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God rays

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God rays is a term with two separate meanings relevant to virtual reality (VR) and augmented reality (AR). In computer graphics it is a common name for crepuscular rays, the visible shafts of light and shadow that form when light passes through a scattering medium such as haze or fog, and for the volumetric light scattering techniques that reproduce them in rendered scenes.[1] In VR hardware the same name is used for an optical artifact: streaks or flares of light that appear to radiate from bright, high-contrast elements when the image is viewed through a headset's lenses, an effect most closely associated with Fresnel lenses.[2]

The rendering effect adds realism to virtual scenes but is costly to compute, because light scattered toward the viewer has to be integrated through the volume in front of every pixel.[3] The lens artifact became a familiar complaint with the Fresnel optics of first-generation consumer headsets such as the Oculus Rift and HTC Vive, and it was greatly reduced in later headsets that moved to non-Fresnel pancake lenses.[4][5] Pancake optics have stray-light problems of their own, including glare and ghost images caused by multiple surface reflections inside the folded light path.[6][7]

Reviewed 17 October 2026. Checked all citations added in October 2026 (WMO Cloud Atlas, NASA APOD, ATI paper text, Henyey-Greenstein and Luo et al. Crossref records and abstract, Hillaire 2015 abstract, Oculus dynamic-draft patent, Road to VR Quest Pro, Bigscreen Beyond, Beyond 2 and Quest 3S articles, Meta Connect 2022 blog, KGOnTech) against their sources; earlier text was checked on 2026-09-29. About review dates.

Crepuscular rays in nature

In the real world, objects are not seen through a vacuum: the emission, absorption and scattering of light in the medium between the observer and the object have to be taken into account.[1]

God rays occur when a space contains a dense mixture of light scattering media, like gas molecules, and objects that occlude the light will cast volumes of shadow that appear to create rays of light that emanate from the light source (figure 1).[1] This phenomenon is also known as crepuscular rays, sunbeams, star flare, sunburst, or light shafts. In the field of 3D graphics development it is called Volumetric Light Scattering, in which the natural effect is replicated digitally. According to Tweak3D's 3D Dictionary, the general term of volumetric lighting is defined as "the capability of light to give the effect of passing through an actual three dimensional medium such as fog, dust, smoke, steam, and other gasses."[8][9]

The name "crepuscular" refers to the times at which the rays are typically seen, sunrise and sunset. The shadowed bands between the rays are cast by clouds or mountain tops that block sunlight or moonlight, and the light has to be scattered by airborne dust, aerosols, water droplets or air molecules for the contrast between lit and shadowed air to become visible. Seen from the ground, the rays appear to fan out from the Sun, but they are in fact parallel; the divergence is an effect of distance and perspective.[10] Mitchell's chapter in GPU Gems 3 makes the same point for rendering: in sunlight the shadow volumes are effectively parallel but appear to spread out from the Sun in perspective.[1]

The World Meteorological Organization's International Cloud Atlas describes crepuscular rays as dark bluish streaks and light beams that radiate from the Sun during twilight, the streaks being the shadows of clouds at or below the horizon. The atlas applies the same name to shadowed bands cast by clouds at any time of day and to sunlight passing through gaps in low cloud and made visible by water or dust. It also notes that the beams and shadows occasionally cross the sky and become visible again at the antisolar point, the point in the sky directly opposite the Sun.[11] These converging bands are called anticrepuscular rays. A 2026 NASA Astronomy Picture of the Day explanation describes sunlight partially blocked by a cloud after sunset producing patterns of light and shadow that cross the sky in parallel lines and, by perspective, appear to converge on the opposite horizon, like distant railway tracks.[12]

Volumetric light scattering in computer graphics

1. God rays (Image taken from Engelhardt and Dachsbacher, 2010)

History

Mitchell's survey traces the rendering of these rays to non-real-time work that used a modified shadow volume algorithm, followed by a method for multiple light sources. Real-time rendering of god rays was then researched in 2002 with a slice-based volume-rendering technique and in 2004 with hardware shadow maps, and an alternative real-time method, inspired by research from 2001, uses polygonal volumes.[1]

