This repository contains the code and data for a bachelor's thesis on combining photon mapping with ReSTIR Direct Illumination (DI). The renderer is written in C++ and supports global illumination techniques for realistic image synthesis.
- Photon Mapping for global illumination
- ReSTIR DI: Reservoir-based spatiotemporal importance resampling for efficient direct lighting, with both spatial and temporal reuse
- Three sampling techniques: Uniform, RIS (Reservoir Importance Sampling), and ReSTIR
- Path Tracing: Classic unbiased reference implementation
- Debug Mode: Visualizes photon-mapped virtual point lights (VPLs) using a kd-tree (nanoflann)
- TinyBVH: Fast BVH acceleration for ray-scene intersection
- Interactive and rendering modes
- All main parameters (e.g., sample counts, reuse settings) can be tuned in
constants.hpp
The renderer supports three direct illumination sampling techniques: Uniform, RIS, and ReSTIR. Uniform sampling selects lights randomly, RIS uses importance sampling with reservoirs, and ReSTIR extends this with both spatial and temporal reuse for improved efficiency and quality. In addition to these, a classic path tracing mode is available for unbiased reference rendering. The debug mode allows visualization of the photon-mapped VPLs and their spatial structure using a kd-tree built with nanoflann.
- C++20
- OpenMP (multithreading)
- SDL2 (windowing & input)
- GLM (math)
- TinyBVH (BVH acceleration)
- nanoflann (kd-tree for VPLs)
- stb_image, stb_image_write, tinyobjloader (assets)
- Python (evaluation scripts)
- C++20 compiler (MSVC, GCC, or Clang)
- CMake 3.28+
- SDL2
- Python 3 (for evaluation)
# Clone and build
cmake -S . -B build
cmake --build build --config Release
# Run the renderer from the build directory
./build/restir-vpl.exe- Place scenes/models in
objects/ - Output images are saved in
images/ - Use the debug mode to visualize photon-mapped VPLs and kd-tree structure
- Sampling technique and mode can be selected at runtime
- Tune parameters in
constants.hpp
The interactive live view supports real-time camera movement, sampling mode switching, and scene manipulation. Controls:
- W/A/S/D: Move camera forward/left/back/right
- Space / Left Ctrl: Move camera up/down
- Mouse: Look around (yaw/pitch)
- Shift: Sprint (move faster)
- 1/2/3: Switch sampling mode (1: Uniform, 2: RIS, 3: ReSTIR)
- 4: Enable path tracing mode
- V/B/N: Switch shading mode (V: Shading, B: Debug, N: Normals)
- Up/Down Arrow: Increase/decrease number of light samples (M)
- L: Spawn a point light at the camera position
- Backspace: Remove the most recently spawned point light
- G: Toggle global illumination (GI) on/off
- O/I: Save/load camera position to/from file
- Enter: Output a render with the current camera
- Esc: Exit live view