Abstract: A filter wheel having spirally shaped left and right channel 3D filters. The 3D filters are, for example, spectral separation filters. The filter is mounted, for example, close to an integrating rod output of a projector. The left and right channel filtered light scrolls across a modulation device which is energized with correspondingly scrolling left and right image data. In one embodiment, the integrating rod comprises mirrored surfaces to facilitate recycling of light reflected off the filter wheel. The filter wheel may be placed in a single or dual projector configuration. In one embodiment, the filters are fixed at the end of an integrating rod using “re-cycled” light to illuminate different channels of a projection system.

Abstract: A stereoscopic image display apparatus according to an embodiment includes: a display device including a display panel including pixels, and an optical plate controlling light rays emitted from pixels; a camera provided in the display device; a face tracking unit making a decision whether a viewer exists in front of the display device based on an image picked up by the camera, and if the viewer exists, sampling and detecting a distance from the display device to the viewer and a position of the viewer; a memory storing the position of the viewer sampled and detected by the face tracking unit; and an image display control unit estimating the position of the viewer based on the position of the viewer stored in the memory and driving and controlling the display panel on based on the estimated position, when the face tracking unit does not recognize that the viewer exists.

Abstract: The present invention discloses a stereoscopic image display system and a method of controlling the same. An eye tracking module locates current 3D spatial positions of the viewer's eyes, and generates the information of both left and right eyes' current 3D spatial positions. A control module controls a display device that can alter the direction of the light outputted, and outputs images on the display device in time multiplex mode. The light containing the left eye image is outputted to the position of left eye instead of right eye at one time point, and the light containing the right eye image is outputted to the position of right eye instead of left eye at another time point, so that a stereoscopic image is perceived according to the parallax theory. The present invention enlarges the visual range of stereoscopic image and achieves a better stereoscopic image visual experience for viewers.

Abstract: Spectral separation filters for channels of a 3D image projection incorporate passbands of primary colors. In at least one of the filters, passbands are present in more than 3 primary colors. A set of two filters include a first filter having passbands of low blue, high blue, low green, high green, and red, and a second filter having passbands of blue, green, and red. The additional primary passbands of the first filter allow for an increased color space in projections through the filters compared to filters only having red, green, and blue primaries. The added flexibility of the increased color space is utilized to more closely match a color space and white point of a projector in which the filters are used.

Abstract: A projection apparatus has a first light beam having a first state of polarization and containing a first set of primary colors, a first light modulator arrangement for spatially modulating the polarization state of the first light beam to encode a first image thereon in the first set of primary colors, a second light beam having a second state of polarization and containing a second set of primary colors, and a second light modulator arrangement for spatially modulating the polarization state of the second light beam to encode a second image thereon. A polarizing beam splitter having first and second input ports to admit the first and second encoded light beams. Light of one polarization state incident on the first port is transmitted to the output port and light of another polarization state incident on the second port is reflected to said output port so that said transmitted and reflected light is combined into a common output beam at said output port.

Abstract: It is made possible to provide a three-dimensional image display device by which an alarm image with high visibility can be displayed at the end of the viewing zone in a parallel-ray one-dimensional IP system, without a reduction of the viewing zone or a decrease in processing speed.

Abstract: A method and system for displaying an image in three dimensions during a frame period. The method includes generating a left image sub-frame and a right image sub-frame. The left image sub-frame defines a visual perspective of a left eye and the right image sub-frame defines a visual perspective of a right eye for the image. The method further includes displaying the left image sub-frame utilizing a first plurality of colors and displaying the right image sub-frame utilizing a second plurality of colors. The first plurality of colors is distinct from the second plurality of colors.

Abstract: Spectacles are disclosed for use in viewing images or videos, and include at least two lenses each having an adjustable optical property and an image capture device associated with the spectacles for receiving a digital image comprising a plurality of digital image channels each containing multiple pixels. The spectacles further include the image capture device for capturing a digital image and a processor for computing a feature vector from pixel values of the digital image channels wherein the feature vector includes information that would indicate whether the image is an anaglyph or a non-anaglyph image.

