Computing a global illumination solution in real-time is still an open problem. We introduce Voxel-based Global Illumination (VGI), a scalable technique that ranges from real-time near-field illumination to interactive global illumination solutions. To obtain a voxelized scene representation, we introduce a new atlas-based boundary voxelization algorithm and an extension to a fast ray-voxel intersection test. Similar to screen-space illumination methods, VGI is independent of the scene complexity. Using voxels for indirect visibility enables real-time near-field illumination without the screen-space artifacts of alternative methods. Furthermore, VGI can be extended to interactive, multi-bounce global illumination solutions like path tracing and instant radiosity.