essentially triangular, cross section. The edge of the in 1 The cross section shown lies in the lateral surface of the prism. The generatrices or generatrices of the prism are orthogonal to the cutting plane of the 1 , All areas of the outer surface of the prism are orthogonal to the cutting plane of the 1 .

A flat area of the outer surface of the prism (namely the area of which the in 1 edge of the cross-section shown below) is orthogonal to the main viewing direction 18th of the stereo exoscope 10 . Another flat area of the outer surface of the prism (namely the area of which the in 1 The edge of the cross-section shown on the right is parallel to the main viewing direction 18th of the stereo exoscope 10 . Another flat area of the outer surface of the prism forms a target surface 53 . The main line of sight 18th of the stereo exoscope 10 closes with the target surface 53 an angle α that is significantly greater than 0 degrees and significantly smaller than 90 degrees. The angle α is in particular in the range from 20 degrees to 80 degrees or in the range from 30 degrees to 60 degrees or in the range from 40 degrees to 50 degrees. In the example shown, the angle α is approximately 45 degrees.

The testing device 40 also includes a teaching 60 for the positive definition of a predetermined position and orientation of the stereo exoscope 10 relative to the calibration target 50 . The teaching 60 includes a recording 61 for the stereo Exoscope 10 . In the example shown, the recording is for the in 1 Distal end of the stereo exoscope shown on the left 10 is provided and has essentially the shape of a cup with an opening in the bottom. The shape of the shot 10 thus corresponds exactly to the shape of a part of the outer surface of the stereo exoscope 10 that the stereo exoscope 10 relative to the recording 61 occupies a predetermined position and orientation.

The teaching 60 the testing device 40 further comprises a rigid link arm 65 taking the shot 61 on the one hand and the calibration target 50 on the other hand, mechanically rigidly connects. This takes the stereo exoscope 10 due to the geometry of the recording 61 and the link arm 65 predetermined position and orientation relative to the calibration target 50 one as soon as the stereo exoscope 10 flat on the receptacle in the intended manner 61 is applied.

2 shows another schematic representation of the stereo exoscope 10 and the testing device 40 out 1 . The drawing plane of the 2 is orthogonal to the plane of the drawing 1 and contains the main line of sight 18th of the stereo exoscope 10 . Otherwise, the type of display corresponds to the stereo exoscope 10 and the recording 61 in 2 the way they are represented in 1 . The recording 61 the teaching 60 is in 2 as in 1 shown in section. The connecting arm 65 the teaching 60 is behind the cutting plane of the 2 , accordingly only its contours are shown. The calibration target 50 is in 2 not shown in section, but in plan view, around its entire target area 53 to be able to represent.

In 2 is next to the first camera 20th for the acquisition of an image intended for perception with the left eye, the one already mentioned, but in the illustration in 1 invisible second camera 30th visible. The second camera 30th is intended and designed for the acquisition of an image intended for perception with the right eye. The second camera 30th includes like the first camera 20th an image sensor 31 and a lens 33 . The first camera 20th and the second camera 30th are in particular the same, that is, they have identical properties.

The base 12th , the straight line connecting the middle 22nd of the image sensor 21st the first camera 20th and the middle 32 of the image sensor 31 the second camera 30th , is in 2 something from the image sensors 21st , 31 staggered away to make them stand out from the crowd. The base 12th lies in the cutting plane of the 2 and is orthogonal to the main line of sight 18th of the stereo exoscope 10 . The plane of symmetry 14th the base 12th is orthogonal to the cutting plane of the 2 and corresponds to the cutting plane of 1 . The main line of sight 18th of the stereo exoscope 10 lies in the plane of symmetry 14th the base 12th .

In 2 are the direction of view 28 the first camera 20th and the direction of view 38 the second camera 30th visible. The directions of view 28 , 38 both cameras 20th , 30th and the main line of sight 18th of the stereo exoscope 10 lie in the cutting plane of the 2 and intersect at one point. The level 19th orthogonal to the main line of sight 18th which is the intersection of the lines of sight 28 , 38 is called the zero level.

In 2 is also the target area 53 of the calibration target 50 visible, which is not shown in section, but in plan view. The target area 53 is not parallel to the plane of the drawing 2 , but closes with it the angle α (cf. 1 ) a.

