Calibration and 3D reconstruction of underwater objects with non-single-view projection model by structured light stereo imaging.

Establishing the projection model of imaging systems is critical in 3D reconstruction of object shapes from multiple 2D views. When deployed underwater, these are enclosed in waterproof housings with transparent glass ports that generate nonlinear refractions of optical rays at interfaces, leading to invalidation of the commonly assumed single-viewpoint (SVP) model. In this paper, we propose a non-SVP ray tracing model for the calibration of a projector-camera system, employed for 3D reconstruction based on the structured light paradigm. The projector utilizes dot patterns, having established that the contrast loss is less severe than for traditional stripe patterns in highly turbid waters. Experimental results are presented to assess the achieved calibrating accuracy.

Measurement of fornix depth and area: a novel method of determining the severity of fornix shortening.

PURPOSE: To measure the depth and area of the fornix in normal adults and patients with symblepharon. METHODS: The fornix depth of normal eyes (n=20) and patients with symblepharon (Stevens-Johnson syndrome, n=4) was measured at six locations in each eye using non-invasive, dull-edged stainless steel metric scale. Before and after conjunctival reconstruction surgery, the depths of fornix were also measured by the same method. The overall area was assessed from those fornix depth at six points. RESULTS: The mean depths of the superior nasal and temporal, inferior nasal and temporal, fornices as well as mean depths of medial nasal and temporal canthi fornices in normal eyes were 14.1+/-2.5, 14.1+/-2.5, 10.0+/-2.1, 10.4+/-1.8, 3.0+/-0.9, and 5.2+/-1.2 mm, respectively. The mean overall area of the conjunctival fornix in normal subjects was 909.6+/-162.2 mm(2). All these parameters were significantly lower in the eyes of patients. Both depth and area after surgery were significantly deeper and larger than before. CONCLUSIONS: This estimation may prove useful when evaluating the severity of symblepharon and determining the post-surgical prognosis.

Selective removal of dissolved uranium in drinking water by nanofiltration.

A procedure for the selective removal of uranium traces dissolved in drinking water has been studied. Plate module membrane filtration equipment was operated to evaluate the performance and selectivity of three different nanofiltration flat-sheet membranes. Experiments were carried out using various commercial mineral waters with distinct physicochemical compositions. The membranes were first discriminating by their ability to reject uranium in the presence of the main cations found in mineral waters, using a 2 mg L(-1) (2000 ppb) concentration of uranium. The rejection of U(VI) was dependent on the uranyl speciation and the ionic strength. Second, removal of uranium traces (0.02 mg L(-1), 20 ppb) was performed using the nanofiltration membrane showing the highest selectivity for uranium toward alkaline and alkaline-earth ions. The results showed a high performance of the nanofiltration membrane, Osmonics DL, for selective uranium rejection at low pressure (1 bar), illustrating the advantage of nanofiltration for the selective removal of uranium from drinking water.