Abstract: A method of operation of three dimensional (3D) stereoscopic television consistent with certain implementations involves turning on or installing a set of 3D glasses on a viewer to cause the set of 3D glasses to enter an active operational mode; and at the 3D glasses, emitting a signal to the television that causes the television to switch from a 2D display mode to a 3D display mode. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

Abstract: A method includes reducing a red rivalry through adjusting a color temperature on a first image, converting the first image from the RGB domain to a YCbCr domain, shifting a hue of a red color in the first image towards a magenta color to reduce a red color vibrancy, and adjusting a blue color in the first image such that a dark blue visible through a second lens corresponding to a second image is at least partially visible through a first lens corresponding to the first image. The method also includes reducing the red rivalry through adjusting a tone of the red color in the first image towards a brown color, converting the first image from the YCbCr domain back to the RGB domain, adjusting a color saturation in the first image, and combining the first image with the second image in a processor to generate an anaglyph image.

Abstract: A display apparatus including a first insulating substrate, a plurality of pixels, a second insulating substrate, a color filter layer, and a pattern retarder. The first insulating substrate includes a plurality of pixel areas arranged in an array of rows and columns, which has a length in the row direction longer than a length in the column direction, and has a length in a row direction longer than a length in a column direction. The pixels are arranged in the pixel areas, respectively, to display a 2D image and a 3D image. Among the pixels, first to fourth pixels successively arranged in the column direction define a unit pixel that displays one color information, and the fourth pixel corresponds to the white color pixel.

Abstract: A metadata generating method including: receiving sub-region dividing information to divide an object into a plurality of sub-regions; and generating sub-region indicating information to indicate each of the plurality of sub-regions divided according to the sub-region dividing information.

Abstract: The present invention relates to a polarized stereoscopic display method and a device thereof. In one embodiment, the device comprises a first signal processing part for signal processing the first image and producing a first input image that is input to a first projector so that a first output beam output from the first projector corresponding to the first image is output from the first projector with a 90 degree phase difference with respect to a second output beam outputted from the second projector corresponding to the second image. The first signal processing part may comprise an image rotating part for rotating an inputted image by 90 degree, a resizing part combined with an output terminal of the image rotating part for resizing the image rotated by 90 degree corresponding to a screen and output it to the first projector.

Abstract: A method for processing an anaglyph image to produce an enhanced image is described. The method includes receiving an anaglyph image; determining first and second feature locations from the first and second digital image channels and producing feature descriptions of the feature locations; and using the feature descriptions to find feature point correspondences between the first and second feature locations of the first and second digital image channels. The method further includes determining a warping function for the second digital image channel based on the feature point correspondences; producing an enhanced second digital image channel by applying the warping function to the second digital image channel; and producing an enhanced image from the first digital image channel and the enhanced second digital image channel.

Abstract: Methods are disclosed for supporting stereo 3D video in computing devices. A computing device can receive stereo 3D video data employing a YUV color space and chroma subsampling, and can generate anaglyph video data therefrom. The anaglyph video data can be generated by unpacking the stereo 3D video data to left and right views and combining the left and right views into a single view via matrix transformation. The combining uses transform matrices that correspond to a video pipeline configuration. The transform matrix coefficients can depend on characteristics of the video pipeline components. Modified transform matrix coefficients can be used in response to changes in the video pipeline configuration. Video encoded in stereo 3D video data can be selected to be displayed in stereo 3D, anaglyph or monoscopic form, depending on user input and/or characteristics of video pipeline components.

Abstract: A method of displaying a stereoscopic image provides first light having a first wavelength and second light having a second wavelength different from the first wavelength to the a display panel according to left-eye and right-eye images displayed on the display panel. Color correcting data are generated by correcting at least one of left-eye color data corresponding to the left-eye image and right-eye color data corresponding to the right-eye image such that a first color coordinate according to the first light and a second color coordinate according to the second light coincide with each other with respect to the same color. The left-eye and right-eye images are displayed using light having wavelengths different from each other, so that a display quality of the stereoscopic image may be enhanced.

Abstract: A display device includes: a two-dimensional display unit that displays p viewpoint videos, which are spatially divided, within one screen; and an optical device that optically splits the p viewpoint videos displayed on the display unit so as to enable a stereoscopic view at p viewpoints. The display unit includes unit pixels each formed from sub-pixels that display r types of colors necessary for a color video display, and the sub-pixels that emit light of different colors are arranged so as to be adjacent to each other in a same row in a screen horizontal direction. Each of the p viewpoint videos is displayed in n sub-pixel rows, each of which is configured by the sub-pixels aligned in a first direction other than the screen horizontal direction and which are consecutive in the screen horizontal direction, in the screen horizontal direction on a cycle of (p×n) rows.