At the target surface 50 is a line 51 provided which is orthogonal to the base 12th of the stereo exoscope 10 is. In the example shown, the line lies 51 in the plane of symmetry 14th the base 12th of the stereo exoscope 10 . That is why the line appears 51 in the projection of the 2 as an extension of the main line of sight 18th of the stereo exoscope 10 .

At the target surface 53 is also a scale 71 with a scale division 72 and a label 73 intended. The scale division 72 consists of lines orthogonal to the line 51 and orthogonal to the main line of sight 18th of the stereo exoscope 10 . The lines of the scale division 72 have different distances from the light entry surface 16 of the stereo exoscope 10 in his in 2 shown predetermined position and orientation relative to the calibration target 50 on. For example, two adjacent lines are at a distance from the light entry surface 16 of the stereo exoscope 10 that differ by 1 mm. In the example shown, some lines show the scale division 72 a greater length. Two adjacent longer lines of the scale division 72 have, for example, distances from the light entry surface 16 of the stereo exoscope 10 that differ by 5 mm.

In the example shown, the label includes 73 a common abbreviation for a lower limit, namely the letter sequence "min", and a common abbreviation for an upper limit, namely the letter sequence "max". Alternatively or additionally, the label 73 Numerical values comprise the distances between assigned lines of the scale division 72 from the light entry surface 16 of the stereo exoscope 10 specify.

At the target surface 53 is also a marking 75 within a permissible range. The marking 75 has the shape of two mirror-symmetrically arranged triangles with facing and slightly overlapping corners (referred to in seafaring as an hourglass). A waist of identification 75 lies at the desired or optimal spacing of the zero plane 19th from the light entry surface 16 of the stereo exoscope 10 .

Inside the marking 75 In the example shown, many identical and regularly arranged small circles, hexagons or other structures are arranged which enable a visual determination of the focal plane, that is to say that plane that is optimally captured by the stereo exoscope.

At the target surface 53 are also two labels 77 areas not permitted. The markings 77 of the non-permissible areas are adjacent to the marking on sides facing away from one another 75 of the allowable range. In the example shown, each label includes 77 the string "not ok", as an abbreviation for "not ok".

The line 51 who have favourited the scale 71 , the caption 73 , the markings 75 , 77 can each on the target surface 53 forming surface area of the calibration target 50 printed or produced by etching, milling or in any other way.

3 shows a schematic representation of the target area 53 on the calibration target 50 based on the 1 and 2 test device shown 40 . In contrast to 2 is the drawing plane of the 3 parallel to the target surface 53 .

In 3 is clearer than in 2 recognizable that the line 51 in the example shown only within the area indicated by the label 73 and by marking 75 marked permissible range. Alternatively, the line 51 also extend beyond the limits of the permissible range.

The entire target area 53 with all of the visible structures provided is stretched by a factor of 1 / cos (α). In the example shown with α = 45 degrees, the entire target area is 53 stretched by a factor of 1.41 (square root of 2).

4th shows a schematic representation of a superimposed reproduction of an image intended for perception with the left eye and an image of the target surface intended for perception with the right eye 53 out 3 .

Due to the inclination of the target surface 53 opposite the main line of sight 18th (see. 1 ) is the target area 53 distorted in both images, but in different ways. In particular, the playback 91 the line 51 in the image intended for perception with the left eye, inclined slightly to the right and the reproduction 92 the line 51 inclined slightly to the left in the image intended for perception with the right eye. The playback 91 the line 51 in the image intended for perception with the left eye and the reproduction 92 the line 51 in the image intended for perception with the right eye intersect at an intersection 93 .

The location of this intersection 93 gives the position of the zero plane 19th (see. 2 ) of the stereo exoscope 10 at. Therefore, in the in 4th The superimposed rendering of the two images shows the position of the zero plane 19th can be read. In the example shown here, the intersection is located 93 and thus the zero level 19th of the stereo exoscope 10 within the allowable range, but not exactly in the middle.

5 shows a schematic representation of the based on 1 and 2 shown or a similar stereo exoscope 10 as well as a test device 40 that are based on some features, properties and functions of the 1 to 4th test device shown is the same or similar. The type of representation in 5 corresponds to that of 2 . Features, properties and functions of the in 5 test device shown 40 in which these differ from the 1 to 4th test device shown differs.

In the 5 Test device shown 40 differs from the one based on the 1 to 4th test device shown in particular in the form of the calibration target 50 . The direction parallel to the base 12th of the stereo exoscope to be tested or calibrated 10 (i.e. in 5 horizontally measured) width of the target area 53 of the calibration target 50 is smaller than the one based on the 1 to 4th test device shown.

