Synthetic aperture imaging for fluid flows

A synthetic aperture three dimensional fluid flow imaging apparatus, comprising:

• a plurality of image recording devices, at least two of said plurality of image recording devices oriented so as to view a volume to be imaged along mutually non-parallel directions;
• and
• a data processing apparatus based on a general purpose programmable computer configured to operate under control of a set of instructions recorded on a machine readable medium, said data processing apparatus when operating under control of said set of instructions configured to perform the steps of:
• capturing a plurality of images using said at least two image recording devices oriented along mutually non-parallel directions to generate three dimensional intensity fields;
• subtracting a sliding minimum value having a window size from the images;
• convolving each image with a 3×3 Gaussian kernel;
• equalizing a histogram of each image to a histogram of said image with the highest contrast;
• increasing said contrast of each image by trimming a bottom range and a top range of intensity values;
• subtracting a sliding minimum value having a window size from the images after the step of increasing said contrast to give a plurality of preprocessed images;
• refocusing said plurality of preprocessed images on at least one refocus plane in the field of view of each image recording device to generate reconstructed three dimensional intensity fields on a plane placed at a location within said volume to be imaged;
• performing intensity field cross-correlation on said reconstructed three dimensional intensity fields to extract therefrom velocity fields within said volume to be imaged, said velocity fields representing velocities of objects within said volume to be imaged;
• and
• recording said velocity fields for later use.