Most of the automation for 3D acquisition concerns objects with simple shape, like mechanical parts. For cultural heritage artefacts, the process is more complex, and it doesn't exist general solution nowadays. This paper presents a method to generate a complete 3D model of cultural heritage artefacts. In a first step, MVC is used to solve the view planning problem. Then, holes remaining in 3D model are detected, and their features are calculated to finish acquisition. Different post-processing are applied on each view to increase quality of the 3D model. This procedure has been tested with simulated scanner, before being implemented on a motion system with five degrees of freedom. Key Words: 3D acquisition, cultural heritage artefacts, scanners automation, view planning The demand for high-quality three dimensional (3D) models of complex objects is growing in a wide range of applications (e.g., industrial [1], medical [2-3-4-5-6], cultural [7-8-9], architectural [10-11], ...). Numerous applications require the computer vision approach to object surface reconstruction. These applications relate to fragile objects whose handling is impossible. Only non-contact sensors are usable. 3D acquisition devices collect 3D coordinates of an object surface [12] [13] . To acquire the shape from all sides, many scans are necessary. Our system is based on several assumptions: the scanner remains calibrated between each acquisition and the object size and material is compatible with the scanner specifications. For each scan, post-processing is required (noise removing, segmentation, registering, meshing, smoothing and mesh cleaning). Each scan captures a portion of the shape of the object, and in order to merge all of the scans into a single shape we must place them in the same coordinate system. If there is a lack of data, others scans may be necessary. 3D acquisition and post-processing are long and the experience of the user has a significant influence on the resulting 3D model quality. Acquisition and post-processing need to be automated in order to reduce human operator influence and speed up the measurement process. The NBV algorithms have for objective to calculate this set of positions necessary for the digitization. These algorithms can be divided in two categories : model based methods (when CAD model or coarse model is available) and non model based methods (when no a priori knowledge of the shape of the object is available). For cultural heritage artefacts, we must use non-model based methods. The main objective of the proposed method is to automatically reach maximum surface coverage.
Loriot REF implemented a system with a similar setup using a fixed scanner and moving the object for the NBV.
Non-Model Based Method for an Automation of 3D Acquisition and Post-Processing
ELECTRONIC LETTERS ON COMPUTER VISION AND IMAGE ANALYSIS 7(3): 67-82
Computer Science