How do you combine ray tracing and rasterization in Blender for faster rendering?

1 Eevee vs Cycles

Blender offers two main rendering engines: Eevee and Cycles. Eevee is a real-time rasterization engine, designed for fast and interactive rendering. It uses screen-space effects, such as ambient occlusion, bloom, depth of field, and motion blur, to create realistic results. However, Eevee has limitations when it comes to global illumination, indirect lighting, and complex materials. Cycles is a ray tracing engine, designed for high-quality and photorealistic rendering. It calculates the light paths for each pixel, taking into account the physical properties of the materials and the environment. However, Cycles is slower and more computationally intensive than Eevee, especially for large and detailed scenes.

2 Combining ray tracing and rasterization

One way to combine ray tracing and rasterization in Blender is to use the hybrid rendering mode, which is available in Blender 2.93 and later versions. This mode allows you to use Eevee as the main renderer, but switch to Cycles for specific objects or effects that require ray tracing. For example, you can use Eevee for the background and the main objects, but use Cycles for a glass sphere or a mirror that needs accurate reflections and refractions. To enable the hybrid rendering mode, you need to go to the Render Properties panel, select Eevee as the render engine, and enable the Use Cycles option. Then, you can select the objects that you want to render with Cycles, and enable the Use Cycles option in the Object Properties panel.

3 Benefits of hybrid rendering

The main benefit of hybrid rendering is that it can reduce the rendering time and the memory usage, compared to using Cycles alone. By using Eevee for most of the scene, you can avoid the overhead of ray tracing for every pixel, and only use it for the parts that need it. This can also help you achieve a certain artistic style, by mixing realistic and stylized elements in the same scene. For example, you can use Eevee for a cartoon-like character, but use Cycles for a realistic water or fire effect.

4 Limitations of hybrid rendering

The hybrid rendering mode also has some limitations that you need to be aware of. First, it does not support all the features and settings of Cycles, such as adaptive sampling, denoising, motion blur, and some shaders and nodes. Second, it does not guarantee a seamless integration between the two renderers, as there may be some differences in lighting, shading, and antialiasing. Third, it may introduce some artifacts or glitches, such as black pixels, flickering, or noise, depending on the scene and the resolution. Therefore, you need to test and adjust your settings carefully, and check the final output for any errors.

5 Tips for hybrid rendering

To optimize your hybrid rendering workflow in Blender, you should use the Viewport Shading mode to preview the hybrid rendering in real time, and switch between Eevee and Cycles to compare the results and performance. The Render Region option can be used to render only a part of the scene. The Simplify option can reduce the number of samples, subdivisions, and particles for Cycles, thus improving rendering speed. Light Probe objects can be used to bake the indirect lighting for Eevee, and improve the quality and consistency of lighting. Finally, you can use the Compositor to add post-processing effects like color correction, glare or vignette to enhance the final image.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?