Abstract: An apparatus and method for stereoscopic 3D image projection and viewing using a single projection source, alternating polarization, and passive eyewear. This approach is applicable to frame sequential video created using existing 3D graphics APIs, as well as other video signal formats, and is compatible with existing digital light processor (DLP) technology for both front and rear projection systems. A alternating polarizer filter actuator in the form of a closed feedback loop with pulse width modulated control is used to modulate the projected image. A preferred embodiment enables an existing DLP projection system to be enhanced with 3D capability.

Abstract: A display device includes: a display unit that composes p (here, p is an integer equal to or greater than two) viewpoint videos that are spatially divided within one screen by sequentially displaying q (here, q is an integer that is equal to or greater than two and is equal to or less than p) display patterns that are divided in time; and an optical separation device that optically separates the p viewpoint videos configuring each one of the q display patterns displayed on the display unit.

Abstract: When an end portion of a three-dimensional image appears to pop forward from a display surface, a predetermined end area is set at a periphery of images forming the three-dimensional image to modify at least one of the images to modify the stereoscopic effect so that at least a part of the end portion appears to be level with the display surface. A disparity between corresponding pixels in the end area of the images is modified so that the disparity is gradually decreased toward the end of the images, and image parts at left and right areas of the end area of a reference image among the images are deformed based on the disparity. At least one of the images is modified by modifying the image other than the reference image with the deformed image parts of the end area. Then, three-dimensional processing is applied to the modified images.

Abstract: A system for producing a three dimensional (3D) effect from displayed images is provided. Images of a video program are displayed in a complementary primary colors-encoded stereoscopic image format, which includes stereoscopic images of objects or a scene. Corresponding stereoscopic images are displayed in different colors. As the display refreshes, the display alternates the colors of the corresponding stereoscopic images and sends a control signal to active glasses worn by a viewer of the video program that causes a left-eye lens and right-eye lens filter to alternate the color which is filtered in by the respective filter. The viewer is able to view the video program with a perceived 3D effect without either of the lenses of the active glasses having to become opaque during display of the complementary primary colors-encoded stereoscopic image.

Abstract: The invention relates to a method of and apparatus for displaying a holographically generated video image having plural video frames. For each frame there is provided and computed (20) a respective sequential plurality of holograms. Each said sequential plurality of holograms of the plural video frames are sequentially displayed on a diffractive element (12) for viewing the replay field thereof, and the noise variance of each frame is perceived as attenuated by averaging across said plurality of holograms.

Abstract: A stereoscopic display apparatus includes a display having pixels arrayed in a longitudinal direction and a lateral direction to form a matrix, each pixel including sub-pixels with color components, and a control element opposed to the display and having linear openings extending in the longitudinal direction and arrayed in the lateral direction. The openings of any two sub-pixels adjacent in the lateral direction always overlap regardless of a position in the lateral direction. The sum of the longitudinal components of the opening ratios of s adjacent in the lateral direction is constant.

Abstract: A method for analyzing an image to determine if it is an anaglyph image is disclosed. The method includes receiving a digital image including a plurality of digital image channels each containing multiple pixels; using a processor to compute a feature vector from pixel values of the digital image channels wherein the feature vector includes information that would indicate whether the image is an anaglyph or a non-anaglyph image; classifying the digital image as either an anaglyph or as a non-anaglyph based on the feature vector; and storing the classification of the digital image.

Abstract: A processor adjusts a first image generated by a projector and a second image generated by the projector in a first manner if the first and second images together include a stereoscopic image, and in a second manner if the first and second images do not include a stereoscopic image.

Abstract: A method includes reducing a red rivalry through adjusting a color temperature on a first image, converting the first image from the RGB domain to a YCbCr domain, shifting a hue of a red color in the first image towards a magenta color to reduce a red color vibrancy, and adjusting a blue color in the first image such that a dark blue visible through a second lens corresponding to a second image is at least partially visible through a first lens corresponding to the first image. The method also includes reducing the red rivalry through adjusting a tone of the red color in the first image towards a brown color, converting the first image from the YCbCr domain back to the RGB domain, adjusting a color saturation in the first image, and combining the first image with the second image in a processor to generate an anaglyph image.

