Camera adjustment

Cameras are adjusted by setting magnifications of two or more cameras to be substantially equal, focusing the two or more cameras, and setting the two or more cameras so that portions of an object captured thereby when displayed are aligned.

BACKGROUND

During videoconferencing, cameras are often used for transmitting images from one conference facility to one or more displays at one or more remote conference facilities. Large conference facilities with multiple participants may require multiple cameras and displays to capture all of the participants. When the images from these cameras are shown together, the separation between displays can create geometric distortions that might make the images distracting. Some conference facilities use multiple cameras, but do not have an accurate arrangement to correct for distortions. A single camera may be used for wide shots to prevent distortion, but this may result in unsatisfactory eye contact at sides the displays.

DETAILED DESCRIPTION

In the following detailed description of the present embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice disclosed subject matter, and it is to be understood that other embodiments may be utilized and that process, changes may be made without departing from the scope of the claimed subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the claimed subject matter is defined only by the appended claims and equivalents thereof.

FIG. 1is a plan view illustrating a camera and a display setup disposed in a room, such as a videoconferencing room, according to an embodiment.FIG. 2is a view taken along line2-2ofFIG. 1, according to another embodiment.FIG. 3is a view taken along line3-3ofFIG. 1, according to another embodiment. For one embodiment, a segmented display101, e.g., located on a wall of the room, includes display segments100. For another embodiment, cameras1021to1023are respectively positioned above display segments1001to1003, as shown inFIG. 2. For some embodiments, display segments100form angles to each other, as shown inFIG. 1. For other embodiments, display segments100are substantially coplanar or are coplanar.

Display segments1001,1002,1003respectively have display widths of dw,1, dw,2, and dw,3. A distance a1-2separates display1001from display1002, and a distance a2-3separates display1002from display1003. For one embodiment, the distances a include the bezels104of successively adjacent display segments100and a gap between these bezels, as shown inFIG. 2. For another embodiment, the gap may be eliminated; the bezels104may be eliminated; or both the gap and the bezels104may be eliminated. Each of display segments100may have the same height dhfor some embodiments, as shown inFIG. 2.

Cameras1021,1022, and1023respectively have optical axes1101,1102, and1103, as shown inFIG. 1. Optical axes1101,1102, and1103respectively bisect angles of view a1, a2, and a3respectively of cameras1021,1022, and1023, as shown inFIG. 1. Cameras1021,1022, and1023can be moved (or panned) so as to respectively sweep out pan angles φ1, φ2, and φ3in the plane ofFIG. 1, as shown inFIG. 1. Cameras102can be moved (or tilted) so as to respectively sweep out tilt angles θ in the plane ofFIG. 3, as shown inFIG. 3for a tilt angle θ2of camera1022, where a zero tilt angle occurs when the optical axes are horizontal. Cameras102can be moved (or rolled) about there respective optical axes110as indicated by arrow305inFIG. 3. For other embodiments, cameras102may be located below display segments100and may be directed along a horizontal line330(FIG. 3), in which case the tilt angle θ is zero.

Cameras1021,1022, and1023respectively have regions of useful image quality (or depths of field)3001,3002, and3003, as shown inFIG. 1. As shown for camera1022, inFIG. 3, the region of useful image quality3002lies within the angle of view between a near bounding plane3022and a far bounding plane3042that are perpendicular to optical axis1102, and are respectively at distances fnear,2and ffar,2from camera1022. Note that near bounding plane3022corresponds to the bottom of the image field of camera1022, and far bounding plane3042corresponds to the top of the image field of camera1022. Each camera102has a focal distance f, e.g., focal distance f2for camera1022(FIG. 3), between the distances fnearand ffar. A focal plane is located between the near and far planes that bound the region useful image quality at the focal distance f, e.g., as shown inFIG. 3for a focal plane1752located at focal distance f2from camera1022between near bounding plane3022and far bounding plane3042.

