In-the-ear calibration of sound pressure level may be problematic at frequencies above 2 kHz, because the pressure can vary significantly along the length of the ear canal, due to reflection of sound waves at the eardrum. This issue has been investigated by measuring behavioral thresholds to tones in a group of human subjects (N = 61) for two different insertion depths of an insert earphone. Th...

This paper analyzes the phase error for a three-dimensional (3D) shape measurement system that utilizes our recently proposed projector defocusing technique. This technique generates seemingly sinusoidal structured patterns by defocusing binary structured patterns and then uses these patterns to perform 3D shape measurement by fringe analysis. However, significant errors may still exist if an o...

Active triangulation measurement systems with a rigid geometric configuration are inappropriate for scanning large objects with low measuring tolerances. The reason is that the ratio between the depth recovery error and the lateral extension is a constant that depends on the geometric setup. As a consequence, measuring large areas with low depth recovery error requires the use of multiresolutio...

Complex anthropometrics such as area and volume, can identify changes in body size and shape that are not detectable with traditional anthropometrics of lengths, breadths, skinfolds and girths. However, taking these complex with manual techniques (tape measurement and water displacement) is often unsuitable. Three-dimensional (3D) surface imaging systems are quick and accurate alternatives to m...

Plenoptic 1.0 cameras have already been investigated as a means for performing 3DPIV. Plenoptic 2.0 cameras have an enhanced in-plane resolution, but are limited to less dense particle fields by their depth-detection method, and are thus less appropriate for 3DPIV. A technique more suited to less dense particle fields is 3DPTV. Time-resolved 3DPTV will be possible due to the high frame rate ava...

Peatland-inhabiting testate amoebae are sensitive indicators of substrate-moisture conditions and have increasingly been used in palaeohydrological studies. However, to improve accuracy of testate-amoeba-based hydrological inferences, baseline ecological data on rare taxa, a larger geographic network of calibration sites, and incorporation of long-term estimates of water-table depth are needed....

A low-cost active vision head with ten degrees of freedom is presented that has been build from off-the-shelf parts. To obtain high resolution depth information of fixated objects in the scene a general purpose calibration procedure is proposed which estimates intrinsic and extrinsic camera parameters including the vergence axes of both cameras. To produce enhanced dense depth maps a hierarchic...

Abstract. Here we revisit a recently introduced process of relative depth estimation through the matching of photometric stereo images. By considering the general solution of the differential equation which relates surface depth to the disparity map produced by the matching process, we are able to obtain a more consistent formulation of such disparity-based approach to photometric stereo. Also,...

We present three different methods for the absolute calibration of direct spectral irradiances measured with a Brewer spectroradiometer, which are shown to agree to within +/- 2%. Direct irradiance spectra derived by Brewer and Bentham spectroradiometers agree to within 4 +/- 3%. Good agreement was also found by a comparison of the aerosol optical depth and Angstrom exponent retrieved by the tw...

BACKGROUND Recently, digital photography in medicine is considered an acceptable tool in many clinical domains, e.g. wound care. Although ever higher resolutions are available, reproducibility is still poor and visual comparison of images remains difficult. This is even more the case for measurements performed on such images (colour, area, etc.). This problem is often neglected and images are f...