The shadow volume method is Nelson Max's 1986 SIGGRAPH paper "Atmospheric illumination and shadows", which reorganized Frank Crow's shadow volume algorithm to find the illuminated regions of space in front of each visible surface and add the light scattered by the atmosphere there, so that "when the atmosphere is partly in shadow, columns of scattered light will be visible".[13] The multiple-light approach is the 1987 shading model of Tomoyuki Nishita, Yasuhiro Miyawaki and Eihachiro Nakamae, which accounted for the luminous intensity distribution of each light source, shadows cast by obstacles and particle density, and computed the intensity at the viewpoint by integrating the light scattered between the viewpoint and each visible point.[14] The 2002 real-time method, by Yoshinori Dobashi, Tsuyoshi Yamamoto and Nishita, stored precomputed intensities of scattered light in look-up tables and used them as textures, so that graphics hardware could render effects such as spotlight beams and shafts of light at interactive rates.[15] Mitchell's chapter credits the shadow-map approach to a 2004 Game Developers Conference presentation and the polygonal-volume approach to work by James (2003) building on Radomir Mech (2001).[1]

Physics and the single-scattering model

The creation of realistic images is an important research subject in computer graphics. It is therefore necessary to know the properties of light, and a good grasp of the natural phenomenon of crepuscular rays in order to translate it properly to the virtual imagery.[15] Light is affected by the electromagnetic fields of different kinds of particles, which may result in the absorption of the light or scattering it in another direction.[16] As light goes through a media, there can be also emission, which is radiating electromagnetic energy. Since a photon can have multiple scattering events, complete equations taking into account this are hard to solve. In real-time rendering a single scattering model is used that assumes that the light was scattered only once before, making it easier to compute.[17]

Mitchell describes the underlying problem as the "intractable nature of the radiative transport equation", which accounts for emission, absorption and scattering; real-time renderers therefore usually make simplifying, homogeneous assumptions about the participating medium.[1] The Intel sample notes that for air, emission and absorption can be neglected, and that scattering affects a scene in two ways: part of the light leaving an object is scattered out of the view ray, while sunlight is scattered into it toward the camera, together producing aerial perspective.[17]

Hoffman and Preetham describe Earth's atmosphere as having two main classes of scatterers. The gas molecules of clean, dry air are much smaller than the wavelength of light and follow Rayleigh scattering, whose scattering coefficient is proportional to 1/λ4, so shorter (bluer) wavelengths are scattered far more than longer ones. Aerosols are larger particles described by G. Mie's 1908 theory, which is complex in the general case; the paper gives the phase function of L. G. Henyey and J. L. Greenstein as an approximation to the Mie phase function, with tables computed directly from Mie theory as another option. In their account, daytime in-scattered light is mostly blue because of Rayleigh scattering, but bright white in directions adjacent to the Sun because of Mie scattering.[16] Henyey and Greenstein introduced their function in a 1941 paper in The Astrophysical Journal.[18]

Real-time rendering techniques

Volumetric light scattering as well as other illumination effects such as indirect lighting, soft shadows, or caustics enhance the realism of rendered scenes and add polish. There is a number of ways that light shafts can be used like rays filtering through a forest canopy, light beams on a foggy night, or shafts of light shining through clouds, for example.[19][3] While rendering crepuscular rays and other light effects provides an enhancement of the realism in virtual scenes, it comes with a cost by increasing the computational demand for interactive applications. With participating media, light does not only interact with the surfaces in the virtual scene: as Engelhardt and Dachsbacher put it, scattering events occur at every point in space, which requires costly integration of the light scattered toward the observer. Fast rendering methods are therefore needed for interactive applications.[3][15] Engelhardt and Dachsbacher (2010) write that rendering volumetric lighting effects is "typically done using ray marching which is too expensive for every pixel on the screen for interactive applications" and propose "a rendering technique for textured light sources in single-scattering media, that draws from the concept of epipolar geometry to place samples in image space: the inscattered light varies orthogonally to crepuscular rays, but mostly smoothly along these rays. These are epipolar lines of a plane of light rays that projects onto one line on the image plane. Our method samples sparsely along epipolar lines and interpolates between samples where adequate, but preserves high frequency details that are caused by shadowing of light rays. We show that our method is very simple to implement on the GPU, yields high quality images, and achieves high frame rates."[3]