The room includes a table150, as shown inFIG. 1, that for one embodiment may include table segments,1521,1522, and1523respectively corresponding to cameras1021,1022, and1023. For another embodiment, each table segment152may be an individual table. For various embodiments, edges154at the back of the respective table segments152, facing the back of the room, might not lie in the same plane, but are at angles to each other, as shown inFIG. 1. For one embodiment, table150may have a curved edge. Alternatively, for some embodiments, e.g., involving a straight table, the edges154of the respective table segments152are substantially colinear. For one embodiment, a wall320, opposite display101, may be located within region of useful image quality300, as shown inFIG. 3.

Note that, a person sitting at the table behind the edge154is in the region of useful image quality300, as is a portion of the table in front of the edge154, as shown inFIG. 3. This enables objects placed on the table to be within the region of useful image quality300. For another embodiment, wall320may coincide with the far bounding plane3042of the region of useful image quality300. For some embodiments, e.g., embodiments involving a straight table edge at the back of the table, cameras102may have the same focal distance f. For other embodiments, the optical axes of cameras102may make the same tilt angle θ with the horizontal.

For one embodiment, the tilt angle θ may be selected so that the region of useful image quality300is positioned above the table, e.g., to prevent corners of the table and features of the table that are not parallel to a display, such as seams, inlay, grain or surface patterns, from being displayed. For embodiments where the tilt angle θ is zero, the vertical distance above the floor of the room at which the cameras are located is selected so that the region of useful image quality300is positioned above the table. Positioning the region of useful image quality above the table, acts to reduce errors in perspective that may occur when an observer's line of sight, that may be represented by the horizontal line330inFIG. 3, does not coincide with the optical axes of the cameras, as illustrated for the optical axis1102of camera1022inFIG. 3. For one embodiment, the region of useful image quality may be adjusted so that a displayed table image is limited to the bottom portion of the display and is about 15 percent of the height of the display.

For one embodiment, a chair, such as a chair340ofFIG. 3, may be located behind each of table segments1521,1522, and1523. For another embodiment, focal planes1751,1752, and1753(FIG. 1), respectively of cameras1021,1022, and1023, respectively intersect these chairs and thus persons seated in these chairs. Note that for one embodiment, each chair and a person sitting therein are located on an optical axis110. Focal planes1751,1752, and1753respectively have widths cw,1, cw,2, and cw,3respectively perpendicular to optical axes1101,1102, and1103. For another embodiment, the widths cw,1, cw,2, and cw,3may be substantially equal to each other. For one embodiment, focal planes175have a heights ch, such as ch,2, as shown inFIG. 3for focal plane1752.

For other embodiments, focal planes175are at angles to each other, as shown inFIG. 1. For some embodiments, planes175are coplaner, e.g., for embodiments where the table edge is straight. For one embodiment, a distance b1-2separates plane1751from plane1752, and a distance b2-3separates plane1752from plane1753. Note that adjusting the pan angles φ of cameras102and their rolls acts to adjust the separation distances b. For some embodiments, focal planes175may coincide with edges154of table segments152.

For various embodiments, rooms having the camera setups, the display setups, and the table and chair placements of the embodiments described above in conjunction withFIGS. 1-3are located at sites remote from each other. For example, for one embodiment, a room at a first site may include displays100, cameras102, and a table150, where people, such as participants in a videoconference, sitting at table150observe images received at displays100from a second site remote from the first site. The second site may include displays100, cameras102, and a table150, where people, such as participants in a videoconference, sitting at table150observe images received at displays100from the first site. For one embodiment, the displays100, e.g., displays1001,1002, and1003, of the first site respectively receive images from the cameras102, e.g., cameras1021,1022, and1023, at the second site and vice versa. For another embodiment, the cameras102at one site are adjusted so that an image displayed by the displays100at the other site appears as a single continuous image. That is, sizes and distances are preserved across the displays100.

