At the request of the assessor, the board of supervisors shall authorize and direct the assessor to prepare, or to supervise the preparation of, maps and block-books as may be needed for the assessor’s office to meet the requirements of the state board with respect thereto. All costs incurred in connection therewith shall be a charge against the county general fund, payable in the same manner as other county charges. This procedure shall be in addition to any other procedure relating to matters as may otherwise be provided by law.