A method and system of surface analysis or product design comprising using a plurality of input scans, commonly orienting the scans, establishing a common origin, creating a ray mesh having a plurality of rays extending from the origin, calculating intersections of the rays with the input scans, analyzing the intersection along each ray, generating percentile envelopes by connecting similar percentile points on each ray, and designing products using percentile envelopes as a guide. The system may comprise a device for scanning surfaces, a fit plan setting forth predetermined guidelines for the product, a coordinate transformation algorithm, an envelope processor comprising an intersection calculation algorithm for analyzing data sets and generating output surfaces, and an output file.