For one embodiment, equating the magnifications of the respective cameras102preserves the image sizes. Magnification may be defined as the ratio of an object's size in the image field to the size (width or height) of that object in a display field (or the size of that object as displayed on a display segment100). For example, in terms ofFIG. 1, the magnifications of cameras102are
Mcamera=(c/d)1=(c/d)2=(c/d)3(1)
where Mcamerais the magnification, c is a horizontal or vertical distance in, or of, an image field (or an focal plane175), d is a horizontal or vertical distance in, or of, a display field (or a display segment100), and subscripts1,2,3respectively correspond the subscripts of cameras1021,1022, and1023ofFIG. 1.

For other embodiments, fromFIG. 1, a global or room magnification may be defined as the ratio of an overall length in an overall image field to an overall length in an overall display field:
Mglobal=(cw,1+b1-2+cw,2+b2-3+cw,3)/(dw,1+a1-2+dw,2+a2-3+dw,3)  (2)

For some embodiments, the separation distances a between successive display segments100in a display field at the first site may be different than the separation distances a between successive display segments100in a display field at the second site. This may require the separation distances b between successive focal planes175at the first site to be different than the separation distances b between successive focal planes175at the second site. For one embodiment, equating the magnifications at the first and second sites preserves the sizes and distances between the two sites. The magnification at the first and second sites may be defined as the ratio of lengths in image field to the lengths in the display field. Therefore,
Mfirst=(b/a)first=(c/d)first=Msecond=(b/a)second=(c/d)second(3)
where M is the magnification, a a separation distance between successive display segments, b a separation distance between successive focal planes, c a horizontal or vertical distance in the image field, d a horizontal or vertical distance in the display field, the subscript first refers to the first site, and the subscript second refers to the second site. Note that equation 3 enables the separation distances b at the first and second sites to be determined from known values of a, c, and d at the first and second sites.

FIG. 4illustrates a multipoint setup, according to another embodiment. Multipoint results from connecting more than two sites at one time. As shown inFIG. 4, a site W has a display401Whaving display segments400W,1,400W,2, and400W,3that respectively receive images from sites X, Y, and Z. Display segments400W,1,400W,2, and400W,3respectively have display (or display field) sizes D1, D2, and D3. For one embodiment, display segment400W,1may be separated from display segment400W,2by a distance A1-2, while display segment400W,2may be separated from display segment400W,3by a distance A2-3. Sites X, Y, and Z respectively have cameras402X,402Y, and402Z. Each of sites X, Y, and Z has a table450that may have a curved or straight edge454on a side opposite a camera402. Cameras402X,402Y, and402Zrespectively have image field sizes CX, CY, and CZ, e.g., at table edge454of their corresponding tables450, as shown inFIG. 4, or at one or more chairs (not shown inFIG. 4) located behind table edge454of their corresponding tables450. Cameras402X,402Y, and402Zrespectively acquire one or more images and respectively transmit the one or more images to display segments400W,1,400W,2, and400W,3at site W.

The size of the images from sites X, Y, and Z should be preserved (or appear substantially continuous) across display segments400W,1,400W,2, and400W,3at site W. Selecting the magnification of the images displayed at display segments400W,1,400W,2, and400W,3to be the same accomplishes this. The magnification of an image displayed on each display segment400may be defined as the ratio of the size of the image field corresponding to that display to the size of the display field of that display. Therefore, for one embodiment, size preservation across display segments400W,1,400W,2, and400W,3is accomplished by
M400=CX/D1=CY/D2=CZ/D3(4)
where M400is the magnification of an image displayed on each display segment400.

An optional criterion, for other embodiments, is shape preservation across display segments400W,1,400W,2, and400W,3at site W. For example, edge454of the table450at each of sites X, Y, and Z, should appear continuous across display segments400W,1,400W,2, and400W,3. Size and shape continuity is illustrated for the display segments100ofFIGS. 1-3inFIG. 2.