Screen-space post-process

The best-known real-time approximation is Kenny Mitchell's post-process method, published in GPU Gems 3 while he was at Electronic Arts. It works on the finished image rather than on scene geometry. For each pixel, samples are taken along a line toward the light's position on screen, and the proportion of samples that reach the bright light region rather than an occluder estimates how much of the light is blocked. The samples are summed with artist-controlled weight, exponential decay and exposure factors, so each shaft fades smoothly away from the light, and multiple lights can be handled with additional passes.[1] To avoid streaks caused by surface textures, occluding objects can first be rendered black and untextured in an occlusion pre-pass.[1] Mitchell lists the method's limitations: shafts from background objects can appear in front of foreground objects when the light source is relatively near, shafts flicker when occluders cross the edge of the image because they fall outside the range of visible samples, and samples spread far apart when the viewer faces perpendicular to the light, which can be reduced by clamping the light's screen position or fading the effect out.[1] Moreau-Mathis's 2014 tutorial, which he says was largely inspired by the NVIDIA chapter, implements the same two steps (a light scattering pass with obstacles drawn black, then a shader applied to a full-screen quad) in both GLSL and HLSL.[8]

Unreal Engine exposes two variants of this idea as "light shafts" on directional lights. Its documentation describes the effect as simulating "the real world effect of crepuscular rays". The occlusion method builds a mask from the depths of on-screen objects, blurs it away from the light and uses it to mask fog and atmosphere, while the bloom method captures scene color around the light and blurs it radially outward. Epic gives costs of 0.5 ms for occlusion and 0.68 ms for bloom on a single light at 1080p on a GeForce GTX 680.[20]

Accelerated ray marching

Physically based methods integrate in-scattered light along each view ray while testing visibility to the light, and a series of papers reduced the cost of doing this with shadows. Chris Wyman and Shaun Ramsey (2008) combined ray marching with shadow volumes so that samples are placed only where needed, and extended the method to textured lights.[21] Ilya Baran, Jiawen Chen, Jonathan Ragan-Kelley, Fredo Durand and Jaakko Lehtinen (2010) observed that in a suitable coordinate system the visibility function has a regular structure, and used partial sum trees to compute the scattering integrals in homogeneous single-scattering media, reporting CPU speedups of 17 to 120 times over ray marching.[22] Chen, Baran, Durand and Wojciech Jarosz followed in 2011 with a GPU method based on 1D min-max mipmaps.[23] Intel's 2012 "IVB Atmospheric Light Scattering" sample combined Engelhardt and Dachsbacher's epipolar sampling, to cut the number of ray-marched samples, with Chen and colleagues' min-max mipmaps, to speed up the ray marching itself, to reach interactive frame rates on Intel processor graphics.[17]

Later work applied the same ideas to simulators. A 2020 paper in PLOS ONE describes an adaptive framework for flight simulators that uses more samples near the camera and fewer far away, an improved epipolar sampling step, culling of samples blocked by obstacles, and interactive estimation of participating-media density for multiple light sources.[24]

Frustum-aligned volumetric fog

Another approach computes scattering in a low-resolution 3D grid aligned with the camera frustum. Bartlomiej Wronski of Ubisoft Montreal presented this "Volumetric Fog" technique, developed for Assassin's Creed IV: Black Flag, at SIGGRAPH 2014 as a unified compute-shader solution for fog, smoke and haze of varying density, "god rays", light shafts and volumetric shadows; the talk abstract states that it supports multiple lights, works with deferred and forward shading, and is faster than existing ray-marching approaches.[25] Unreal Engine's Volumetric Fog, an option of its Exponential Height Fog component, computes participating-media density and lighting at every point in the camera frustum using camera-aligned volume textures with heavy temporal reprojection. Epic's documentation gives its cost as 1 millisecond on PlayStation 4 at High settings and 3 milliseconds on an NVIDIA GTX 970 at Epic settings.[26] In the Advances in Real-Time Rendering in Games course at SIGGRAPH 2015, Sebastien Hillaire of Electronic Arts presented a framework for the Frostbite engine that unified different representations of participating media, such as particles and large-scale depth fog, under physically based parameters. It used a cascaded extinction volume into which particles are voxelized, a volumetric shadow map that can cast shadows from any light according to every volumetric element in the scene, and a final media rendering step; the abstract says the framework "will be used for all games powered by Frostbite in the future".[27]

