Fixing Lighting Artifacts With Diffuse Probe Grids In O3DE

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Fixing Lighting Artifacts with Diffuse Probe Grids in O3DE

Hey guys! Having trouble with those pesky black squares and blotches when using Diffuse Probe Grids in O3DE? You're not alone! This article dives deep into the issue, offering potential solutions and workarounds to achieve smoother, more accurate lighting in your Open 3D Engine projects. Let's get started and fix those lighting gremlins!

Understanding the Diffuse Probe Grid Artifact Issue

The diffuse probe grid system in O3DE, while powerful, can sometimes introduce unwanted artifacts into your scene's lighting. These artifacts often manifest as black square blotches that appear around contours and connected surfaces. These blotches can be incredibly frustrating, especially when you're aiming for a polished, professional look. The problem seems to persist regardless of the probe spacing or ray count, suggesting a deeper issue at play.

One potential cause is the texture resolution of the probe grid itself. It appears that the resolution might be too low to accurately capture the nuances of the scene's lighting, leading to these blocky artifacts. Unfortunately, there doesn't seem to be a direct option to increase the texture resolution, making it a challenging problem to solve. This is especially noticeable when you switch to baked global illumination (GI), which amplifies these imperfections, making them even more apparent.

The core problem lies in how the diffuse probe grid interpolates lighting information. When surfaces intersect or are in close proximity, the probe grid might struggle to accurately represent the light transport, resulting in those characteristic black square artifacts. These issues are compounded when baking GI, as the baked lighting data further accentuates any pre-existing imperfections in the probe grid's representation of the scene.

Ultimately, these artifacts detract from the visual fidelity of your scene, undermining the benefits of using global illumination. Finding a reliable solution or workaround is crucial for achieving high-quality lighting in O3DE projects that utilize the diffuse probe grid.

Reproducing the Artifacts: A Step-by-Step Guide

To effectively troubleshoot and address this issue, it's essential to be able to reproduce it consistently. Here’s a simple guide to recreate the diffuse probe grid artifacts in O3DE:

  1. Set up the Scene: Start by creating a new scene in O3DE. Add a plane and a sphere to the scene. Make sure the sphere slightly intersects with the plane. This intersection is where the artifacts will be most visible.
  2. Add the Diffuse Probe Grid: Add a diffuse probe grid component to your scene. Adjust the probe spacing to a relatively small value to increase the density of the probes. This will help illustrate the problem, even if it doesn't eliminate it.
  3. Bake the Global Illumination: Bake the global illumination (GI) in your scene. This will activate the diffuse probe grid and allow it to contribute to the scene's lighting. Once the baking process is complete, you should start to see the artifacts appear.
  4. Observe the Artifacts: Examine the area where the sphere and plane intersect. You should notice black square artifacts and pinch-point blotches on the surfaces. These artifacts are the result of the probe grid's limitations in accurately capturing the lighting information in this area.
  5. Experiment with Settings: Try adjusting various settings related to the diffuse probe grid, such as the ray count and probe spacing. While these adjustments might slightly alter the appearance of the artifacts, they likely won't eliminate them entirely. This reinforces the idea that the issue is related to the underlying texture resolution or interpolation method of the probe grid.

By following these steps, you can reliably reproduce the diffuse probe grid artifacts and experiment with different solutions to mitigate them.

Expected vs. Actual Behavior: What Should We See?

Ideally, when using a diffuse probe grid, you'd expect a smooth and accurate representation of global illumination in your scene. This means no abrupt changes in lighting, no black square artifacts, and no noticeable blotches or pinch points on surfaces. The lighting should seamlessly blend across different objects and surfaces, creating a realistic and visually appealing environment.

Expected Behavior:

  • Smooth Lighting Transitions: Light should transition smoothly between different surfaces, without any visible seams or discontinuities.
  • Accurate Representation of GI: The diffuse probe grid should accurately capture the indirect lighting in the scene, including bounced light and color bleeding.
  • No Artifacts or Blotches: There should be no black square artifacts, pinch-point blotches, or other visual imperfections caused by the probe grid.
  • Consistent Lighting Quality: The lighting quality should be consistent across the entire scene, regardless of the complexity of the geometry or the proximity of different objects.

