Abstract: A three-dimensional data encoding method includes: generating first information in which an N-ary tree structure of a plurality of three-dimensional points included in three-dimensional data is expressed using a first formula, where N is an integer of 2 or higher; and generating a bitstream including the first information. The first information includes pieces of three-dimensional point information each associated with a corresponding one of the plurality of three-dimensional points. The pieces of three-dimensional point information each include indexes each associated with a corresponding one of a plurality of levels in the N-ary tree structure. The indexes each indicate a subblock, among N subblocks belonging to a corresponding one of the plurality of levels, to which a corresponding one of the plurality of three-dimensional points belongs.

Abstract: A display method is a display method performed by a display device that operates in conjunction with a mobile object, and includes: determining which one of first surrounding information, which is video showing a surrounding condition of the mobile object and is generated using two-dimensional information, and second surrounding information, which is video showing the surrounding condition of the mobile object and is generated using three-dimensional data, is to be displayed, based on a driving condition of the mobile object; and displaying the one of the first surrounding information and the second surrounding information that is determined to be displayed.

Abstract: A generation method is disclosed. Two-dimensional (2D) images that are generated by photographing a space from different viewpoints with at least one camera are obtained. Resolutions of the 2D images are reduced to generate first images, respectively. Second images are generated from the 2D images, respectively such that a resolution of each of the second images is higher than a resolution of any one of the first images. First three-dimensional (3D) points are generated based on the first images. The first 3D points indicate respective first positions in the space. A second 3D point is generated based on the second images. The second 3D point indicates a second position in the space. A 3D model of the space is generated based on the first 3D points and the second 3D point.

Abstract: A three-dimensional data encoding method includes encoding information of a current node included in an N-ary tree structure of three-dimensional points included in three-dimensional data, where N is an integer greater than or equal to 2. In the encoding, reference to information of a first node included in neighboring nodes spatially neighboring the current node is permitted, and reference to information of a second node included in the neighboring nodes is prohibited, the first node having a same parent node as the current node, the second node having a different parent node from the parent node of the current node.

Abstract: The steel material includes a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in Embodiment, wherein, in its microstructure, a total area fraction of ferrite and pearlite is 10.0% or more, and a proportion of a content of V (mass %) in electrolytic extraction residue to the content of V (mass %) in the chemical composition is 10.0% or less.

Abstract: A core portion of the carbonitrided bearing component includes a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in the embodiment of the present specification. A concentration of C of its surface is, in mass %, 0.70 to 1.20%, a concentration of N of the surface is, in mass %, 0.15 to 0.60%, a Rockwell C-scale hardness HRC of the surface is 58 to 65, and in the core portion, an area ratio of an area of coarse V-based precipitates to a total area of V-based precipitates is 15.0% or less.

Abstract: A three-dimensional model distribution method includes: distributing a first model, which is a three-dimensional model of a target space in a target time period, in a first distribution mode; and distributing a second model, which is a three-dimensional model of the target space in the target time period and makes a smaller change per unit time than the first model, in a second distribution mode different from the first distribution mode.

Abstract: A display method is a display method performed by a display device that operates in conjunction with a mobile object, and includes: determining which one of first surrounding information, which is video showing a surrounding condition of the mobile object and is generated using two-dimensional information, and second surrounding information, which is video showing the surrounding condition of the mobile object and is generated using three-dimensional data, is to be displayed, based on a driving condition of the mobile object; and displaying the one of the first surrounding information and the second surrounding information that is determined to be displayed.

Abstract: A video display method includes: selecting, as a first selected viewpoint, one first viewpoint from among a plurality of first viewpoints corresponding to a plurality of second videos, and displaying a second video corresponding to the first selected viewpoint; determining whether the first selected viewpoint is included in a plurality of second viewpoints corresponding to a plurality of fourth videos captured after the plurality of second videos; and selecting one second viewpoint from among the plurality of second viewpoints as a second selected viewpoint and displaying a fourth video that is included in the plurality of fourth videos and corresponds to the second selected viewpoint, when the first selected viewpoint is determined to not be included in the plurality of second viewpoints.

Abstract: A three-dimensional data encoding method includes: determining whether to encode, using an octree structure, a current space unit among a plurality of space units included in three-dimensional data; encoding the current space unit using the octree structure, when it is determined that the current space unit is to be encoded using the octree structure; encoding the current space unit using a different method that is not the octree structure, when it is determined that the current space unit is not to be encoded using the octree structure; and appending, to a bitstream, information that indicates whether the current space unit has been encoded using the octree structure.

