Fluorescence based tracking of a light-emitting marker in a bodily fluid stream is conducted by: providing a light-emitting marker into a fluid stream； establishing field of view monitoring by placement of a sensor, such as a high speed camera, at a region of interest； recording image data of light emitted by the marker at the region of interest； determining time characteristics of the light output of the marker traversing the field of view； and calculating flow characteristics based on the time characteristics. Furthermore generating a velocity vector map may be conducted using a cross correlation technique, leading and falling edge considerations, subtraction, and/or thresholding.