The target area 53 extends only on one side (in 5 : the right side) of the plane of symmetry 14th the base 12th of the stereo exoscope 10 in its predetermined position and orientation. In the plane of symmetry 14th shows the target area 53 an edge 52 on. On the other hand (in 5 : the left side) of the plane of symmetry shows the calibration target 50 a contrasting surface 54 which is orthogonal to the plane of the drawing 5 and orthogonal to the main line of sight 18th extends. The contrast surface 54 in particular has a contrasting color to the target surface 53 on.

Instead of the line 51 (see. 2 to 4th ) becomes the edge 52 at the target surface 53 from the stereo exoscope 10 detected. One advantage is that no line has to be generated, but only one, for example, on each flat target surface 53 The edge present as the edge must be placed differently, namely near the main viewing direction. A light-dark contrast or a colored contrast between the target surface 53 and the contrast area 54 can detect the edge 52 and an accurate determination of the position of the intersection of both representations of the edge 52 simplify.

6th shows a schematic representation of the based on 1 , 2 and 5 shown or a similar stereo exoscope 10 as well as a test device 40 which in some features, properties and functions are based on the 1 to 5 test devices shown is the same or similar. The type of representation in 6th corresponds to that of 1 . Features, properties and functions of the in 6th test device shown 40 in which these differ from the 1 to 5 different test devices shown.

In the 6th Test device shown 40 differs from the 1 to 5 Test devices shown in particular in that they do not have any teaching for the form-fitting definition of the predetermined position and orientation of the stereo exoscope to be tested or to be calibrated 10 relative to the calibration target 50 and thus relative to the line 51 (see. 2 to 4th ) or edge 52 (see. 5 ) includes.

Instead, the stereo exoscope is used 10 from a holding arm 80 held. The holding arm 80 includes a foundation 81 , which rests, for example, on the same table top and / or is connected to it on which the calibration target is also located 50 rests. The holding arm also includes 80 multiple segments 83 with each other and with the foundation 81 each by a joint 84 are connected. A free end 88 of the holding arm 80 is - for example by a coupling, not shown - with a recording 61 for the stereo exoscope 10 mechanically connected. The recording 61 has for example features and properties of the recording based on the 1 and 2 illustrated teaching 60 on. Alternatively and different from the representation in 6th can the distal end 88 of the holding arm 80 by a gripper with the stereo exoscope 10 be releasably connected.

The holding arm has in 6th invisible drives and position sensors for all through the joints 84 defined degrees of freedom. The holding arm can therefore be the stereo exoscope within given limits 10 hold in any positions and orientations. For testing or calibration, the holding arm is controlled in such a way that the stereo exoscope 10 relative to the calibration target 50 the position and orientation relative to the calibration target predetermined for the test or calibration 50 (and especially to a line or edge on it).

That in the 1 to 6th shown stereo exoscope 10 is just one example of a stereo image capturing device that can be made using the FIG 1 to 6th shown, but adapted to the respective stereo image capture device testing devices 40 can be checked or calibrated.

7th shows a schematic representation of a distal end of a shaft of a stereo endoscope 10 and another test device 40 . The type of representation in 7th corresponds to that of 1 and 6th . In the 7th Test device shown 40 is similar or identical in some features, properties and functions to those based on the 1 to 6th test devices shown. Features, properties and functions of the in 7th test device shown 40 in which these differ from the 1 to 4th different test devices shown.

The stereo endoscope 10 has a long thin shaft with a circular or substantially circular cross-section, the distal end of which in 7th is shown. At the distal end of the shaft of the stereo endoscope 10 are next to each other a first camera 20th for capturing an image provided for perception with the left eye and a second camera for capturing an image provided for perception with the right eye. Similar to the representations in the 1 and 6th is the basis of the in 7th shown stereo endoscope 10 orthogonal to the plane of the drawing 7th . The second camera is therefore in front of the cutting plane 7th and is in 7th not visible.

In the example shown, the first include cameras 20th and the second camera of the stereo endoscope 10 one image sensor each 21st and a lens 23 , which is a real image of a viewed object on the image sensor 21st generated. A window component 15th with a light entry surface 16 closes an opening at the distal end of the endoscope 10 fluid-tight, but optically transparent, so that light from an observed object enters the cameras 20th can arrive.