Abstract: A multiple path stereoscopic projection system is disclosed. The system comprises a polarizing splitting element configured to receive image light energy and split the image light energy received into a primary path and a secondary path, a reflector in the secondary path, and a polarization modulator or polarization modulator arrangement positioned in the primary path and configured to modulate the primary path of light energy. A polarization modulator may be included within the secondary path, a retarder may be used, and optional devices that may be successfully employed in the system include elements to substantially optically superimpose light energy transmission between paths and cleanup polarizers. The projection system can enhance the brightness of stereoscopic images perceived by a viewer. Static polarizer dual projection implementations free of polarization modulators are also provided.

Abstract: A multi-spectral stereoscopic display system with additive and subtractive techniques is disclosed. Stereographic images may be presented and viewed via two sets of spectral bands that may have low or no overlap with each other. The color balances of a left-eye image and a right-eye image may be almost matching or identical. The left-eye image and the right-eye image may each be a full-color image with neutral color balance, even without modifying the color balance of original image content. Additive and subtractive techniques may provide spectral content within these sets of spectral bands. Subtractive techniques may include spectral filters. Additive techniques may include multi-spectral illuminants. An arrangement of a set of spectral bands may correspond to natural resonant characteristics. The spectral bands may be determined independently of conventional RGB designation of spectral bands.

Abstract: A multi-spectral stereoscopic display system is disclosed. A left-eye image may be presented and viewed via a first set of spectral bands. A right-eye image may be presented and viewed via a second set of spectral bands. The two sets of spectral bands may have low or no overlap with each other. The color balances of the left-eye image and the right-eye image may be almost matching or identical. The left-eye image and the right-eye image may each be a full-color image with neutral color balance, even without modifying the color balance of original image content. Thin-film optical interference filters may provide pass-bands corresponding to these sets of spectral bands. The filter design may lead to an inexpensive viewing apparatus that can be mass-produced using inexpensive glass or polymer substrates. This system does not rely on polarization techniques and may be used with a white or metallic display screen.

Abstract: A method of presenting multiple image sources of approximately registered images so that the mind can easily fuse the multiple images into one image. Improvement to fusing can be achieved by alternating views between sources at 85 hertz or more. The insertion of a black frame between the succession of frames optimizes the neurological functions of the human optical system (produces retinal decay) such that the perception of a useful fused image is greatly enhanced. Stereographic fusion can also be achieved to allow for fusion of loosely registered datasets.

Abstract: A calibration apparatus which estimates a calibration parameter of an image acquisition apparatus, comprises a calibration jig which includes at least two planes and in which calibration markers having known three-dimensional positions are arranged in each plane based on a predetermined rule. The calibration apparatus further comprises a calibration marker recognition section configured to measure and number in-image positions of the calibration markers in at least one image obtained by photographing the calibration jig by the image acquisition apparatus, and a parameter estimate section configured to estimate the calibration parameters of the image acquisition apparatus by the use of the three-dimensional position and the in-image position of the calibration markers numbered by the calibration marker recognition section.

Abstract: A multiple path stereoscopic projection system is disclosed. The system comprises a polarizing splitting element configured to receive image light energy and split the image light energy received into a primary path and a secondary path, a reflector in the secondary path, and a polarization modulator or polarization modulator arrangement positioned in the primary path and configured to modulate the primary path of light energy. A polarization modulator may be included within the secondary path, a retarder may be used, and optional devices that may be successfully employed in the system include elements to substantially optically superimpose light energy transmission between paths and cleanup polarizers. The projection system can enhance the brightness of stereoscopic images perceived by a viewer. Static polarizer dual projection implementations free of polarization modulators are also provided.

Abstract: In one aspect, the present invention relates to a stereoscopic projection system including a projection device with at least one filter which filters a parameter of the light in a color selective manner. The at least one filter which filters a parameter of the light in a color selective manner has a spectral characteristic for transmitting light in a first wavelength band or set of wavelength bands and for reflecting light in a second wavelength band or set of wavelength bands. The projection device includes a device, such as e.g. a rotating wheel or a sliding filter, for fast synchronized switching between light in different wavelength bands or sets of wavelength bands.

