The determination of the amount of compensation shall reflect the value of the property immediately prior to the filing of the petition under G.S. 40A-20 or the complaint under G.S. 40A-41 and except as provided in the following sections shall not reflect an increase or decrease due to the condemnation. The day of the filing of a petition or complaint shall be the date of valuation of the interest taken. (1981, c. 919, s. 1.)