A major drawback in the use of wood materials for construction and decorative applications is its sensitivity to light. Numerous researchers have shown that the ultraviolet (UV) as well as fractions of the visible (VIS) spectrum of solar radiation cause most of the chemical modification and mechanical breakdown of exposed wood. To insure the long life of wood substrates, they are usually coated with various decorative and protective finishes. The protection effect depends strongly on the opacity, i.e., the degree of pigmentation of the coatings. However, the use of UV absorbers (UVA) and hindered amine light stabilizers (HALS) both in the coating system and also in a direct wood impregnation step can improve the light stability considerably. Here the knowledge of the light sensitivity of wood is crucial for an optimal photoprotection concept for coatings and the wood substrate. This paper highlights findings of a systematic investigation of the light sensitivity of pine wood (Pinus radiata). Furthermore, it describes the correlation between quantity and type of organic UVA and HALS as well as the lignin stabilizer concept and the degree of pigmentation of the coating. These findings are of great importance for an efficient and economic use of light stabilizers in film-forming wood coating systems for pale wood species and allow a cost-effective stabilization.

We present a new checkerboard detection algorithm which is able to detect checkerboards at extreme poses, or checkerboards which are highly distorted due to lens distortion even on low-resolution images. On the detected pattern we apply a surface fitting based subpixel refinement specifically tailored for checkerboard X-junctions. Finally, we investigate how the accuracy of a checkerboard detector affects the overall calibration result in multi-camera setups. The proposed method is evaluated on real images captured with different camera models to show its wide applicability. Quantitative comparisons to OpenCV's checkerboard detector show that the proposed method detects up to 80% more checkerboards and detects corner points more accurately, even under strong perspective distortion as often present in wide baseline stereo setups.

The proposed solution is able to solve surface registration problems with an accuracy suitable for radiotherapy cases where external surfaces offer primary or complementary information to patient positioning. The system shows promising dynamic properties for its use in gating/tracking applications. The overall system is competitive with commonly-used surface registration technologies. Its main benefit is the usage of a cost-effective off-the-shelf technology for surface acquisition. Further strategies to improve the registration accuracy are under development.

In this technical note we present a system that uses time-of-flight (ToF) technology to acquire a real-time multidimensional respiratory signal from a 3D surface reconstruction of the patient's chest and abdomen without the use of markers. Using ToF sensors it is feasible to acquire a 3D model in real time with a single sensor. An advantage of ToF sensors is that their high lateral resolution makes it possible to define multiple regions of interest to compute an anatomy-adaptive multidimensional respiratory signal. We evaluated the new approach by comparing a ToF based respiratory signal with the signal acquired by a commercially available external respiratory gating system and achieved an average correlation coefficient of 0.88.

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