A method of forming a three-dimensional object comprising: irradiating (501, 601) a build material bed with an array of lamps, the array of lamps comprising a plurality of lamps; detecting (502, 602), with a thermographic camera, a temperature of a control point within at least one zone of the build material bed; and adjusting (503, 605) a power level supplied to at least one of the lamps of the array of lamps if the detected temperature of the control point of the at least one zone of the build material bed is not equal to a set temperature characterized in that adjusting the power level supplied to the at least one of the lamps of the array of lamps comprises: defining a number of weights assigned to each of the plurality of lamps based on the position of the lamps within the lamp array, wherein: lamps located on corners of the array of lamps are assigned a weight of 1; lamps located on sides of the array of lamps are assigned a weight less than 1; and lamps located on an interior portion of the array of lamps are assigned a weight less than lamps located on the sides of the array of lamps; and adjusting the power level supplied to the at least one of the lamps of the array of lamps based on the weighted levels defined for each of the plurality of lamps. irradiating (501, 601) a build material bed with an array of lamps, the array of lamps comprising a plurality of lamps; detecting (502, 602), with a thermographic camera, a temperature of a control point within at least one zone of the build material bed; and adjusting (503, 605) a power level supplied to at least one of the lamps of the array of lamps if the detected temperature of the control point of the at least one zone of the build material bed is not equal to a set temperature characterized in that adjusting the power level supplied to the at least one of the lamps of the array of lamps comprises: defining a number of weights assigned to each of the plurality of lamps based on the position of the lamps within the lamp array, wherein: lamps located on corners of the array of lamps are assigned a weight of 1; lamps located on sides of the array of lamps are assigned a weight less than 1; and lamps located on an interior portion of the array of lamps are assigned a weight less than lamps located on the sides of the array of lamps; and adjusting the power level supplied to the at least one of the lamps of the array of lamps based on the weighted levels defined for each of the plurality of lamps. defining a number of weights assigned to each of the plurality of lamps based on the position of the lamps within the lamp array, wherein: lamps located on corners of the array of lamps are assigned a weight of 1; lamps located on sides of the array of lamps are assigned a weight less than 1; and lamps located on an interior portion of the array of lamps are assigned a weight less than lamps located on the sides of the array of lamps; and lamps located on corners of the array of lamps are assigned a weight of 1; lamps located on sides of the array of lamps are assigned a weight less than 1; and lamps located on an interior portion of the array of lamps are assigned a weight less than lamps located on the sides of the array of lamps; and adjusting the power level supplied to the at least one of the lamps of the array of lamps based on the weighted levels defined for each of the plurality of lamps.