In the 7th Test device shown 40 differs from the 1 to 6th test devices shown in particular by having the inclusion 61 the teaching 60 to the distal end of the stereo endoscope 10 is adapted. The recording 61 encloses the distal end of the stereo endoscope 10 with little play and thus defines a predetermined position and orientation of the stereo endoscope in a form-fitting manner 10 relative to the calibration target 50 .

However, this applies, for example, in the described case of a circular cross section of the distal end of the shaft 10 not for the angular position of the stereo endoscope with respect to the longitudinal axis of the distal end of its shaft. Rather, the distal end of the stereo endoscope can in this case 10 in the recording 61 be rotated about its longitudinal axis. In this case, a suitable angular position is set in particular under visual control. Alternatively, the teaching 60 different from the representation in 7th to a proximal and non-rotationally symmetrical end of the stereo endoscope 10 range and define a predetermined angular position there in a form-fitting manner.

8th FIG. 8 shows a schematic flow diagram of a method for testing a stereo image acquisition device, in particular a stereo endoscope, a stereo exoscope or a stereo microscope. The method can be used in particular on stereo image acquisition devices and can be carried out by means of a test device as described here. However, the method can also be applied to stereo image acquisition devices and can be carried out by means of test devices that have features, properties and functions that are derived from the representations based on 1 to 7th differ. Nevertheless, the following are examples of reference numerals from the 1 to 7th used to simplify understanding.

With a first step 101 becomes a calibration target 50 provided. The calibration target 50 in particular has features and properties as they are based on 1 to 7th are shown.

In an optional second step 102 become one or more lines 51 and / or a scale 71 and / or a label 75 a permissible range and / or a marking 77 an impermissible area and / or further markings on a target surface 53 projected. Alternatively or additionally there are one or more lines 51 and / or a scale 71 and / or a label 75 a permissible range and / or a marking 77 an impermissible area and / or further markings by printing, etching, milling or in some other way already on the target surface 53 the one at the first step 101 provided testing device 40 permanently applied. Alternatively or additionally, the calibration target 50 an edge 52 exhibit.

In a third step 103 becomes the stereo imaging device to be tested or calibrated 10 arranged in a predetermined position and orientation relative to the calibration target. This is done in particular by means of a teaching 60 with the calibration target 50 is rigidly connected and the predetermined position and orientation of the stereo image acquisition device to be tested or to be calibrated 10 Defined positively relative to the calibration target. Alternatively, the third step 103 for example by means of a motor-driven holding arm 80 are executed.

At the predetermined position and orientation of the stereo image capturing device to be tested or calibrated 10 is the one on the calibration target 50 present or on a target surface 53 line projected from the calibration target 51 or the one on the calibration target 50 present edge 52 not orthogonal to the main line of sight 18th the stereo image capture device 10 . An angle between the line 51 or edge 52 one hand and the main line of sight 18th on the other hand is in particular at least 10 degrees and at most 80 degrees or at least 20 degrees and at most 70 degrees or at least 30 degrees and at most 60 degrees. The line 51 or edge 52 lies in particular in a plane of symmetry 14th the base 12th the stereo imaging device to be tested or calibrated 10 in their predetermined position and orientation or parallel to this plane of symmetry 14th .

In a fourth step 104 is by means of the stereo image acquisition device to be tested or calibrated 10 a stereo image of the calibration target is captured. That from the stereo image capture device 10 The captured stereo image includes an image intended for perception with the left eye and an image intended for perception with the right eye.

On a fifth step 105 the image intended for perception with the left eye and the image intended for perception with the right eye are displayed superimposed. This is done, for example, by a screen or by means of a projector on a projection surface. Both images can be superimposed by image processing before they are displayed. Alternatively, the two images can be displayed in different polarization or alternately, for example, and then viewed without special glasses that only made one of the images visible to each eye.

The superimposed rendering of the images includes the rendering in particular 91 one line 51 or edge 52 at the target surface 53 in the image intended for perception by the left eye and reproduction 92 the same line 51 or edge 52 in the image intended for perception by the right eye. Because of the slope of the line 51 or edge 52 opposite the main line of sight 18th the stereo image capturing device and the slightly different viewing directions from which the image intended for perception by the left eye and the image intended for perception by the right eye were captured are the two reproductions 91 , 92 the line 51 or edge 52 not parallel in the two pictures.

