Gloss, Color, and Topography Scanning for Reproducing a Painting’s Appearance Using 3D Printing

Abstract

High fidelity reproductions of paintings provide new opportunities to museums in preserving and providing access to cultural heritage. This paper presents an integrated system which is able to capture and fabricate color, topography and gloss of a painting, of which gloss capturing forms the most important contribution. A 3D imaging system, utilizing stereo imaging combined with fringe projection, is extended to capture spatially-varying gloss, based on the effect of specular reflectance polarization. The gloss is measured by sampling the specular reflection around Brewster's angle, where these reflections are effectively polarized, and can be separated from the unpolarized, diffuse reflectance. Off-center gloss measurements are calibrated relative to the center measurement. Off-specular gloss measurements, following from local variation of the surface normal, are masked based on the height map and corrected. Shadowed regions, caused by the 3D relief, are treated similarly. The area of a single capture is approximately 180 mm × 90 mm at a resolution of 25 µm × 25 µm. Aligned color, height, and gloss tiles are stitched together off-line, registering overlapping color regions. The resulting color, height and gloss maps are inputs for the poly-jet 3D printer. Two paintings were reproduced to verify the effectiveness and efficiency of the proposed system. One painting was scanned four times, consecutively rotated by 90°, to evaluate the influence of the scanning system geometric configuration on the gloss measurement. Experimental results show that the method is sufficiently fast for practical application, i.e. to scan a whole painting within eight hours, during closing hours of a museum. The results can well be used for the purpose of physical reproduction and other applications needing first-order estimates of the appearance (e.g. conservation diagnostics and condition reports). Our method to extend appearance scanning with gloss measurements is a valuable addition in the quest for realistic reproductions, in terms of its practical applicability -number of images needed for reconstruction and speed -and its perceptual added value, when added to color and topography reproduction.Developments in 3D scanning and 3D printing systems provide new opportunities to create high-fidelity physical reproductions of paintings. Facsimiles (one-to-one reproductions simulating the artifact's appearance), are already made of artifacts like manuscripts, for instance to support storytelling in exhibitions, when the original is too fragile to show. Up to recently, copies with such likeness did not exist for paintings [13]. Facsimiles of paintings, in addition to the original artwork, can play a role in museums' missions of preserving as well as providing access to cultural heritage. Possible applications of scanning and reproduction include: Multi-modal documentation of an artwork (e.g. adding to high-resolution photography, infrared, and X-ray imaging, as shown in the Bosch Research and Conservation Project [30,43]), showing an artwo...

Comparison of three 3D scanning techniques for paintings, as applied to Vermeer’s ‘Girl with a Pearl Earring’

“…Structured light 3D scanning, using a projector combined with either one or two cameras has also been proposed to measure the topography of painted surfaces (e.g. [16][17][18][19][20][21]). The latter approaches [19][20][21] use a de-focused projection pattern, whereby the sampling resolution only depends on the camera resolution, rather than the (lower) projector resolution.…”

“…The Std-Res 3D Scan (described in [20], based on the original design by [19]), sampled at a lateral resolution (XY) of 25 µm , and is shown in Fig. 3b, c. The scan was carried out overnight, and under constant temperature and RH conditions, in complete darkness to minimise the influence of environmental conditions on the scan results.…”

“…Missing values were interpolated based on surrounding pixels. A detailed description of the image processing can be found in [19,20]. The output of these systems is an aligned colour and height map.…”

“…Furthermore, we encountered issues with stitching the High-Res 3D data set, as our current approach to stitching (as is used in for instance [20]), is limited by its memory requirements for such large data sets. Also the Hirox e-tiling software did not allow stitching the larger ROI at full resolution.…”

“…The lack of this information can be overcome by mapping the topographical (and stratigraphy) data to a colour image, allowing enhanced data interpretation and ease of localisation on the artwork. Furthermore, the Std-Res 3D scan system is capable of measuring additional modalities of a painting's appearance, namely measuring the spatially-varying gloss of the surface [20]. This has the potential to offer an even richer documentation of the appearance and a painting's state.…”