FIG. 5is a flowchart of a method500, according to another embodiment, of adjusting two or more cameras, e.g., cameras102ofFIG. 1, respectively corresponding to at least two displays, e.g., displays100ofFIG. 1. For one embodiment, displays100are located at a first site and cameras102at a second site remote from the first site. A table, such as table150ofFIG. 1, may also be located at the second site. In method500, cameras102are adjusted so that an image displayed by the displays100appears as a substantially continuous image, where sizes and distances are preserved across the displays100. For another embodiment, method500may be used to adjust cameras of a multipoint setup, e.g., as shown inFIG. 4, where the cameras, such as cameras402X,402Y, and402Z, are respectively located at different sites and respectively transmit images to display segments, such as display segments400W,1,400W,2, and400W,3, located at another site.

At block510, a first camera, such as camera1022, is set so that a dimension of its image field is substantially equal to a dimension of an object in the image field. For example, for one embodiment, this involves zooming camera1022so that a width of its image field is equal to a width of a table segment at the edge, as shown inFIG. 1. For one embodiment, widths of the table segments are marked by placing markers185, such as veneer strips or the like, on the table, as shown inFIG. 1. For example, the width of table segment1522at edge154may correspond to the distance between markers1852,1and1852,2(FIG. 1). Note that prior to zooming, camera1022may be panned so its optical axis1102substantially bisects the width of table segment1522at edge154of the table or the distance between markers1852,1and1852,2, as shown inFIG. 1.

Alternatively, camera1022may be zoomed so that a height of its image field is substantially equal to the height of an object placed on table segment1522at edge154. For some embodiments, cameras102have a fixed aspect (height-to-width) ratio, so that adjusting one dimension of the focal plane establishes the other dimension of the focal plane. For other embodiments, the height and width of the focal plane may be adjusted independently.

At block520, the first camera, e.g., camera1022, is focused. This involves bringing an object into focus and thereby establishes the location of focal plane1752. For example, to locate focal plane1752behind edge154of table segment1522(FIG. 1) at chair340(FIG. 3), an object located at chair340is brought into focus. For embodiments where focal plane1752coincides with edge154of table segment1522, an object placed on table segment1522at edge154is brought into focus during focusing. Alternatively, edge154of table segment1522may be brought into focus for another embodiment. For one embodiment, block510may involve adjusting camera1022so that the width cw,2of its focal plane1752is substantially equal to the width of table segment1522at edge154or the distance between markers1852,1and1852,2at edge154. For this embodiment, focusing camera1022may occur substantially concurrently with adjusting the width of focal plane1752and may involve an iterative process.

For one embodiment, an object is in focus when a contrast of the image field is at or exceeds a predetermined contrast. Contrast may be defined as a difference between the lightest and darkest areas of an image field. Contrast ratio is another way of describing the contrast and may be defined as the ratio of the maximum value of the dynamic range of an image to the minimum value of the dynamic range of the image. The contrast (or contrast ratio) may be determined from the darkest and lightest pixels of an image field for digital images. Alternatively, light pixels may be averaged and dark pixels may be averaged, and the contrast may be determined from these averages.

At block530, camera1022is set to capture a predetermined portion of an object, e.g., table segment1522or an object placed on table segment1522or on chair340(FIG. 3), and to orient, e.g., level, that portion of the object to a predetermined orientation within the image field. For example, for a table650shown inFIG. 6(a top view), tilting or tilting and rolling camera1022so that the near boundary plane3022of the region of useful image quality3002is at markers606and608disposed on an upper surface of table650accomplishes this for one embodiment. Note that the distance h′2,1between table edge654and marker606and the distance h′2,2between table edge654and marker608respectively correspond to vertical distances of table edge654above a bottom of a display.

Alternatively, the portion of the object that is visible in the image is determined by displaying the object on display segment1002or on a monitor screen, such as monitor display screen700inFIG. 7, while tilting or rolling and tilting camera1022so that intersections7102,1and7102,2of the image of table edge654and the vertical boundaries of monitor screen700are respectively at vertical distances h2,1and h2,2above the bottom of monitor screen700. Note that distances h2,1and h2,2respectively correspond to distances h′2,1and h′2,2ofFIG. 6. For another embodiment, the image of table edge654lies within a vertical distance from the bottom of monitor display screen700that is about 15 percent of the height of monitor display screen700.

