About SEGI

SEGI has moved to GitHub!

SEGI has moved to GitHub and is free to download and open-source! If you purchased SEGI on the Asset Store on August 1st, 2017 or later, you will be granted a refund upon request via the Contact page.

SEGI is a voxel-based Global Illumination effect that aspires to provide 100% dynamic Global Illumination to Unity games and applications. Since it requires no precomputation, SEGI can bring GI to certain situations where precomputed solutions like Enlighten cannot!

SEGI provides indirect lighting and glossy reflections from a single directional light, the sky, and any emissive materials in the scene. In the future, SEGI will support indirect lighting from point and spot lights. SEGI calculates indirect light visibility for soft indirect shadows, and also calculates soft sky light shadows. It can render either a single bounce or infinite bounces of indirect light.

If you want to report an issue, make sure it’s not in the list of known issues below. You can either post in the Unity Forums thread, or visit the Contact page.

Gallery

Demos

sponza demo

Sponza Demo

Demo of SEGI Beta v0.8 in the Crytek Sponza Atrium.

Bloom, tonemapping, anti-aliasing, and SEGI only.

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sponza demo

Low-Poly Demo

Demo of SEGI Beta v0.8 in a low poly scene.

Bloom, tonemapping, anti-aliasing, and SEGI only.

Download
sponza demo

Labyrinth Demo

Demo of SEGI Beta v0.8 in procedurally generated environment.

Bloom, tonemapping, anti-aliasing, and SEGI only.

Download

Compatibility

As this is the first beta version of SEGI, compatibility is limited. SEGI has only thoroughly been tested on a Windows PC; behavior on other platforms is unknown. Improving compatibility is of high priority. SEGI requires DX11. SEGI is not compatible with mobile devices, and probably never will be.

Known Issues

  • Infinite bounces can be slow in some complex scenes
  • Artifacts with temporal sampling and moving objects
  • Incompatible with forward-rendered objects (deferred only)
  • Light cookies on Directional Lights do not affect GI
  • Point and spot lights do not contribute to GI
  • Possible stuttering while playing in editor with the camera inspector visible
  • Undefined behavior with VR
  • Undefined behavior with multiple instances of SEGI
  • Does not work with orthographic camera (since deferred rendering is disabled for orthgraphic cameras)
  • Some voxels are black/too dark when voxel AA and infinite bounces are both enabled
  • Slight changes in positions of some objects in the volume can cause large lighting differences

Current Limitations

There are two causes of light leaking under the hood of SEGI. The first is an inherent limitation of cone tracing. The premise of cone tracing is that for each traced “ray”, instead of simply sampling a point of information, you get to sample an area of pre-combined information. This keeps rays that are traced in different directions more coherent and allows for tracing far fewer rays to get a smooth result. Simply put, cone tracing samples blurred data.


This diagram compares naive ray tracing (left) with cone tracing (right)

Now, what happens when we have a one-voxel-wide occluder in front of that light data?

As you can see, with naive “brute force” sampling, each ray encounters full opaque black before it reaches the illuminated voxels, so no light gets through. With cone tracing, however, data is blurred which smears the occluder and the light information such that rays do not encounter full opaque black before reaching the illuminated voxels.

The other cause of light leaking is a lack of directional light information in the voxel data. This means that, instead light bouncing forward off an illuminated surface, it bounces in all directions. This problem is helped with the Inner Occlusion Layers property and GI Blockers (see Section 4.2 of the User Guide), but is not solved completely. In the future, multiple already explored options will be considered regarding storing and reading directional voxel data to resolve this issue.

Mostly because of the light leaking discussed above, SEGI can struggle with indoor/outdoor hybrid scenes, especially with interiors that have thin bright walls. The use of GI Blockers (discussed in the User Guide) can help.
Currently, SEGI only uses a single voxel volume to store GI data. This means that large scenes or scenes with greatly varying object scales are not handled well. In the near future, voxel volume cascades (akin to shadow cascades) will be used to extend the GI distance and influence whilst keeping high-density data where it counts–near the camera.
SEGI completely revoxelizes everything inside the GI voxel volume every frame. This obviously is not ideal, especially with mostly static scenes, because a lot of redundant work is being done. This issue will be investigated soon in order to find a way to reduce redundant voxelization and improve performance.
With SEGI, you have the option of leveraging temporal sampling in order to produce a smoother result at a reduced cost. This aspect of SEGI is still under construction and causes minor issues with moving objects. With SEGI v0.82 and Unity 5.4 or newer, velocity reprojection is used to vastly improve temporal sampling with moving objects. You can choose not to use temporal sampling to avoid these issues.

Changelog

  • Unity 5.5 support and compatibility with Unity 5.5’s inverted depth buffer functionality

 

  • Unity 5.4 Motion Vectors support for temporal sampling
    • When used with Unity 5.4 or newer, SEGI’s temporal sampling now takes advantage of Unity’s built-in Motion Vectors for a vast visual improvement on moving objects/characters!

 

  • Smarter voxel data encoding for faster voxelization and less memory usage
    • Using smart data encoding, voxelization requires fewer texture writes and reads and uses less memory for an average 1.5x voxelization speedup!

 

Development Roadmap

Many things are planned for the future development of SEGI, both specific and general. As well as fixing the known issues and limitations, these things are planned to be worked on in the future.

  • 100%
    Use velocity buffer to eliminate artifacts caused by moving objects with temporal sampling.
  • 100%
    Smarter voxel data encoding for reduced memory usage and faster voxelization.
  • 95%
    Voxel volume cascades for handling large scenes.
  • 20%
    Directional voxel data to prevent light leaking.
  • 80%
    Screen-space tracing for fine-scale indirect shadows (SSAO on steroids).
  • 25%
    Cubemap support for ambient/sky light.
  • 20%
    Indirect light from point and spot lights.
  • 10%
    Half-resolution reflection tracing with full-resolution resolve for faster reflections.
  • 0%
    Smarter voxelization for less redundant work.
  • 0%
    Cubemap/reflection probe fallback for reflections instead of uniform sky color.
  • 0%
    Extra occlusion layers to be material-specific instead of globally applied to all voxelized geometry.
  • 10%
    More simplistic and efficient switchable modes.
  • 0%
    Support for forward-rendered objects.
  • 0%
    Better close-proximity GI by storing voxelized geometry normals.
  • 5%
    Additional dominant cones for soft voxel shadows traced from point/spot lights.
  • 0%
    Improve smoothness of GI when stochastic (randomly jittered) sampling is disabled.
  • 0%
    Voxel data pre-calculation for static objects.
  • 0%
    Baking GI result for super-fast GI baking.
  • 0%
    Separate voxelization from light injection so lighting can be updated on static voxels.