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Abstract Recent studies have demonstrated that Reflection Transformation Imaging (RTI) is an effective tool for both robust documentation and interpretive study of cultural heritage materials. Widespread adoption of this technique had been limited by the requirement for prior knowledge of the light positions used to sample the reflectance field and associated complex and expensive imaging structures. We will demonstrate a set of new, simple, low-cost reflection information capture techniques. These methods permit recovery of lashing direction for each photographic sample after the reflectance information capture session. This eliminates the need for costly mechanical structures or templates, greatly reduces cost, simplifies field work in irregular terrain or obstructed environments, and is well suited for documentation under laboratory conditions. The method has been used with subjects as small as 4 square cm and as large as 6 square meters. We will show examples of the technique applied to rock art, large Assyrian basrelief sculpture, Byzantine mosaics, Sumerian epigraphy, and oil paintings. In its simplest form, reflection information can be captured with only a digital camera, flash, a shiny black ball, and a piece of string. Taking a handful of handheld images of the same subject enables photogrammetric elimination of optical distortions and ortho-rectification of the reflectance samples. Adding a second black ball increases the accuracy of recovered 3D information. Adding a second camera for stereoscopic imaging further enhances the 3D record. Repeating the process from additional camera orientations can acquire documentation "in the round". These techniques, specifically designed for cultural heritage professionals, are easy to learn. They may be used without the presence of a computer imaging technologist. The acquired data contains robust information about the object's 3D shape and surface properties. This information can be used to build dynamic, interactive, Reflection Transformation Images (RTI) capable of mathematical enhancement and rendered in a variety ways to disclose important characteristics. The captured 3D surface information permits automatic generation of drawings, free from optical distortions. For areas of study where drawings remain the vehicle of discourse, these algorithmically produced drawings can be edited by hand or used 'as is' and are compatible with existing documentary and interpretive work practice.
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