3D numerical modelling and manipulation of a shoe last
As global competition continues to increase causing market windows to shrink and product life cycles shorten, manufacturers today can no longer function without advanced design tools. These market pressures dictate that designers must embrace new, faster and better design technologies than ever before if they are to remain competitive. This is especially true in the shoe industry with the employment of up-to-date methods of design and manufacture. The development of modem CAD/CAM systems, the availability of powerful hardware at reasonable cost and vast improvements in colour graphics capabilities have made the automation of the footwear design process feasible at low cost. All of this economically justifies the creation of a system for direct shoe last design without a prototype model last. A specific onscreen methodology of a shoe last design directly from individual anthropometric data has been proposed and evaluated. A numerical methodology for onscreen visualisation with application of a new scheme of segmentation of the last surface and further manipulation of the last elements in order to create new last styles have been developed. In order to achieve this, the principles of shaping the last, the laws governing its deformation when changing the heel height and the list of possible modifications to its shape have been defined. Five global manipulation procedures have been implemented, in particular those that relate to changing the heel height. Special software has been written to visualise the results. Experimentation has proved the validity of the approach. Lasts of similar style but with different heel heights were measured and numerically modelled to compare with computer generated and modified last models. The accuracy proved to be within the limits of practical and traditional constraints.