1. A method of forming a computer generated image that includes characteristic information of pixels, wherein the characteristic information of at least a portion of the pixels is determined at least in part by sampling data defined by a scene including a three-dimensional model of an object, the method comprising: receiving a first data set having a first statistical variance; receiving a second data set having the first statistical variance and a position relative to the first data set; using a processor, defining a third data set comprising a combination of the first and second data sets, wherein the third data set includes an overlap region corresponding with an intersection of the first and second data sets based on the position of the second data set relative to the first data set; using a processor, creating a value of the third data set in the overlap region by summing a first value of the first data set scaled by a first weight and a second value of the second data set scaled by a second weight; using a processor, determining a variance correction factor from the first and second weights; and using a processor, applying the variance correction factor to the value of the third data set, thereby modifying a statistical variance of the third data set to be substantially equal to the first statistical variance, wherein at least a portion of the third data set contributes to the characteristic information of a pixel.