Abstract: The invention relates to systems for performing color stereoscopic images and can be used for creating stereoscopic computer monitors and TV sets. A technical result consists in performing a color stereoscopic image with high sharpness without geometric distortions, with a maximum of resolution and a wide field of vision.

Abstract: A method of combined exchange of image data and related depth data is disclosed. The method comprises: converting an input image signal, representing the image data, comprising a predetermined number of input color components (R,G,B) into an output image signal comprising a luminance component and a chrominance component; combining the output signal with the related depth data into a combined signal, comprising the luminance component, the chrominance component and a depth component (D) which is based on the depth data; and transmission of the combined signal over a number of channels (108-112) which is equal to the predetermined number of input color components (R,G,B).

Abstract: Encoding left and right eye stereoscopic image pairs into a color coded ‘anaglyph’ image allows for 3-D viewing through colored eyewear. The color mapping may be tailored locally to specific eyewear and display hardware and generates anaglyph output from distributed full-color left and right eye stereoscopic data. In an exemplary embodiment, determination of eyewear may involve viewer interaction through visual inspection of displayed calibration images or by other means. Left and right eye data may be mapped onto high quality anaglyph images. The overall approach attempts to provide a consistent, good quality stereoscopic experience for different displays and eyewear.

Abstract: A liquid crystal display module, a liquid crystal display device, and a method for assembling the liquid crystal display device, which are capable of minimizing the overall size of the liquid crystal display device by improving an engaging structure between the liquid crystal display module and a case, are disclosed. Engaging holes are formed in an unused region of a top chassis, a mold frame and an end portion of a back cover. One side of a shaft screw is engaged with a catching member integrally formed with the inner side upper surface of a case. The other side of the shaft screw penetrates through the engaging holes of the top chassis, the mold frame, and the back cover and is engaged with a nut screw on a rear surface of the back cover. Accordingly, a separate space for installing a fixing member for fixing the mold frame and the back cover to the case is not needed, and the case, the mold frame, and the back cover is not engaged by using a separate screw.

Abstract: Four primary colors may be used to render anaglyphs with wide color gamuts. The first image of a stereoscopic pair may be rendered in three primary colors while the second image of a stereoscopic pair may be rendered in a fourth primary color. Retinal rivalry may be avoided in an anaglyph by balancing the brightness contrasts of the first and second images for like subject matter. The retinal rivalry may be measured and controlled in anaglyphs by selecting values of a retinal rivalry color coordinate.

Abstract: Four primary colors provide a wide color gamut in the anaglyph images. Primary colors with narrow spectral distributions allow the first and second images in an anaglyph to be viewed using colored filter glasses. In print media, primary colors with narrow spectral distributions are provided by fluorescent inks and incident light with narrow spectral distributions. Incident light with narrow spectral distributions may cooperate with broad adsorption spectra of inks to produce reflected light with narrow spectral distributions from printed anaglyphs. Viewing filters for anaglyphs comprised of narrow spectral distributions may have broad, overlapping transmission spectra and utilize adsorption dyes or pigments.

Abstract: A system for enabling depth perception of image content in a rendered composite image, wherein illuminant/colorant depth discrimination encoding provides encoding of first and second source images in a composite image, for the purposes of subsequent illuminant/colorant depth discrimination decoding. Composite image rendering allows for rendering the composite image in a physical form. Illuminant/colorant depth discrimination decoding allows recovery of the first and second source images, thus offering to an observer the perception of spatial disparity between at least one of the recovered source images and some or all of the remaining image content perceived in the rendered composite image.

Abstract: A method for enabling viewing of stereoscopic images is provided. The method includes providing a two dimensional image representation to a service bureau configured to convert the two dimensional image representation into a stereoscopic image and transmitting the enhanced image from the service bureau to an entity for purposes of displaying the images in a user desired configuration, such as in a digital photo frame. Alternately, the present design includes receiving a two dimensional electronic image representation in electronic form together with conversion criteria, converting the two dimensional electronic image representation into a stereoscopic image based on the conversion criteria, and providing the stereoscopic image to a user for display.

