Mitsuba0.6 Doppler Time-of-Flight Renderer

Project Page | Paper | Code(Mitsuba3)

About

This repository is the official Mitsuba0.6 implementation of "Doppler Time-of-Flight Rendering" by Juhyeon Kim, Wojciech Jarosz, Ioannis Gkioulekas, Adithya Pediredla (SIGGRAPH Asia 2023, journal paper). Please also check Mitsuba3 implementation at here.

Install

To compile, follow the original Mitsuba0.5's compliation guide at here.

Instead of default float precision, please use double precision (config_double.py).

Parameter Explanation

New integrator named dopplertofpath is added for Doppler ToF rendering. Followings are explanation for each parameter.

ToF Related

• time : Exposure time in sec. (default : 0.0015)

• w_g : Illumination modulation frequency in MHz. (default : 30)

• g_1 : Illumination modulation scale. (default : 0.5)

• g_0 : Illumination modulation offset. (default : 0.5)

• w_s : Sensor frequency in MHz. (default : 30)

• sensor_phase_offset : Sensor phase offset in radian. (default : 0)

• We also provide some syntactic sugar parameters with normalization.

  • hetero_frequency : Relative heterodyne frequency. 0 for perfect homodyne and 1 for perfect heterodyne. This is a syntactic sugar for w_s. If this value is set, w_s is calculated from this value. (default : not used)
  • hetero_offset : Relative heterodyne offset. 0 for 0 radian and 1 for 2pi radian. This is a syntactic sugar for sensor_phase_offset. If this value is set, sensor_phase_offset is calculated from this value. (default : not used)

• wave_function_type : Modulation waveform. Refer following table for exact configuration. (default : sinusoidal)

wave_function_type	Sensor Modulation	Light Modulation	Low Pass Filtered
sinusoidal	sinusoidal	sinusoidal	sinusoidal
rectangular	rectangular	rectangular	triangular
triangular	triangular	triangular	Corr(tri, tri)
trapezoidal	trapezoidal	delta	trapezoidal

• low_frequency_component_only : Whether to use low pass filtering for modulation functions. (default : true)

Sampling Related

• time_sampling_mode : Times sampling method.

  • uniform : uniform sampling
  • stratified : stratified sampling
  • antithetic : shifted antithetic sampling
  • antithetic_mirror : mirrored antithetic sampling
  • analytic : analytic integration (biased)

• antithetic_shifts : User defined antithetic shifts. Multiple input is available separated by underbar. (e.g 0.5 for single antithetic sample or 0.12_0.35 two antithetic samples) (default : 0.5 for antithetic, 0.0 for antithetic_mirror)

• antithetic_shifts_number : Number of antithetic shifts with equal interval. If this value is set, this is used instead of antithetic_shifts. This is also used for number of stratum for stratified. (default : 0)

• use_full_time_stratification : Whether to use full stratification over time. If set to true, it works differently by time_sampling_mode. (default : false)

  • stratified : correlated randomly over different stratum (Fig.8-(b) in the main paper)
  • antithetic : use stratification for primal sample (Fig.8-(e) in the main paper)
  • antithetic_mirror : use stratification for primal sample (Fig.8-(d) in the main paper)

• spatial_correlation_mode : Spatial correlation methods. Note that methods start with ray explicitly correlate two paths in ray-by-ray style.

  • none : no correlation
  • pixel : repeat camera ray (use same pixel coordinate) between multiple rays
  • sampler : repeat sampler between multiple rays (temporal random replay, implicit)
  • ray_position : correlate intersection point between two rays (temporal random replay)
  • ray_sampler : repeat sampler between two rays (temporal path reconnection)
  • ray_adaptive : select one of ray_position, ray_sampler based on material property

• force_constant_attenuation : Whether to force constant attenuation as [Heide, 2015] did. true is using zero-order Taylor approximation while false is using first-order Taylor approximation. Only used for analytic. (default : false)

• primal_antithetic_mis_power : MIS power for primal and antithetic sample. Only used for other than analytic. Refer Sec 4.1 in supplementary material for details. (default : 1.0)

Others

• image_offset : An output image can be negative, so add offset to make it positive.

Usage

mitsuba -L error config_example/example.xml

We also included exhaustive example configurations with result image.

Citation

If you find this useful for your research, please consider to cite:

(TBA)