Use in VR applications

The processing budget of standalone headsets limits how much of this effect VR games can use. In a 2023 Meta blog post about games updated for the Meta Quest 3, Michael Wentworth-Bell, founder and creative director of Digital Lode, said that on the Meta Quest 2 the studio "got a hint of" this atmosphere in Espire 2, whereas the Quest 3 "actually allowed us to add atmospheric particles and the effect of volumetric lighting", with hundreds of particles through a level. Digital Lode built the effect with Unreal's Niagara visual effects system.[28]

God rays as a headset lens artifact

Appearance

In headset reviews, "god rays" describes a lens artifact rather than a rendered effect. Road to VR's Ben Lang describes it as "a visual artifact that's especially prominent with high-contrast elements (like white text on a black background) which appears to show streaks of light radiating outward from the center of the lens", and notes that it is a lens-dependent issue that more display resolution does not fix.[2] Writing about the Oculus Rift and HTC Vive in 2018, Road to VR's Scott Hayden said users notice "fine concentric circles" when looking through the lenses, "creating something many call 'God Rays'", which are "especially egregious when viewing high contrast scenes".[4]

Lang's 2019 review of the Valve Index separates two effects that users often group together. God rays, in his usage, are the lens flare-like light that seems to emanate directly from bright objects against darker surroundings, such as white text on a black background. Glare, which he equates with internal reflections, is broader scattered light that spreads around the field of view more globally. Both disappear in low-contrast scenes.[29] UploadVR, reporting on a modified Oculus Go by Palmer Luckey, described god rays as "internal reflections seen as distracting visual artifacts in VR".[30]

Causes

Fresnel lenses collapse the curvature of a conventional lens into concentric ridges, which makes them thinner and lighter, but they are known to introduce artifacts such as god rays and edge glare.[31] A 2018 SPIE paper by Melissa Geng and colleagues states that Fresnel lenses are used in most commercial VR near-eye displays partly because of their low weight and volume and acceptable pupil swim, but "can suffer from significant stray light artifacts"; smooth refractive lenses give lower stray light at the cost of much greater size and weight.[32] A 2022 study presented at the Society for Information Display symposium examined the causes of Fresnel-lens stray light in VR equipment through experiments and simulation and concluded that the edges of the Fresnel lens are the biggest single factor.[33]

In the terms used by an Oculus patent, each Fresnel structure (ring) of the lens has a slope facet, which refracts the light, and a draft facet, each tilted at its own angle from a reference axis.[34] Patents from Lockheed Martin, Sony and Facebook describe the mechanism in more detail. A Lockheed Martin patent on Fresnel lenses states that "the concentric draft facets create subtle but visible rings that are perceivable to a user, especially in the periphery of the lenses", and proposes angling each draft facet according to the lens material's refractive index to reduce their visibility.[35] A Sony Interactive Entertainment patent says that "a flare which extends toward a center of a lens is generated in an image visually recognized through the Fresnel lens in some cases", caused by light passing through the tops of the ridges.[36] A Facebook patent refers to "diffractions and other stray light artifacts associated with Fresnel structures".[37] Reflections from inside the headset also contribute: Luckey said that changing the Oculus Go's gray facial interface to black reduced god rays because less light reflects off it.[30]

Mitigation

Several approaches have been proposed or used. Facebook's patent "Hybrid Fresnel lens with reduced artifacts" (US 10,133,076), filed on 13 September 2016 and granted on 20 November 2018, gives the lens a smooth, non-Fresnel center region so that diffraction from Fresnel structures is reduced or eliminated where the user usually looks, with Fresnel ridges kept in the periphery to save weight.[37][4] The patent is now assigned to Meta Platforms Technologies.[37] A companion Oculus patent by the same three inventors, "Dynamic draft for Fresnel lenses" (US 10,025,101), filed the same day and granted on 17 July 2018, varies each ring's draft angle with its distance from the lens center. In one embodiment the draft angle is chosen so that the draft facet runs parallel to the light refracted by the slope facet, so that this light does not strike the draft facet, which the patent says reduces stray light and the resulting optical artifacts.[34]

