Spectral and 3d Cultural Heritage Documentation Using a Modified Camera

Abstract

ABSTRACT:Spectral and 3D imaging techniques are used for museum imaging and cultural heritage documentation providing complementary information to aid in documenting the condition, informing the care, and increasing our understanding of objects. Specialised devices for spectral and 3D imaging may not be accessible for many heritage institutions, due to cost and complexity, and the modification of a consumer digital camera presents the potential of an accessible scientific tool for 2D and 3D spectral imaging. Consumer digital cameras are optimised for visible light, colour photography, but the underlying sensor is inherently sensitive to near ultraviolet, visible, and near infrared radiation. This research presents the characterisation of a modified camera to investigate the impact of the modification on the spectroradiometric and geometric image quality with the intention of the device being used as a scientific tool for cultural heritage documentation. The characterisation includes the assessment of 2D image quality looking at visual noise, sharpness, and sampling efficiency using the target and software associated with the Federal Agencies Digitization Guidelines Initiative. Results suggest that these modifications give rise to discrepancies in computed surface geometries of the order of ± 0.1 mm for small to medium sized objects used in the study and recorded in the round (maximum dimension 20 cm). Measuring the spectral response quantifies the modified camera as a scientific device for more accurate measurements and provides indications of wavelengths that could improve documentation based on sensitivity. The modification of a consumer digital camera provides a less expensive, high-resolution option for 2D and 3D spectral imaging.

First Assessments on Heritage Science Oriented Image-Based Modeling Using Low-Cost Modified and Mobile Cameras

“…Although, recently, simple to use automated or semi-automated photogrammetric software implementing Structure from Motion (SfM) and Multiview Stereo (MVS) algorithms, which are becoming extremely popular for heritage applications, in combination with low-cost sensors, have made heritage digitization more feasible (Georgopoulos and Stathopoulou, 2017). More specifically, the availability of low-cost digital and modified digital cameras for UVA, IRA and multi-spectral imaging, that are not any more restricted to very low resolutions has made possible the direct modeling from non-VIS imagery (Grifoni et al, 2018;Webb et al, 2018). It should also be mentioned that many contemporary mobile phone cameras can produce imagery of adequate quality for photogrammetric use and have already successfully been implemented in case studies for rapid cultural heritage mapping (Calantropio et al, 2017).…”

Image-based metric heritage modeling in the near-infrared spectrum

“…The availability of high-resolution, easily operated digital cameras for NIR acquisition, in combination with SfM/MVS image-based modeling techniques, has made feasible the 3D spectral modeling for heritage applications. Contemporary research, which showed promising results [22][23][24][25][26][27][28], led us to the motivation for further experimentation.…”

Image-based metric heritage modeling in the near-infrared spectrum

“…The availability of high-resolution easily operated digital cameras for NIR acquisition, in combination with SfM/MVS image-based modeling techniques, has made feasible the 3D spectral modeling for heritage applications. Contemporary research which showed promising results [29][30][31][32] led us to the motivation for further experimentation.…”