Actual Behavior:

Unfortunately, the actual behavior often deviates from these expectations. As described earlier, the diffuse probe grid can introduce various artifacts, including:

  • Black Square Artifacts: These are the most common and noticeable artifacts, appearing as black square blotches on surfaces, especially around contours and intersections.
  • Pinch Point Blotches: These are darker areas that appear where surfaces are close together, creating an unnatural and unappealing look.
  • Inconsistent Lighting: The lighting quality can vary depending on the density of the probe grid and the complexity of the scene, leading to inconsistent results.

This discrepancy between the expected and actual behavior highlights the need for improvements to the diffuse probe grid system in O3DE. Whether it's through increased texture resolution, improved interpolation methods, or alternative GI techniques, addressing these artifacts is crucial for achieving high-quality lighting in O3DE projects.

Potential Solutions and Workarounds

While a definitive fix for the diffuse probe grid artifacts might require engine-level changes, there are several potential solutions and workarounds you can try in the meantime:

  1. Increase Probe Density: Although it might not completely eliminate the artifacts, increasing the density of the probe grid (reducing the probe spacing) can sometimes help to reduce their severity. This essentially provides a finer-grained representation of the lighting in the scene.
  2. Adjust Ray Count: Experiment with different ray counts for the probe grid. Increasing the ray count can potentially improve the accuracy of the lighting calculations, but it can also increase the baking time.
  3. Modify Surface Geometry: In some cases, the artifacts might be more pronounced in areas with complex geometry or sharp angles. Simplifying the geometry or smoothing out the surfaces can help to reduce the visibility of the artifacts.
  4. Use Alternative GI Techniques: Consider using alternative global illumination techniques, such as screen-space global illumination (SSGI) or ray-traced global illumination (if your hardware supports it). These techniques might provide better results in certain situations.
  5. Post-Processing Effects: Apply post-processing effects, such as ambient occlusion or bloom, to help mask the artifacts. These effects can soften the lighting and make the artifacts less noticeable.
  6. Manual Lighting Adjustments: Manually adjust the lighting in the scene to compensate for the artifacts. This might involve adding additional light sources or tweaking the properties of existing lights.

Keep in mind that these are just potential workarounds, and their effectiveness may vary depending on the specific scene and the severity of the artifacts. It's important to experiment with different approaches to find the best solution for your project.

Providing Additional Information for Bug Reporting

When reporting a bug related to the diffuse probe grid artifacts, providing as much detail as possible is crucial for developers to understand and address the issue effectively. Here's the kind of information that's helpful to include:

  • Branch Information: Specify the name of the branch where you encountered the issue. If you're using a development or official branch, provide a link to the branch.
  • Commit ID: Include the commit ID from the o3de/o3de repository. You can obtain this ID by running the git rev-parse HEAD command in your Git repository. This helps developers pinpoint the exact version of the engine you were using when the issue occurred.
  • Hardware and Software Specifications: Provide detailed information about your desktop or device, including:
    • Device (e.g., PC, Mac, Laptop)
    • Operating System (e.g., Windows 10, macOS Monterey)
    • Operating System Version
    • CPU (e.g., Intel Core i7-10700K, AMD Ryzen 9 5900X)
    • GPU (e.g., NVIDIA GeForce RTX 3080, AMD Radeon RX 6800 XT)
    • Memory (RAM) (e.g., 16GB, 32GB)
  • Detailed Steps to Reproduce: Provide a clear and concise list of steps that developers can follow to reproduce the issue on their own machines.
  • Screenshots or Videos: Include screenshots or videos that visually demonstrate the artifacts. This can be extremely helpful for developers to understand the nature and severity of the problem.
  • Additional Context: Add any other relevant information that might help developers understand the issue, such as specific settings you're using, any modifications you've made to the engine, or any other observations you've made.

By providing this information, you can significantly increase the chances of the bug being resolved quickly and effectively. Let's work together to make O3DE the best it can be!

Conclusion

Dealing with diffuse probe grid artifacts can be a real pain, but hopefully, this article has shed some light on the issue and provided you with some potential solutions and workarounds. Remember to experiment with different settings, explore alternative GI techniques, and provide detailed bug reports when necessary. With a little patience and persistence, you can overcome these challenges and achieve stunning lighting in your O3DE projects. Keep creating and keep pushing the boundaries of what's possible! Happy developing, folks!