Note that blocks510,520, and530, may be performed in various orders other than the order shown in the flowchart. Moreover, one or more of blocks510,520, and530, may be repeated. For one embodiment, the pan, tilt, roll, and zoom settings of camera1022may be stored after completing blocks510,520, and530.

At block540one or more second cameras, e.g., cameras1021and camera1023, are set to provide substantially the same magnification as camera1022. For one embodiment, a standard object is placed so that a portion thereof extends into the image field of camera1022and another portion extends into either the image field of camera1021or of camera1023, as shown inFIG. 1. For example, for one embodiment, the object, e.g., object190ofFIG. 1, may be placed at edge154of table150so that a portion extends onto table segment1522corresponding to camera1022and a portion extends onto either table segment1521corresponding to camera1021or onto table segment1523corresponding to camera1023. Then, either camera1021or1023is zoomed so that the image of the portion of object190captured by camera1021or1023that is displayed in the respective one of displays1001or1003used for monitoring or a monitor screen is substantially the same size as the image of the portion of object190captured by camera1022that is displayed in display1002or on a monitor screen.

Alternatively, for some embodiments, the distance between markers1852,1and1852,2corresponding to camera1022and the distance between markers1851,1and1851,2corresponding to camera1021are substantially equal, and the process described above in conjunction with block510is used to set a width of the image field of camera1021to be substantially equal to the distance between markers1851,1and1851,2. Note that this sets the magnifications of cameras1021and1022substantially equal. Note that substantially the same procedure can be used to set the magnification of camera1023substantially equal to that of camera1022.

Cameras1021and1023are focused at block550, e.g., according to the embodiments described above in conjunction with block520. That is, an object placed on table segment1521for camera1021(table segment1523for camera1023), such as at edge154, or behind table edge154is brought into focus. For one embodiment, the table edge154of table segment1521for camera1021(table segment1523for camera1023) is brought into focus at block550, meaning that focal plane1751(or focal plane1753) is located at edge154. For this embodiment, setting the magnification at block540and focusing at block550are performed substantially concurrently. For embodiments where the back edge of a table is straight and lies in substantially one plane, such as edge654of table650ofFIG. 6, cameras102may have the same or substantially the same focal distance f when focused.

For one embodiment, each of the cameras, i.e., the first camera and each of the one or more second cameras, may be focused before setting their magnifications. For another embodiment, setting the magnification of each camera and focusing that camera may be performed iteratively because focusing may change the magnification and vice versa. For example, the magnification may be set, followed by focusing, followed by checking the magnification, followed by resetting the magnification if the magnification changed, followed by checking the focus, followed by refocusing if the focus changed, followed by checking the magnification, and so on until the desired magnification and focus are achieved for each camera.

At block560, a separation distance between the focal planes of the cameras is set. For example, distance b1-2(FIG. 1) separating successively adjacent planes1751and1752and distance b2-3separating successively adjacent planes1752and1753are set. For one embodiment, panning or panning and rolling camera1021(or camera1023) accomplishes this. Specifically, for one embodiment, markers, such as markers185(FIG. 1), or objects disposed on the tabletop may be used to set the separation distance b. For example, with camera1022set up as described above in conjunction with blocks510,520, and530, an edge of its image field may be at an edge of marker1852,1, as shown inFIG. 1, or an edge of focal plane1752may be at an edge of marker1852,1(not shown) for embodiments where focal plane1752is at edge154. To set distance b1-2, camera1021is panned or panned and rolled so that an edge of its image field is at an edge of marker1851,2, as shown inFIG. 1, or an edge of focal plane1751is at an edge of marker1851,2(not shown) for embodiments where focal plane1751is at edge154. A similar procedure may be used to set distance b2-3.