Sony's US patent 10,641,931, filed in February 2017 and granted in May 2020, adds a light-absorbing portion to the Fresnel lens to suppress this flare; Road to VR described it as applied to surfaces that do not contribute to the lens shape, such as the back sides of the ridges.[36][2] Road to VR noted in 2022 that it was not known whether the method was practical for mass production or would be used in the PlayStation VR2.[2]

Headset makers also refined the Fresnel design itself. Oculus said at its October 2017 announcement of the Oculus Go that the headset's "next-generation lenses" offered "a wide field of view with significantly reduced glare".[38] UploadVR later wrote that the Go's lenses "already have greatly reduced god rays compared to the Oculus Rift".[30] Road to VR noted after trying the Go that its new lenses were Fresnel.[39]

The larger change came with non-Fresnel optics. Pancake lenses are polarization-based optics without ridged Fresnel surfaces. Road to VR's reviews of pancake-lens headsets report far fewer god rays than in Fresnel models (see table).[5] Geng and colleagues note the trade-off: polarization-based pancake optics give good resolution and pupil swim in a compact form, but generally have low light efficiency and poor image contrast because of severe ghosting.[32]

Content can also help. Because both god rays and glare fade in low-contrast scenes, Lang suggested that developers can reduce them by avoiding high-contrast elements, citing Lone Echo as the leading example.[29]

Glare in pancake optics

Pancake lenses remove the Fresnel ridges but not stray light. A 2024 Optics Express paper by Zhenyi Luo, Yuqiang Ding, Qian Yang and Shin-Tson Wu describes pancake optics, also called polarization-based catadioptric systems, as widely used in VR and mixed reality headsets for their compact form and image quality. The authors write that the folded design lowers optical efficiency to 25% because it uses a half mirror, and that it suffers from ghost images caused by stray light from multiple surface reflections and imperfect polarization control. They traced the light paths of these ghosts by experiment, analyzed them by simulation and investigated how the incident angle affects the intensity of each ghost.[6]

Reviewers describe the visible result as a different kind of artifact from Fresnel god rays. In his 2023 review of the Bigscreen Beyond, which uses tri-element pancake lenses, Ben Lang of Road to VR found "a lot of glare in high contrast scenes", which he judged not quite as bad as most Fresnel optics. He wrote that Fresnel lenses tend to create god rays that emanate from specific objects in the scene, while the Beyond's glare appears less directly attached to what is in the scene.[7] Display analyst Karl Guttag attributed the "glow" that many Apple Vision Pro users reported, particularly when watching movies, to unwanted reflections in its pancake optics, and wrote that these internal reflections cancel out the inherent high contrast of its OLED displays.[40] Glare can also come from outside the headset: Road to VR's Meta Quest Pro review noted that the open-sided design admits outside light that causes glare in the lenses, which the included light blockers mostly prevent except for light from below.[41]

Reported behavior in headsets

Headset Lens type (as reported) God rays and glare, as reported
Oculus Go Fresnel[39] Oculus claimed "significantly reduced glare"; UploadVR described god rays as greatly reduced compared with the Oculus Rift[38][30]
Valve Index Dual-element God rays improved over the HTC Vive and about on par with the Oculus Rift S; glare worse than Rift S, Vive and HTC Vive Pro, especially with large high-contrast elements[29]
Meta Quest Pro Pancake[42] "The painfully obvious god-rays seen emanating from bright objects on dark backgrounds are almost entirely gone"; outside light can cause glare through the open sides[41]
PlayStation VR2 Fresnel[31] "Still easy to spot god rays and some glare in high contrast scenes"[43]
HTC Vive XR Elite Pancake Reduced glare and god rays compared with the Meta Quest 2[44]
Meta Quest 3 Pancake, non-Fresnel "A huge improvement" in glare: "Gone are the painfully obvious god-rays"; only subtle glare even in scenes with extreme contrast[5]
Bigscreen Beyond Tri-element pancake[7] "A lot of glare in high contrast scenes", not quite as bad as most Fresnel optics and less directly attached to objects in the scene than Fresnel god rays[7]
Meta Quest 3S Fresnel (same lenses as Quest 2)[45] Added glare and a smaller sweet spot compared with the Meta Quest 3, on which these artifacts are "almost completely absent"[45]
Bigscreen Beyond 2 Pancake[46] Bigscreen says glare is reduced "by a good margin" compared with the original Beyond[46]
Steam Frame Pancake Significantly reduced god rays and glare for users coming from a Fresnel-era headset[47]

