Abstract: In one embodiment, a method includes accessing a magnetic-field map of a region comprising data that represents magnetic-field values that correspond to locations in the region. The method includes accessing a sample magnetic recording comprising data that represents a time or distance series of magnetic measurements made along a path in the region. The method includes at least approximately aligning the sample magnetic recording to the magnetic-field map. Based on the alignment, the method includes generating a first set of parameters for aligning subsequent magnetic recordings to the magnetic-field map across a substantial entirety of the magnetic-field map, and generating one or more second sets of parameters for aligning subsequent magnetic recordings in one or more subdivisions of the magnetic-field map. The method also includes associating the first and second sets of parameters with the magnetic-field map and providing the magnetic-field map with the associated parameters for subsequent navigation.

Abstract: In one embodiment, an apparatus includes a first magnetometer that measures a magnetic induction and direction of a magnetic field. The first magnetometer has a first coordinate frame that includes a first x axis, a first y axis, and a first z axis. The apparatus includes a second magnetometer that measures the magnetic induction and direction of the magnetic field. The second magnetometer has a second coordinate frame that includes a second x axis, a second y axis, and a second z axis. Each of one or more of the second x axis, the second y axis, or the second z axis is has a predetermined orientation relative to the first x axis, the first y axis, or the first z axis.

Abstract: In one embodiment, a method includes accessing a trajectory and comparing a first one of multiple portions of the trajectory with a second one of the portions. A greater level of confidence is associated with the first one of the portions than the second one of the portions. The method includes determining, based on the comparison, that the first and second ones of the portions approximately magnetically coincide with each other and are not approximately colocated with each other in the trajectory; comparing a first level of confidence associated with the first one of the portions with a second level of confidence associated with the second one of the portions; and, when the first level of confidence is greater than the second level of confidence, adjusting the second one of the portions to be approximately colocated with the first one of the portions in the trajectory.

Abstract: In one embodiment, a method includes accessing an image file that includes a magnetic map with normalized magnetic-field values that each correspond to one of a plurality of locations in an area. The image file includes a first matrix with first elements, one or more of which each represent color values, and a second matrix with second elements, one or more of which each represent the normalized magnetic-field values. The image file also includes pixels, wherein each pixel corresponds to one of the locations, includes links to one or more of the first elements, and includes links to one or more of the second elements that represent the normalized magnetic-field values that correspond to the location that the pixel corresponds to. The method also includes performing navigation or localization using the magnetic map.

Abstract: In one embodiment, a method includes at a mapping server receiving from a plurality of regional servers a plurality of regional magnetic data sets; at the mapping server updating a geomagnetic map with one or more of the regional magnetic data sets, wherein the geomagnetic map comprises one or more of the geographic regions; and from the mapping server communicating one or more portions of the geomagnetic map as updated to one or more of the regional servers for distribution as geomagnetic map information to one or more of the magnetic navigation devices for localization or navigation.

Abstract: In one embodiment, a method includes, by an electronic device, accessing a first series of first magnetic values that represents a first magnetic recording that comprises a first set of first magnetic measurements that are each represented by one of the first magnetic values. The method includes, by the electronic device, accessing a second series of second magnetic values that represents a second magnetic recording that comprises a second set of second magnetic measurements that are each represented by one of the second magnetic values. The method includes, by the electronic device, approximately aligning the first and second series with each other; calculating a difference between the first and second series as aligned with each other; determining a similarity between the first and second series based on the difference; and performing navigation or localization based on the determined similarity.

Abstract: In one embodiment, a method includes accessing a magnetic map of an area that includes magnetic-field values for locations in the area. The method also includes accessing an image file that includes pixels that correspond to the locations and include components. The image file also includes a first matrix with elements that each include color values. The components of the pixels include links to elements in the first matrix. The method also includes embedding portions of the magnetic map into the image file by generating a second matrix for the image file including elements that represent the magnetic-field values and, for the locations in the area, writing to the components of the pixels corresponding to the locations links to elements of the second matrix. The method also includes communicating the image file, with the portions of the magnetic map embedded in it, to computing devices for navigation or localization.

Abstract: In one embodiment, a method includes accessing a first series of first magnetic values that represents a first magnetic recording that includes a first set of first magnetic measurements. Each of the first magnetic values represents one of the first magnetic measurements. The method includes accessing a second series of second magnetic values that represents a second magnetic recording that includes a second set of second magnetic measurements. Each of the second magnetic values represents one of the second magnetic measurements. The method includes approximately aligning the first and second series with each other; calculating a difference between the first and second series as aligned with each other; and determining a similarity between the first and second series based on the difference.

Abstract: In one embodiment, a method includes accessing a series of magnetic values measured by a magnetic-measurement device over a predetermined period of time. Each of the magnetic values corresponds to a location of the magnetic-measurement device during the predetermined period of time. The method includes, based on the series of magnetic values, determining that the location or orientation of the magnetic-measurement device did not substantially change during the predetermined period of time.