Abstract: A three-dimensional model processing method includes: generating, from first images shot by respective cameras at a first time, a first three-dimensional model including: first three-dimensional points indicating a subject at the first time; and first camera parameters indicating positions and orientations of the cameras; generating, from second images shot by the respective cameras at a second time, a second three-dimensional model including: second three-dimensional points indicating the subject at the second time; and second camera parameters indicating positions and orientations of the cameras; detecting a stationary camera among the cameras, whose position and orientation has not changed between the first and second times, or stationary three-dimensional points among the three-dimensional points, whose positions have not changed between the first and second times; and matching world coordinate systems of the first and second three-dimensional models, based on the first camera parameters of the stationary

Abstract: A three-dimensional data encoding method includes encoding information of a current node included in an N-ary tree structure of three-dimensional points included in three-dimensional data, where N is an integer greater than or equal to 2. In the encoding, reference to information of a first node included in neighboring nodes spatially neighboring the current node is permitted, and reference to information of a second node included in the neighboring nodes is prohibited, the first node having a same parent node as the current node, the second node having a different parent node from the parent node of the current node.

Abstract: A calibration apparatus calibrates parameters of imaging apparatuses which are disposed at different positions and image a common three-dimensional space. The calibration apparatus includes: an obtaining circuit which obtains videos captured by the imaging apparatuses and each including frames; an extraction circuit which extracts feature points from the frames included in the videos, the feature points including first feature points extracted from first frames included in the videos and second feature points extracted from areas containing an image of a moving object in second frames included in the videos and different from the first frames; a matching circuit which performs matching using the feature points, the matching including matching between the first feature points and matching between the second feature points; and a calibration circuit which calculates parameters of the imaging apparatuses based on first matching results obtained through the matching by the matching circuit.

Abstract: A calibration method of calibrating, using a processor, parameters of a plurality of imaging apparatuses that capture a common three-dimensional space, includes: obtaining images captured by the plurality of imaging apparatuses; obtaining the parameters of the plurality of imaging apparatuses; for each of the images, generating at least one search window to extract a plurality of feature points of the image using the parameters; for each of the images, extracting the plurality of feature points from an inside of the at least one search window; performing feature point matching between the images using the plurality of feature points; and calibrating the parameters based on a plurality of matching results obtained.

Abstract: A three-dimensional data encoding method includes: extracting, from first three-dimensional data, second three-dimensional data having an amount of a feature greater than or equal to a threshold; and encoding the second three-dimensional data to generate first encoded three-dimensional data. For example, the three-dimensional data encoding method may further include encoding the first three-dimensional data to generate the second encoded three-dimensional data.

Abstract: An image display method includes receiving an integrated image in which low-resolution images of a scene from different viewpoints are arranged, displaying the integrated image such that a low-resolution image among the low-resolution images is displayed in a first size, receiving a high-resolution image having a same viewpoint as the low-resolution image, the high-resolution image having a higher resolution than the low-resolution image, displaying the high-resolution image in a second size larger than the first size, and displaying the low-resolution image in a third size larger than the first size after the integrated image is displayed and before the high-resolution image is displayed in the second size.

Abstract: A three-dimensional data encoding method includes: determining whether to encode, using an octree structure, a current space unit among a plurality of space units included in three-dimensional data; encoding the current space unit using the octree structure, when it is determined that the current space unit is to be encoded using the octree structure; encoding the current space unit using a different method that is not the octree structure, when it is determined that the current space unit is not to be encoded using the octree structure; and appending, to a bitstream, information that indicates whether the current space unit has been encoded using the octree structure.

Abstract: A three-dimensional data encoding method includes: extracting, from first three-dimensional data, second three-dimensional data having an amount of a feature greater than or equal to a threshold; and encoding the second three-dimensional data to generate first encoded three-dimensional data. For example, the three-dimensional data encoding method may further include encoding the first three-dimensional data to generate the second encoded three-dimensional data.

Abstract: A three-dimensional reconstruction method includes: reconstructing a first three-dimensional model from a first multi-viewpoint image obtained by shooting a real space, and reconstructing a second three-dimensional model from a second multi-viewpoint image obtained by shooting the real space at a different time; and matching world coordinate systems of the first three-dimensional model and the second three-dimensional model.

Abstract: An image display method includes displaying an integrated video in which videos of a scene from different viewpoints are arranged in a frame, the videos including at least one real video and at least one virtual video generated from the at least one real video. A first user interface into which a first operation is input is displayed. Viewpoints of the displayed videos are changed according to the first operation. A second user interface into which a second operation is input is displayed. A playing speed of the displayed videos is changed according to the second operation.