People of the Jaguar

3-D Imaging of Mayan Vases

The rollout images of the Mayan vases in the exhibition People of the Jaguar were produced using a new three-dimensional (3-D) colour digital imaging technique developed at the National Research Council of Canada (NRC), in collaboration with the Canadian Conservation Institute (CCI).

The system utilizes a unique synchronized laser scanner camera system which simultaneously projects red, green and blue (RGB) laser beams to form a small "white" laser spot on the object. The light reflected back into the camera from the object is separated by a prism into its RGB components and focused on a position and brightness sensitive detector. As the vase is rotated on a turntable in front of the camera (Figure 1), the scanner records a number of line profiles which together form a rollout image of the design. The unique feature of this imaging technique is that, because spatial coordinates are made available, images can be rolled back in 3-D space to recreate realistic views of the object, from any viewpoint, using computer graphics.

Figure 1. The laser scanner imaging system is illustrated here digitizing a Mayan vase from the Canadian Museum of Civilization. The vase is rotated through 360 degrees on a turntable while the camera scans a white laser spot on the surface. As the vase is rotated, 2048 line profiles (white line) are obtained to produce an unrolled, high resolution 3-D colour image.

Objects ranging in size from as small as pin-mounted insects to paintings can be accommodated with the system. An important aspect of the system is that the physical dimension and colour value measurements are repeatable. This facilitates the accurate monitoring of changes to the colour and shape of important objects by comparing scanned images at different periods in time.

This technology offers several new applications and "electronic highway" opportunities to museum and galleries. These include:

• The provision of accurate high resolution "gold standard" or archival quality digital records of the shape, colour and dimensions of important objects. These data files can be used for a wide variety of activities including research, scholarship, display, conservation, publication, reproduction, insurance and repatriation applications.

• The display of high resolution digital 3-D images of objects rendered in real time with excellent colour reproduction. Using stereo viewing equipment, the objects can be examined in stereo with a realistic perception depth.

• The examination and display of unique features of objects which cannot be displayed by other techniques. Examples include the rollout images of the Mayan vases, the brush stroke on paintings, enlargements of miniature objects or toolmarks on artifacts.

• The incorporation of images into electronic museum or gallery database systems for virtual museum, information kiosk, CD-ROM or related interactive multimedia applications.

• The fabrication of replicas using modern rapid prototyping technologies.

• The compact file size facilitates convenient data storage as well as transmission to remote electronic museum sites using standard communication links including satellite.

Prepared by Réjean Baribeau and John Taylor, CCI.

- more -