Abstract: In one embodiment, a method includes accessing a first series of first magnetic values that represents a first magnetic recording that includes a first set of first magnetic measurements. Each of the first magnetic values represents one of the first magnetic measurements. The method includes accessing a second series of second magnetic values that represents a second magnetic recording that includes a second set of second magnetic measurements. Each of the second magnetic values represents one of the second magnetic measurements. The method includes approximately aligning the first and second series with each other; calculating a difference between the first and second series as aligned with each other; and determining a similarity between the first and second series based on the difference.

Abstract: In one embodiment, a method includes accessing magnetic data from a magnetic-measurement device. The magnetic data corresponds to one or more locations of the magnetic-measurement device. The method includes accessing geofencing data corresponding to an area; comparing the magnetic data with the geofencing data; based on the comparison, determining that the locations correspond to the area; and, based on the determination, authenticating the magnetic-measurement device for access to one or more resources.

Abstract: In one embodiment, a method includes accessing a trajectory and comparing a first one of multiple portions of the trajectory with a second one of the portions. A greater level of confidence is associated with the first one of the portions than the second one of the portions. The method includes determining, based on the comparison, that the first and second ones of the portions approximately magnetically coincide with each other and are not approximately colocated with each other in the trajectory; comparing a first level of confidence associated with the first one of the portions with a second level of confidence associated with the second one of the portions; and, when the first level of confidence is greater than the second level of confidence, adjusting the second one of the portions to be approximately colocated with the first one of the portions in the trajectory.

Abstract: In one embodiment, a method includes accessing magnetic data from a magnetic-measurement device. The magnetic data corresponds to one or more locations of the magnetic-measurement device. The method includes accessing geofencing data corresponding to an area; comparing the magnetic data with the geofencing data; based on the comparison, determining that the locations correspond to the area; and, based on the determination, authenticating the magnetic-measurement device for access to one or more resources.

Abstract: In one embodiment, a method includes accessing a first portion of a magnetic recording. The magnetic recording corresponds to a trajectory of a device and includes a series of magnetic values that represents a set of magnetic measurements along the trajectory. The first portion corresponds to a first portion of the trajectory.

Abstract: In one embodiment, a method includes generating navigation or localization information based on a combination of first data that are based on first measurements of a magnetic field by one or more magnetic sensors and second data that are based on second measurements by one or more other sensors. The method includes determining an anomalousness of a magnetic field and, based on the determined anomalousness of the magnetic field, at least temporarily adjusting a weight of the first measurements relative to the second measurements in the generation of the navigation or localization information.

Abstract: In one embodiment, a method includes accessing a first series of first magnetic values that represents a first magnetic recording that includes a first set of first magnetic measurements. Each of the first magnetic values represents one of the first magnetic measurements. The method includes accessing a second series of second magnetic values that represents a second magnetic recording that includes a second set of second magnetic measurements. Each of the second magnetic values represents one of the second magnetic measurements. The method includes approximately aligning the first and second series with each other; calculating a difference between the first and second series as aligned with each other; and determining a similarity between the first and second series based on the difference.

Abstract: In one embodiment, a method includes collecting, by a magnetic navigation device, magnetic measurements of a particular geographical region in accordance with a position and trajectory of the magnetic navigation device; accessing a global navigation satellite system (GNSS) signal status and a network connection status on the magnetic navigation device; determining an operational mode for the magnetic navigation device based on the GNSS signal status and the network connection status; determining whether to transmit the magnetic measurements to a server or store the magnetic measurements locally on the magnetic navigation device based on the operational mode; and performing navigation or localization operations using the operational mode.

Abstract: In one embodiment, an apparatus includes a first magnetometer that measures a magnetic field. The apparatus includes a second magnetometer that measures the magnetic field. The first and second magnetometer are positioned a predetermined distance apart from each other in a direction. The apparatus includes computer-readable media embodying logic that access a first measurement of the magnetic field by the first magnetometer at a first time and a second measurement of the magnetic field by the second magnetometer at a second time. The logic compares the first measurement with the second measurement and, based at least in part on the comparison, determines that the first measurement approximately coincides with the second measurement. Based at least in part on the coincidence, the logic determines that a device comprising the apparatus has traversed the predetermined distance in the direction that they are positioned apart from each other.

Abstract: In one embodiment, a method includes receiving from one or more magnetic-measurement devices one or more trajectories comprising magnetic measurements in an area collected by the magnetic-measurement devices over a period of time. The method also includes performing one or more correlation analyses on at least some of the trajectories to determine similarities in the trajectories. The method also includes storing portions of the trajectories that have determined similarities below predetermined thresholds for incorporation into a master geomagnetic map.

Abstract: In one embodiment, a method includes at a mapping server receiving from a plurality of regional servers a plurality of regional magnetic data sets; at the mapping server updating a geomagnetic map with one or more of the regional magnetic data sets, wherein the geomagnetic map comprises one or more of the geographic regions; and from the mapping server communicating one or more portions of the geomagnetic map as updated to one or more of the regional servers for distribution as geomagnetic map information to one or more of the magnetic navigation devices for localization or navigation.