A system comprising: circuitry configured to: provide candidate installation states for each of a plurality of imaging devices from a relationship between current installation states of each of the plurality of imaging devices, each of the candidate installation states and current installation states being at least one of an installation position and an installation posture, the installation posture indicating a direction of an optical axis of an imaging surface of each of the plurality of imaging devices and a rotation angle of each of the plurality of imaging devices relative to the optical axis; output a provided candidate installation state for at least one of the plurality of imaging devices from the current installation state of each of the plurality of imaging devices and the provided candidate installation states; one of: (a) acquire sensor information generated by position detection units of the plurality of imaging devices and output from each of the plurality of imaging devices and determine the information indicating a current installation state of each of the plurality of imaging devices based on the acquired sensor information; (b) acquire image data captured by each of the plurality of imaging devices and calculate the information indicating the current installation state from the acquired image data; and (c) determine the candidate installation states from an imaging mode for each of the plurality of imaging devices; and output display information including a first image for the output candidate installation state superimposed with a second image for the current installation state of the at least one of the plurality of imaging devices; wherein the system is configured to acquire the information indicating a current installation state from each of the plurality of imaging devices via a communication link with each of the plurality of imaging devices. circuitry configured to: provide candidate installation states for each of a plurality of imaging devices from a relationship between current installation states of each of the plurality of imaging devices, each of the candidate installation states and current installation states being at least one of an installation position and an installation posture, the installation posture indicating a direction of an optical axis of an imaging surface of each of the plurality of imaging devices and a rotation angle of each of the plurality of imaging devices relative to the optical axis; output a provided candidate installation state for at least one of the plurality of imaging devices from the current installation state of each of the plurality of imaging devices and the provided candidate installation states; one of: (a) acquire sensor information generated by position detection units of the plurality of imaging devices and output from each of the plurality of imaging devices and determine the information indicating a current installation state of each of the plurality of imaging devices based on the acquired sensor information; (b) acquire image data captured by each of the plurality of imaging devices and calculate the information indicating the current installation state from the acquired image data; and (c) determine the candidate installation states from an imaging mode for each of the plurality of imaging devices; and (a) acquire sensor information generated by position detection units of the plurality of imaging devices and output from each of the plurality of imaging devices and determine the information indicating a current installation state of each of the plurality of imaging devices based on the acquired sensor information; (b) acquire image data captured by each of the plurality of imaging devices and calculate the information indicating the current installation state from the acquired image data; and (c) determine the candidate installation states from an imaging mode for each of the plurality of imaging devices; and output display information including a first image for the output candidate installation state superimposed with a second image for the current installation state of the at least one of the plurality of imaging devices; wherein the system is configured to acquire the information indicating a current installation state from each of the plurality of imaging devices via a communication link with each of the plurality of imaging devices.