At block570, cameras1021and1023are set so that portions of an object, such as a tabletop, captured thereby when displayed are aligned with a portion of that object captured by the first camera when displayed. This enables continuous lines, e.g., an edge of a table, portions of a person's anatomy, etc., segments of which are respectively captured by cameras102and displayed on display segments100, to appear substantially continuous across display segments100, as illustrated inFIG. 2. For one embodiment, this involves displaying different segments of the tabletop respectively captured by cameras102, e.g., on a continuous monitor screen or on segments of a segmented monitor screen, and adjusting cameras1021and1023so that the displayed tabletop segments corresponding thereto align (or conform) with the displayed tabletop segment corresponding to camera1022. Note that the displayed tabletop segment corresponding to camera1022is positioned as described above in conjunction with block530andFIGS. 6 and 7.

FIG. 8illustrates the display of tabletop segments8521,8522, and8523, according to another embodiment, respectively captured by cameras1021,1022, and1023on a monitor screen or on a display, such as display101ofFIG. 1, used for monitoring. The edge of the tabletop is straight so that edge thereof lies in a substantially single plane. Therefore, cameras1021and1023are tilted or tilted and rolled so that displayed edge segments8541and8543, respectively of tabletop segments8521and8523, are substantially colinear with displayed edge segment8542of tabletop segment8521. That is, cameras1021and1023are tilted or tilted and rolled so that displayed edge segments8541and8543are located at substantially the same distance above the bottom of the monitor screen as displayed edge segment8542. Note that the distance above the bottom of the monitor screen of displayed edge segment8542was set at block530.

FIG. 9illustrates tabletop segments9521,9522, and9523of a table950, respectively captured by cameras1021,1022, and1023, displayed on a monitor screen or on a display, such as display101ofFIG. 1as shown inFIG. 9, used for monitoring, according to another embodiment. Tabletop segment9522has an edge segment9542that includes portions9552,1and9552,2that are angled with respect to each other. Tabletop segments9521and9523respectively have straight edge segments9541and9543that respectively form angles with portions9552,1and9552,2of edge segment9542. Note that the shape of the edge of table950is similar to the shape of edge154of table150ofFIG. 1.

The respective vertical distances h2,1and h2,2of ends9102,1and9102,2of edge segment9542above the bottom of display segment1002are established by adjusting camera1022as described above in conjunction with block530. Camera1021(or camera1023) camera is rolled and tilted so that an end9101of edge segment9541is at the vertical distance h1above the bottom of display segment1001(or an end9103of edge segment9543is at the vertical distance h3above the bottom of display segment1003).

The vertical distances h1and h3are determined from vertical distances h2,1and h2,2, as follows: For one embodiment, portion9552,1(or portion9552,2) of edge segment9542is extended beyond end9102,1(or end9102,2), e.g., to midway between display segments1001and1002(or display segments1001and1003), as indicated by a dashed line9302-MP1(or a dashed line9302-MP2) inFIG. 9. This establishes a point9201-2(or a point9202-3), e.g., midway between display segments1001and1002(or between display segments1001and1003). The vertical distance h1(or h3) occurs, for example, at the intersection of the vertical edge of display segment1001corresponding to end9101of edge segment9541(or display segment1003corresponding to end9103of edge segment9543) and a dashed line940MP1-1(or dashed line940MP2-3) extending from point9201-2(or point9201-2) at the same slope as edge segment9541(or edge segment9543), as shown inFIG. 9.

For another embodiment, curve fits may be used to determine the vertical distances of ends2101and2103, respectively of edge segments2541and2543of table250ofFIG. 2, respectively from the bottoms of displays1001and1003. This is indicated by dashed line2301between the ends2101and2102,1respectively of edge segments2541and2542and by dashed line2303between the ends2102,2and2103respectively of edge segments2542and2543.

Note that blocks540,550,560, and570, may be performed in various orders other than the order shown in the flowchart. Moreover, one or more of blocks540,550,560, and570, may be repeated. For one embodiment, the pan, tilt, roll, and zoom settings of cameras1021and1023may be stored after completing blocks540,550,560, and570.

CONCLUSION

Although specific embodiments have been illustrated and described herein it is manifestly intended that the scope of the claimed subject matter be limited only by the following claims and equivalents thereof