The original PlayStation VR used an aspheric non-Fresnel lens; Road to VR described the move to Fresnel lenses in its successor as a fairly big change.[31]

Measurement research

Researchers have begun to quantify the stray light behind these artifacts. A 2022 study in Applied Sciences by Hung-Chung Li, Meng-Che Tsai and Tsung-Xian Lee measured the visual threshold at which users perceive stray light in three VR headsets through psychophysical experiments, then trained machine-learning classifiers on wide-angle camera captures of the displays; all four algorithms tested reached about 90 percent accuracy in predicting perceived stray light.[48] A 2024 paper in the journal Virtual Reality by Chumin Zhao, Ryan Beams, Eshan Dahal and Aldo Badano measured veiling-glare point spread functions across the field of view of several headsets for medical use. At the center of the view, the HTC Vive Pro and HTC Vive Pro 2 showed less long-range glare than the Microsoft HoloLens 2 and Epson Moverio BT-300 AR headsets, but glare in the two VR headsets increased substantially toward the periphery, mainly because of optical aberration.[49] These studies measure stray light and glare in general and do not use the term "god rays".

See also

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Kenny Mitchell. "Chapter 13. Volumetric Light Scattering as a Post-Process". GPU Gems 3. NVIDIA. https://developer.nvidia.com/gpugems/gpugems3/part-ii-light-and-shadows/chapter-13-volumetric-light-scattering-post-process. Retrieved 2026-09-29.
  2. ↑ 2.0 2.1 2.2 2.3 Ben Lang (2022-02-08). "A Sony Patent Could Bring Next-gen Fresnel Lenses to PSVR 2". Road to VR. https://www.roadtovr.com/playstation-vr-2-psvr-2-fresnel-lenses-sony-patent/. Retrieved 2026-09-29.
  3. ↑ 3.0 3.1 3.2 3.3 Thomas Engelhardt, Carsten Dachsbacher (2010-02). "Epipolar sampling for shadows and crepuscular rays in participating media with single scattering". Proceedings of the 2010 ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games (I3D '10), pp. 119-125. ACM. doi:10.1145/1730804.1730823. https://doi.org/10.1145/1730804.1730823. Retrieved 2026-09-29.
  4. ↑ 4.0 4.1 4.2 Scott Hayden (2018-12-06). "Facebook Patents Hybrid Fresnel That Could Make VR Optics More Clear". Road to VR. https://roadtovr.com/facebook-patents-hybrid-fresnel-make-vr-optics-clear/. Retrieved 2026-09-29.
  5. ↑ 5.0 5.1 5.2 Ben Lang (2023-10-09). "Quest 3 Review - A Great Headset Waiting to Reach Its Potential". Road to VR. https://roadtovr.com/meta-quest-3-review-mixed-reality/. Retrieved 2026-09-29.
  6. ↑ 6.0 6.1 Zhenyi Luo, Yuqiang Ding, Qian Yang, Shin-Tson Wu (2024-04-24). "Ghost image analysis for pancake virtual reality systems". Optics Express, vol. 32, no. 10, pp. 17211. Optica Publishing Group. https://doi.org/10.1364/OE.523196. Retrieved 2026-10-17.
  7. ↑ 7.0 7.1 7.2 7.3 Ben Lang (2023-09-26). "Bigscreen Beyond - Promising but Incomplete, Just Like This Review". Road to VR. https://roadtovr.com/bigscreen-beyond-review-pc-vr-headset/. Retrieved 2026-10-17.
  8. ↑ 8.0 8.1 Julien Moreau-Mathis (2014-05-03). "God Rays? What's that?". Community Play 3D (Medium). https://medium.com/community-play-3d/god-rays-whats-that-5a67f26aeac2. Retrieved 2026-09-29.
