Photometric stereo-imaging is a 3D imaging method that allows reconstruction of the surface normals of the imaged object when illumination is made from different angles.
The data here is from an implementation of photometric stereo-imaging, where the four light sources that illuminate the object from different angles are modulated with a sinusoidal signal at 3.05 Hz, 6.10 Hz, 9.16 Hz, and 12.21 Hz. File "sine_waveform.txt" contains the optical intensity seen by one representive camera pixel (running at 60 fps), where the first column is the time in seconds and the second column is the pixel value at that time. File "sine_PFT.txt" contains the power Fourier transform of this waveform, where the first column is the frequency in Hz and the second column is the corresponding Fourier coefficient.
From these, the intensity contribution from each of the four LEDs at this camera can be calculated. These intensity contributions for each of the 640x480 pixels are given in files "LED1_sine.txt", "LED2_sine.txt", "LED3_sine.txt", and "LED4_sine.txt". The corresponding normalised surface normal vector components in x-, y- and z-direction are given in files "nx_sine.txt", "ny_sine.txt", and "nz_sine.txt".
We have also shown that the same LEDs can be used for data transmission to a receiver within the imaged scene while performing photometric stereo-imaging at the same time. The surface normal components from this experiment are given in files "nx_data.txt", "ny_data.txt", and "nz_data.txt". While the scene was imaged, data were transmitted wirelessly using an on-off-keying format on top of the LED modulation for the imaging. The optical signal that was received by a photodiode in the scene while transmitting at 0.9 Mb/s is given in file "data_waveform.txt", where the first column is the time in seconds and the second column is the photoreceiver signal in Volts. The bit error rate has been measured for various data rates and is given in file "data_BER.txt", where the first column is the data rate in Mb/s and the second column is the bit error rate.