Reflectance Transformation Imaging (RTI)
Technical specifications
Reflectance Transformation Imaging is used to document tiny features, such as, incisions in paintings and historical prints techniques. RTI is a computational photographic technique and it is used in a number of fields related to art examination and documentation because it provides a virtual and enhanced visualization of an object’s surface.
Reflectance Transformation Imaging (RTI) is an advanced imaging technique used in cultural heritage preservation to capture the surface details of objects with remarkable precision. RTI involves taking multiple photographs of an object under different lighting angles and combining them using specialized software. This process creates an interactive, relightable image that reveals intricate surface textures and features, such as tool marks, inscriptions, and surface wear, that may be difficult to see with the naked eye. Applications of RTI in cultural heritage include:
Artifact Analysis: RTI allows researchers to examine fine details on artifacts such as coins, pottery, sculptures, and jewelry, aiding in identification and authentication.
Epigraphy: Inscriptions on stone, metal, or other materials can be brought to life, making it easier to read faded or eroded text.
Art Conservation: RTI can help conservators assess the condition of artworks, including paintings and sculptures, by highlighting surface irregularities, cracks, and restoration work.
Documenting Historical Sites: RTI is useful for recording and preserving the surface details of historical sites, such as carvings, engravings, and architectural elements.
Interactive Exhibits: Museums can use RTI to create interactive exhibits that allow visitors to explore cultural heritage objects in detail, enhancing their educational and engaging experience.
Overall, RTI is a valuable tool in the field of cultural heritage for studying, documenting, and preserving historical objects and sites with a high degree of accuracy and detail.
RTI black sphere and where to find them
RTI is a pretty simple technique and you can practice it with your basic photographic equipment. The only extra tool you need is a black reflective sphere. This video show you some ideas on how to make your own RTI spheres.
In Reflectance Transformation Imaging (RTI), finding the right sphere is crucial for capturing accurate and high-quality images. The sphere serves as a reference point for the lighting in each photograph taken of the object. Here’s why finding the right sphere is important:
Reflective Properties: The sphere used in RTI should have a highly reflective surface. This allows it to clearly capture the position and intensity of the light source in each image.
Accurate Light Tracking: By examining the reflections on the sphere’s surface, the RTI software can precisely determine the angle and direction of the light source for each photograph. This information is essential for reconstructing the surface of the object accurately.
Consistent Calibration: A consistent, properly placed sphere ensures that the RTI setup remains calibrated across all images. This consistency is key to creating an interactive, high-quality image that allows for detailed examination of the object’s surface.
Software Compatibility: Using the right sphere makes it easier for RTI software to process the images. The software relies on the sphere’s reflections to align and combine the photographs, generating an interactive image with adjustable lighting.
Enhances Image Quality: A good sphere choice contributes to the overall quality of the RTI process. It helps produce images that are more precise, providing clearer insights into the object’s surface textures and features.
In summary, selecting the right sphere for RTI is essential for obtaining precise and reliable data that can be used to create high-quality, interactive images for studying and preserving cultural heritage objects.
Applications
| Publications on Reflectance Transformation Imaging |
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| A. Cosentino, S. Stout, C. Scandurra “Innovative Imaging Techniques for Examination and Documentation of mural paintings and historical graffiti in the catacombs of San Giovanni, Syracuse” International Journal of Conservation Science, 6, 1, 23-34, 2015. |
| A. Cosentino “Macro Photography for Reflectance Transformation Imaging: A Practical Guide to the Highlights Method” e-conservation Journal 1, pp. 70-85, 2013. |
