Scanner systems
Generally, the first step in the creation of a 3D model consists in capturing the geometric and color information of the physical object. Objects can be as small as coins or as large as buildings, they can be still or move while scanning, and this has pro
- PDF / 799,672 Bytes
- 22 Pages / 439.36 x 666.15 pts Page_size
- 19 Downloads / 228 Views
Scanner systems
Generally, the first step in the creation of a 3D model consists in capturing the geometric and color information of the physical object. Objects can be as small as coins or as large as buildings, they can be still or move while scanning, and this has prompted the development of very different technologies and instruments. The aim of this chapter is to present such technologies to explain the techniques on which 3D scanners are based. Comparison in terms of accuracy, speed and applicability is reported, in order to understand advantages and disadvantages of the different approaches. How to use the information captured to compute the 3D model will be discussed in the next chapters.
2.1 3D Scanner systems A 3D scanner is composed of a set of devices and procedures able to capture the shape and the appearance of an object [30]. Generally, scanners are based on sampling the object surface. Data collected are used in the reconstruction phase to obtain the object digital model. A 3D Scanner system is, basically, a measuring instrument and therefore it can be evaluated in terms of: Accuracy The accuracy is an index that describes how close the measurements provided are to their true value. Different techniques can be used to determine such index. They can be classified in direct measurement (e.g., using a lattice of known step) and indirect (e.g., average distance of sampled points on a plane from the optimal surface). Resolution The resolution measures the details density that the system can recover, or in similar way, the minimum distance that two features should have to be discernible. Speed The speed of an acquisition system is evaluated as the time required for measuring a given feature (for example, the points per second that can be sampled). Obviously, the kind of features measured is equally important. F. Bellocchio et al., 3D Surface Reconstruction: Multi-Scale Hierarchical Approaches, DOI 10.1007/978-1-4614-5632-2 2, © Springer Science+Business Media, LLC 2013
21
22
2 Scanner systems
Flexibility The flexibility of a system is the capacity of acquiring a wide class of objects (differing in many aspects like materials and dimensions). It depends on the kind of sensors used and the size of the acquisition field. Invasiveness The invasiveness is the effect that the acquisition procedure has on the scanned object. The measurement can modify the object in different ways, typically incident light may alter the object surface or surface mechanical contact may damage a fragile object. The latter is a strong constraint for certain classes of objects like archaeological artifacts. Robustness The robustness of a system describes the sensitivity of the system to the environmental conditions. Usability The usability of a system describes the technical know-how needed to the user for a correct use of the system. Cost There are acquisition systems of very different prices. The hardware and the software used by the system determine its cost. Some of these properties can be easily quantified while others ca
Data Loading...
