Application, rendering and display of automotive paint.

Abstract

New computer graphics tools are developed for use in the automotive paint design and paint application industries. These tools are designed to aid in every aspect of automotive painting from initial paint design all the way to viewing a final spray paint job. This thesis also provides new computer graphics techniques by leveraging industrial appearance standards and measurement instruments to yield new interaction, rendering and display algorithms. First, a system is introduced for the simulation of spray painting. Head mounted display goggles are combined with a tracking system to allow users to paint a virtual surface with a spray gun. Ray tracing is used to simulate droplets landing on the surface of the object, allowing arbitrary shapes and spray gun patterns to be used. This system is combined with previous research on spray gun characteristics to provide a realistic simulation of the spray paint including the effects of viscosity, air pressure, and paint pressure. Experiments were performed to validate the system for use as a training tool. Next, a virtual airbrush tool is introduced. The basic particle simulation used in the spray paint system is modified to include the finer control needed for airbrushing. Paint mixing between colors applied to the surface is modeled using Kubelka-Munk theory. Computerized stencils, including semi-permeable stencils, can be manually positioned by the artist or projected onto the object’s surface. The resulting airbrush system can be used by airbrush artists to both practice their craft as well as to decorate virtual models. The dissertation then utilizes an industrial measurement instrument to simulate the surface roughness in automotive paint finishes. This simulation is integrated with a design interface to enable industry professionals to devise new paints that have detailed surface effects. The industrial measurement device can also be used to rapidly measure and render real world materials without the need for elaborate full BRDF acquisition tools. Finally, the surface model developed in this research can be used to study human detection of small scale surface roughness. Lastly, new projection systems are introduced to display the paints generated by the previous algorithms. A desired paint is projected onto the surface of an object, making that object appear to be painted with that material. This allows painters to evaluate how the final painted surface will look in a very natural way. A novel projection system is also described in which the user can hold and evaluate a flexible sample of virtual paint. This provides a more compelling display of the paint than a standard 2D monitor can generate. These display methods can also be used to display materials other than paint, potentially benefiting a large range of industries. The combination of these tools is intended to allow spray painters to design paints, paint them onto an automobile or other object, and verify exactly what the result will look like before ever having to manufacture the paint itself. The use of these tools could therefore reduce wasted paint, speed up training times, and allow for precise design of automobile appearance: all before ever manufacturing any real paint. In addition to aiding paint industries, these tools enhance the current state of the art in computer graphics. The airbrush tool provides a new texture creation system that existing airbrush artists can use with little to no training; the surface roughness simulation provides enhanced rendering of automotive paint that could be used in movies and games; and the projection display system improves the state of the art in augmented reality systems.