A method for tracking moving particles in a fluid , the method comprising: illuminating the moving particles with an illumination sequence of patterns generated by a light projector ; measuring with a single camera light intensities reflected by the moving particles ; calculating , based on the measured light intensity, digital coordinates (x', y', z') of the moving particles ; calibrating , using a volume with static marks having known locations, three-dimensional positions of the static marks ; determining a mapping function f that maps the digital coordinates (x', y', z') of the moving particles to physical coordinates (x, y, z) of the moving particles using the digital coordinates (x', y', z') and results of the calibration of the three-dimensional positions of the static marks to determine plural coefficients a i of the mapping function f; and calculating the physical coordinates (x, y, z) of the moving particles based on the mapping function f, wherein the illumination sequence of patterns is generated with a single wavelength, wherein light emitted by the projector is perpendicular to light received by the single camera, and wherein the illumination sequence of patterns includes spatially varying intensity profiles or gradients, calibrating the intrinsic light intensity of each particle by generating a master light curve for the particles by illuminating static particles in a given volume, wherein the master light curve is produced from statistics of thousands of particles in the field of view of the camera, with no motion applied to the fluid ; selecting a pixel intensity I o for estimating the digital depth coordinate z' of the particles, wherein the pixel intensity I o is a combination of a central intensity and an image width; and extracting the digital depth coordinate z' of each particle from the master light curve using the pixel intensity illuminating the moving particles with an illumination sequence of patterns generated by a light projector ; measuring with a single camera light intensities reflected by the moving particles ; calculating , based on the measured light intensity, digital coordinates (x', y', z') of the moving particles ; calibrating , using a volume with static marks having known locations, three-dimensional positions of the static marks ; determining a mapping function f that maps the digital coordinates (x', y', z') of the moving particles to physical coordinates (x, y, z) of the moving particles using the digital coordinates (x', y', z') and results of the calibration of the three-dimensional positions of the static marks to determine plural coefficients a i of the mapping function f; and calculating the physical coordinates (x, y, z) of the moving particles based on the mapping function f, wherein the illumination sequence of patterns is generated with a single wavelength, wherein light emitted by the projector is perpendicular to light received by the single camera, and wherein the illumination sequence of patterns includes spatially varying intensity profiles or gradients, calibrating the intrinsic light intensity of each particle by generating a master light curve for the particles by illuminating static particles in a given volume, wherein the master light curve is produced from statistics of thousands of particles in the field of view of the camera, with no motion applied to the fluid ; selecting a pixel intensity I o for estimating the digital depth coordinate z' of the particles, wherein the pixel intensity I o is a combination of a central intensity and an image width; and extracting the digital depth coordinate z' of each particle from the master light curve using the pixel intensity <EOS>