Angular domain reconstruction of dynamic 3D fluid surfaces

3d Digitization of Transparent and Glass Surfaces: State of the Art and Analysis of Some Methods

“…Some researchers (Morris and Kutulakos, 2011;Ding et al, 2011) employed stereo/multiple cameras to record the refractive surface, relying on a cross-view normal consistency constraint: the normals computed using the pixel-point correspondences obtained from multiple viewpoints must be consistent. Alternatively, some studies have been conducted (Ye et al, 2012;Wetzstein et al, 2011;Tsai, 2020;Tsai et al, 2021) to estimate ray-ray correspondences utilizing specific devices such as Bokode (Ye et al, 2012) and light field probes (Wetzstein et al, 2011;Tsai et al, 2021) by capturing the incident rays released from the background and the exiting rays traveling to the camera. Although 3D results appear to be highly promising, the high cost of such devices is an important downside of these approaches.…”

“…In addition, one of the main common shortcomings of the aforementioned approaches is that they provide only dependable normals but noisy depths. To provide the boundary condition for the integration of normal, they need to presume a planer surface near the boundary (Ye et al, 2012;Ding et al, 2011) or approximate the border using noisy depths (Morris and Kutulakos, 2011;Wetzstein et al, 2011). To address the restrictions mentioned above, Qian et al (2016Qian et al ( , 2017 propose a position-normal consistency based on a global optimization method to restore depth maps of the surface from front and back.…”

Free surface reconstruction of opaque liquids in microgravity, Part 1: Design and on-ground testing

“…The surface can also be used as a mirror in order to compare an original and mirrored image in what is known as pattern fringe reflectometry [20,21]. Alternatively, the distortion of a pattern behind the liquid can be employed [22,23], an approach that has been addressed with deep neural networks in modern works [24]. Particle image velocimetry makes use of the motion of seeding particles in the fluid [25,26].…”

Free surface reconstruction of opaque liquids in microgravity. Part 2: Drop tower campaign

“…Among them, displacement sensors [11,[18][19][20][21], dynamometers [22], lateral cameras [7,9,[23][24][25][26][27] or ultrasonic Doppler shift devices [19,28,29]. In the last decades, the increase in compu- * alvaro.romerocalvo@colorado.edu ORCID(s): 0000-0003-3369-8460 (Á. Romero-Calvo) tational power has motivated the application of optical methods, such as stereo imaging [30], digital image correlation [31][32][33][34][35], pattern fringe reflectometry [36,37], or particle image velocimetry [38,39]. Alternative approaches employ the movement of a float [40], or the distortion of a laser on the surface [41] to obtain liquid level measurements.…”