At an optional sixth step 106 becomes the position of an intersection 93 playback 91 the line 51 or edge 52 in the image intended for perception with the left eye and the reproduction 92 the same line 51 or edge 52 determined in the image intended for perception with the right eye. This position corresponds to the position of the zero plane of the stereo image capturing device. Using a scale 71 or a label 75 an allowable range or a label 77 of a non-permissible range, it can be determined at which position the zero plane is located and / or whether the zero plane is located within a permissible range. The sixth step 106 can by a user of the stereo image capture device 10 are executed.

At an optional seventh step 107 becomes the position of a focal plane, i.e. the plane (or, more generally, surface) in which objects lie that are captured by the stereo image acquisition device 10 are mapped in an optimally sharp manner. At the same time, the limits of the depth of field of the stereo image capturing device 10 are detected, that is, the boundaries of the area within which objects lie, which are detected by the stereo image detection device 10 within the resolution of the image sensors 21st , 31 or are imaged in focus according to other criteria.

List of reference symbols

10

Stereo image acquisition device, in particular a stereo exoscope or stereo endoscope

12

Base of the stereo image capture device 10

14th

Plane of symmetry of the base 12th the stereo image capture device 10

15th

Window component of the stereo image capture device 10

16

Light entry surface on the window component 15th

17th

proximal end of the stereo imaging device 10

18th

Main line of sight of the stereo image capture device 10

19th

Zero level of the stereo image capture device 10

20th

first camera of the stereo image capture device 10 , for capturing an image intended for perception with the left eye

21st

First camera image sensor 20th

22nd

Center of the image sensor 21st the first camera 20th

23

Lens of the first camera 20th

28

Direction of view of the first camera 20th

30th

second camera of the stereo image capture device 20th , for capturing an image intended for perception with the right eye

31

Image sensor of the second camera 30th

32

Center of the image sensor 31 the second camera 30th

33

Second camera lens 30th

38

Direction of view of the second camera 30th

40

Testing device

50

Calibration target, in particular part of the test device 40

51

Line on the calibration target 50

52

Edge on the calibration target 50

53

Target area on the calibration target 50 on which the line 51 or the edge 52 is arranged, or the edge of which is the edge 52 forms

54

black background area on the calibration target 50

55

Section of the line 51 which is orthogonal to the main line of sight 18th the stereo image capture device 10 is

56

Light source of the calibration target 50

60

Teaching for the positive definition of a predetermined position and orientation of the stereo image acquisition device to be tested or to be calibrated 10

61

Recording for low-clearance recording of the stereo image capture device 10 in a predetermined position and orientation

65

rigid connecting arm for mechanically rigid connection of the mount 61 with the calibration target 50

71

Scale on the target surface 53

72

Graduation of the scale 71

73

Labeling on the scale 71

75

Identification of an allowable area

77

Identification of a prohibited area

80

Holding arm

81

Foundation of the holding arm 80

83

Segment of the holding arm 80

84

Joint between two segments of the holding arm 80

88

free end of the holding arm 80

91

Representation of the line 51 in the image intended for perception with the left eye

92

Representation of the line 51 in the image intended for perception with the right eye

93

Intersection of the two representations 91 , 92 the line 51

101

first step (provision of a calibration target)

102

second step (projecting a scale onto the calibration target)

103

third step (arranging a stereo image acquisition device in a predetermined position and orientation relative to the calibration target)

104

Fourth step (acquisition of a stereo image of the calibration target by means of the stereo image acquisition device)

105

fifth step (superimposed display of the stereo image)

106

sixth step (determining a position of an intersection)

107

seventh step (determining the position of a focal plane)

Claims (1)

A method for testing or calibrating a stereo image capture device (10), comprising the following steps: Arranging (103) the stereo image acquisition device (10) to be checked or calibrated in a predetermined position and in a predetermined orientation relative to a line (51) or edge (52), the line (51) in the predetermined position and orientation or edge (52) does not lie in a plane orthogonal to the main viewing direction (18) of the stereo image capturing device (10); Capturing (104) a stereo image comprising an image intended for perception with the left eye and an image intended for perception with the right eye by means of the stereo image acquisition device (10); Overlaying (105) the image intended for perception with the left eye and the image intended for perception with the right eye on a common image display surface in order to determine a position of an intersection of the representation (91) of the line (51) or edge ( 52) in the image intended for perception with the left eye and the representation (92) of the line (51) or edge (52) in the image intended for perception with the right eye.

Images