Key Features

High quality glossy specular reflections

For only a minor increase in runtime cost, Enlighten reflections on surfaces with medium to high roughness are now much more accurate. Compared with the previous release, the shape of specular highlights and overall specular brightness in Enlighten reflections now much more closely matches static reflections.

The additional cost to solve the cubemap varies depending on the indirect lighting resolution of the surrounding area, and we measured an average of 1.5x the previous cost on the Enlighten thread. To revert to the previous behaviour, specify r.Enlighten.Cubemap.UseLegacyFilter=1 in the Engine config file.

The images below show spheres with roughness 0.4, 0.6 and 0.8 in a location lit indirectly with bright lighting coming from directly above, which is now more accurately captured in Enlighten reflections. The image on the left was created with release 4.01, while the image on the right was created with release 4.02.

Halved cost of per pixel probe lighting

This release significantly reduces the runtime cost of per pixel probe lighting. The remaining per pixel probe lighting update work that previously ran on the CPU now runs in a compute shader on the GPU. The update process can now use 16-bit float internal buffers, which halves the cost of per pixel probe lighting updates.

In a scene with densely placed probes, probe memory usage is less than half of the previous release, and the render thread CPU cost for probe lighting updates is around half of the previous release. The cost of asynchronous updates for probe lighting on the Enlighten thread is also reduced by around 10%.

The 16-bit buffers are automatically enabled only in cooked game mode, and only when Available Probe Sample Methods in the Enlighten project settings is set to Per Pixel.

4.02.P1 Smoother per pixel probe lighting

Enlighten automatically adapts the per pixel probe lighting detail level as objects move closer or further away. When the lighting intensity differs significantly between detail levels the transition is now stable and smooth without obvious noise. When temporal anti-aliasing is enabled this transition is even smoother and often invisible.

The image on the left shows the transition in Release 4.02.R. The image on the right shows the smooth transition in 4.02.P1.

The images below show the same comparison with simple white materials to make the comparison more obvious.

4.02.P1 Smarter automatic probe placement

Enlighten uses invalid back-faces to detect areas that are outside the world and do not need indirect lighting. This release improves the way automatic probe placement detects areas that are outside the world, so that areas inside the world always have valid Enlighten indirect lighting. This eliminates broken Enlighten indirect lighting in areas that see invalid back-faces. The Enlighten indirect lighting in such areas may still be much less accurate and could appear unexpectedly bright or dark. We still recommend not to leave invalid back-faces visible in areas where accurate indirect lighting is important.

The new Probe Positions view mode highlights probes that see invalid back-faces. After you run Parameterize, we recommend to use this view mode along with the Radiosity Backfaces view mode to identify areas that see invalid backfaces. The images below show an area which sees an a visible invalid back-face. The Lit view shows acceptable Enlighten indirect lighting for the foliage meshes that are lit by per pixel probe lighting. The Radiosity Backfaces view mode shows the invalid back-face in orange. The Probe Positions view shows the locations of probes that see the invalid back-face in pink.

Efficient streaming of many instances

This release automatically shares Enlighten UVs between instances of the same mesh that have a slightly different scale. This prevents hitches when streaming a level that contains many instances of the same mesh. Compared with the previous release, the effective lighting resolution of an instance may increase or decrease slightly, but the overall resolution should be very similar. In some rare cases this change could cause lightmap lighting artifacts or even errors related to excessive lightmap resolution.

Independent radiosity simulations

This release makes it simple to quickly switch between two Enlighten data sets that have completely independent lighting. This enables a transition between two independent radiosity simulations without a loading screen. To make large scale changes to the entire world that affect radiosity, precompute multiple versions of the same world and switch between them. For a quick transition between two independently precomputed areas of the world, precompute multiple independent areas and switch between them.

Enlighten indirect lighting is only available for one independently precomputed area at a time. Other areas can still be visible and will only receive sky lighting, which works well for distant areas.

Use the Partition Name property of the Enlighten System Container actor to specify the Enlighten partition for the containing level. All levels with the same Enlighten partition name will be precomputed together. To change the active Enlighten partition in game mode, use the SetEnlightenActiveLevel blueprint function.

To specify the translation of a level at runtime, use the LoadLevelInstance function. All the levels with the same Enlighten partition name must be assigned the same translation. Rotation is not currently supported.

4.02.P1 Change radiosity update budget in game

On platforms with limited compute power available we recommend to limit the CPU budget assigned for asynchronous Enlighten radiosity updates. You can now change the budget while the game is running using a blueprint function.

Use the SetUpdateBudget Blueprint function to set the Enlighten radiosity update budget. This specifies the maximum CPU budget that can be used by Enlighten in a single update frame.

GeoRadiosity with scaled displays

To ensure compatibility with High DPI displays and Remote Desktop, GeoRadiosity now renders with D3D11 instead of D3D9. By default, the GeoRadiosity window is now automatically scaled to match the display scale setting of the display onto which the window is positioned.

It is not currently possible to resize or maximize the GeoRadiosity window. This functionality will be added in a future release.

Important changes

When the world was precomputed with the commandlet and Share Lightmaps Across Levels is disabled, the initial indirect lighting is no longer stored when a level is saved, to prevent a single frame flicker in per pixel probe lighting when the level is loaded.

The minimum size of probes shown in the Enlighten Probes view mode is now proportional to the minimum spacing between probes in the level. This ensures that when probe resolution is very high, probes shown in the visualisation do not appear too large.

Enlighten now skips some unnecessary precompute steps that could take a long time when the world contains a very large number of instances. These steps are only required to view the exported Enlighten scene within the GeoRadiosity debugging tool.

4.02.P1 The Enlighten precompute now reports a detailed warning message when an instance or probe region covers an extremely large volume of space. When this warning is reported, we recommend to reduce the Enlighten probe lighting resolution for the problem actor.

4.02.P1 The Enlighten precompute now reports a useful error message when a mesh requires too many lightmap pixels.

Fixed bugs

Fixed artifacts in per pixel probe lighting that could occur when a surface is exactly aligned with the automatic probe placement grid.
Fixed a crash during the CreateOutputProbeSet stage of the precompute that could occur in a world with very high probe resolution and dense geometry.
Fixed a bug in IntelTBB library which could trigger a precompute crash only with very specific build configurations.
Fixed a warning "Duplicated Enlighten ID" for a static mesh actor that was spawned by a Blueprint.
Fixed failure to report an error when the precompute memory limit was exceeded for a very complex scene.
Fixed a minor memory leak in the CreateLightTransport stage of the precompute that would cause unnecessary warnings.
4.02.P1 Fixed unexpected black areas in probe lighting that could occur around thin walls even when no invalid back-faces are visible.
4.02.P1 Fixed an extremely rare crash with the error "Detachment inconsistency" that could occur after the precompute of a very large world.
4.02.P1 Fixed a warning "Duplicated Enlighten ID" that would occur when two Static Mesh actors are spawned via Blueprint.
4.02.P1 Fixed a precompute hang which could occur in a scene which contains millions of foliage instances with Probe lighting mode.
4.02.P1 Fixed compile warning C4005 related to D3D headers reported when building Development Editor Win64 configuration.

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