Abstract: A device used in projecting stereoscopic images is provided. The device includes an illumination source configured to transmit light energy in multiple sections or segments, each section or segment having an optical attribute associated therewith, such as a color (red, green, blue). The illumination source may include light emitting diodes or light projected through a “color wheel,” and light energy is polarized by the illumination source. At least two adjacent sections of the have identical optical attributes, such as identical colors, and different perspective views associated therewith. Different polarization attributes or polarization axis orientations may be employed to facilitate stereoscopic image transmission using linear, circular, and achromatic circular polarization. Polarization and viewing of polarized light energy may be addressed by occlusion using eyewear.

Abstract: A method for inspecting a substrate for defects, including: (a) obtaining an inspected pixel and a reference pixel; (b) calculating an inspected value and a reference value, the inspected value representative of the inspected pixel and the reference value representative of the reference pixel; (c) selecting a threshold in response to a selected value out of the inspected value and the reference value; and (d) determining a relationship between the selected threshold, the reference value and the inspected value to indicate a presence of a defect.

Abstract: A multi-mode stereoscopic image display method and apparatus wherein a plane picture and a stereoscopic picture can be displayed on a single display device. In the method and apparatus, video signals obtained by photographing an object at different angles are displayed on a display unit and a mode signal for assigning a stereoscopic mode or a plane mode is generated. In a stereoscopic mode, a picture displayed on the display unit is separated into a left-eye picture and a right-eye picture being incident to the left eye and the light eye of an observer. In a plane mode, said picture displayed on the display unit is transmitted to the observer without change.

Abstract: An apparatus is provided to produce a real-time anaglyph, comprising a graphics engine, a memory and an anaglyph generator. The graphics engine provides a sync signal and generates a left eye image and a right eye image in accordance with a horizontal offset calculated from a 3D graphic animation, wherein the horizontal offset between the left and the right eye images creates illusion of depth. The left eye image and the right eye image are temporarily stored in the memory. The anaglyph generator then fetches the left eye image and the right eye image from the memory in response to the sync signal, for producing a filtered left image and a filtered right image. As such, each filtered image is respectively tinted with one of the complementary colors. By viewing through a pair of anaglyph glasses, the filtered left and the filtered right images can thus create perception of depth.

Abstract: A telecommunications system includes a conferencing server (104, 106), a recording server (114) operably coupled to the conferencing server; and one or more telecommunications clients (110). The telecommunications clients (110) can use the conferencing server to supervise conversations between two or more of the parties. The recording server (114) is used to record conversations among the parties and store them as one or more digital files. The telecommunications clients (110) may further be provided with user interfaces (112) that allow control of the recording server (114) for real-time playback during a conversation. The user interface allows the user to control backup; normal speed forward; fast forward; back to beginning; and go to end (i.e., back to real-time output for the call).

Abstract: This invention relates to a stereo imaging system for use in telerobotic systems. A method of imaging a target site in a stereo imaging system is provided. The method typically includes capturing a right and a left optical image of the target site and transforming the right and the left optical images preferably into digital information. The method further includes converting the digital information into opposed images of the target site displayed on a stereo display of the stereo imaging system, one of the opposed images being associated with the right optical image and the other of the opposed images being associated with the left optical image. The method further includes regulating the digital information to cause the positions of the target site displayed on the opposed images to change relative to each other.

Abstract: An apparatus for controlling a stereo video display with non-stereo video source includes a memory, a read/write controller and a motion analyzer. The memory stores a current frame, a previous frame of the current frame, and a next frame for the current frame that is in preparation. The current frame and the previous frame are for a dextral image and a sinistral image of a stereoscopic image respectively. The read/write controller controls the addresses to write the current frame and the next frame into the memory, and the reading order of the current frame and the previous frame.

Abstract: Three-dimensional color images are produced by combining the red image plane from a left color camera and the blue and green image planes from a right color camera. Techniques for compensating for over or underexposure in a particular image plane are deployed as well as techniques for minimizing subjective disturbance when viewing relatively pure color regions of a 3-dimensional image and for transmission of 3-dimensional color television images to users.

Abstract: The present invention is a fully functional hand held computer having a see through display. An external viewing arrangement, such as a monocular scope, is used to view the operator's immediate surroundings. Optical images from the scope are superimposed with digital images from a miniature computer display. The resultant image allows the operator to look through the device and view his surrounding while simultaneously viewing and operating the software based applications. The entire device is held like a pair of binoculars and mouse like controls are located adjacent the operator's gripping position.