Using Maya® to Create a Virtual Museum

Access to museum artifacts has greatly expanded through virtual museums. There are several approaches to creating this experience. One is to collect many images from many viewpoints of both the artwork and environment. The second is to use computer graphics (CG) to create a virtual space, in which are placed artwork, defined by their shape, color, macrostructure, and microstructure. The second approach was tested using the CG software, Maya with the mental ray plug-in. Physical measurements of the artwork’s shape, diffuse color, and macrostructure via surface normal were measured using equipment common to an imaging studio: a digital camera and strobes. Microstructure was defined within the CG software. This approach was tested on a painting in the style of Vincent van Gogh. The painting was rendered in a variety of ways: photorealistically, with a picture varnish applied, and as a colored metal. Lighting was either a typical studio set up or raking light. Details are given to produce such renderings using studio equipment and Maya for virtual gallery applications. Introduction From a college art history class to a connoisseur, groups and individuals view digital images of fine art when it is infeasible to visit a museum or gallery. Artwork can be viewed as static images, static images with interactive pan and zoom, or within a virtual museum where either many static images are combined, or through the use of computer graphics (CG) software. For static images or combined static images, there is a single camera-lighting geometry. Any texture and gloss information depends on the skill of the photographer and the specific imaging system. If such information is inadequate in the static images, reshooting is required. When CG is used to create a virtual museum experience, the camera-lighting geometry is defined during rendering. This can result in static images where the visibility of an artwork’s color, texture, and gloss is at an optimal balance. CG can also be used to create a virtual museum where the viewer is changing their position relative to the lit artwork as a way to experience artwork remotely. Rendering realistic images of two-dimensional fine art requires information about diffuse color, macrostructure defined by a surface normal or height map, and microstructure defined by a bidirectional reflection distribution function (BRDF). All three of these characteristics can be calculated or measured in different ways. Color can be captured using the Dual-RGB technique [1, 2] to estimate spectral reflectance or by using a variety of other spectral or standard imaging techniques [2]. Macrostructure, when defined by a surface normal map, a map of a surface’s relative topography, can be calculated using photometric stereo [3] or reflectance transformation imaging (RTI) [4]. Both are image based and as such, are much less expensive than instrumentation used to directly measure height. Although a height map is more accurate, visual experiments have shown that a surface normal map is an adequate substitution [5]. Microstructure, or BRDF, is measured and modeled using a variety of techniques, with a preference for image-based techniques [6]. Although it is beneficial to know the BRDF of an object, it is not necessary when using CG. The software is generally capable of approximating the way light will react when it comes in contact with the surface without knowing its specific BRDF. (The limitation is when the artwork has appreciable spatially varying microstructure.) One of the most popular commercial products for producing CG renderings is the software Maya with the mental ray plug-in, here after referred to as Maya. This publication describes how a museum-imaging studio setup coupled with Maya can produce renderings of fine art with texture and gloss information under multiple simulated lighting configurations.