Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.

Abstract: Positioning data generated by the positioning module of a portable device is received. The positioning data was generated using signals received at the portable receiver from respective signal sources (such as satellites). Positioning data generated by one or more non-surveyed devices is also received. The positioning data from the one or more non-surveyed devices has a high degree of reliability as compared with the position data from the portable device. The highly reliable positioning data from the one or more non-surveyed devices is further processed to develop positioning corrections for the portable device.

Abstract: A position fix identifying a geographic location of a receiver is received. The position fix was generated using signals received at the receiver from respective high-altitude signal sources (such as satellites). Imagery of a geographic area that includes the geographic location is also received. The imagery is automatically processed to determine whether one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated. In response to determining that one or more of the high-altitude signal sources were occluded from the geographic location when the position fix was generated, the position fix is identified as being potentially erroneous.