  9. ↑ "The 3D Dictionary: Volumetric Lighting". Tweak3D. http://www.tweak3d.net/3ddictionary/3ddictionaryV.shtml. Retrieved 2026-09-29.
  10. ↑ "Crepuscular Rays, India". NASA Earth Observatory. NASA. 2011-10-30. https://eol.jsc.nasa.gov/Collections/EarthObservatory/articles/CrepuscularRaysIndia.htm. Retrieved 2026-09-29.
  11. ↑ "Crepuscular rays". International Cloud Atlas. World Meteorological Organization. https://cloudatlas.wmo.int/en/crepuscular-rays.html. Retrieved 2026-10-17.
  12. ↑ Cecilia Chirenti (2026-06-25). "Anticrepuscular Rays over Sicily". Astronomy Picture of the Day. NASA. https://science.nasa.gov/image-article/apod-2026-june-25-anticrepuscular-rays-over-sicily/. Retrieved 2026-10-17.
  13. ↑ Nelson L. Max (1986-08). "Atmospheric illumination and shadows". ACM SIGGRAPH Computer Graphics, vol. 20, no. 4 (SIGGRAPH '86), pp. 117-124. ACM. doi:10.1145/15886.15899. https://doi.org/10.1145/15886.15899. Retrieved 2026-09-29.
  14. ↑ Tomoyuki Nishita, Yasuhiro Miyawaki, Eihachiro Nakamae (1987-08). "A shading model for atmospheric scattering considering luminous intensity distribution of light sources". ACM SIGGRAPH Computer Graphics, vol. 21, no. 4 (SIGGRAPH '87), pp. 303-310. ACM. doi:10.1145/37402.37437. https://doi.org/10.1145/37402.37437. Retrieved 2026-09-29.
  15. ↑ 15.0 15.1 15.2 Yoshinori Dobashi, Tsuyoshi Yamamoto, Tomoyuki Nishita (2002-09). "Interactive rendering of atmospheric scattering effects using graphics hardware". Proceedings of the ACM SIGGRAPH/EUROGRAPHICS Conference on Graphics Hardware (HWWS '02), pp. 99-107. https://dl.acm.org/doi/10.5555/569046.569060. Retrieved 2026-09-29.
  16. ↑ 16.0 16.1 Naty Hoffman, Arcot J. Preetham. "Rendering Outdoor Light Scattering in Real Time". ATI Technologies developer paper (archived). ATI Technologies. https://web.archive.org/web/20211214093043/https://developer.amd.com/wordpress/media/2012/10/ATI-LightScattering.pdf. Retrieved 2026-09-29.
  17. ↑ 17.0 17.1 17.2 "IVB Atmospheric Light Scattering". Intel Developer Zone (archived). Intel. 2012-08-06. https://web.archive.org/web/20190820123811/https://software.intel.com/en-us/articles/ivb-atmospheric-light-scattering. Retrieved 2026-09-29.
  18. ↑ L. G. Henyey, J. L. Greenstein (1941-01). "Diffuse radiation in the Galaxy". The Astrophysical Journal, vol. 93, p. 70. https://doi.org/10.1086/144246. Retrieved 2026-10-17.
  19. ↑ "Rays". Digital Film Tools (archived). https://web.archive.org/web/20200516164645/https://www.digitalfilmtools.com/rays/. Retrieved 2026-09-29.
  20. ↑ "Using Light Shafts in Unreal Engine". Unreal Engine Documentation. Epic Games. https://dev.epicgames.com/documentation/en-us/unreal-engine/using-light-shafts-in-unreal-engine. Retrieved 2026-09-29.
  21. ↑ Chris Wyman, Shaun Ramsey (2008-08). "Interactive volumetric shadows in participating media with single-scattering". 2008 IEEE Symposium on Interactive Ray Tracing, pp. 87-92. IEEE. doi:10.1109/RT.2008.4634627. https://doi.org/10.1109/RT.2008.4634627. Retrieved 2026-09-29.
  22. ↑ Ilya Baran, Jiawen Chen, Jonathan Ragan-Kelley, Fredo Durand, Jaakko Lehtinen (2010-12). "A hierarchical volumetric shadow algorithm for single scattering". ACM Transactions on Graphics, vol. 29, no. 6 (SIGGRAPH Asia 2010). ACM. doi:10.1145/1882261.1866200. https://doi.org/10.1145/1882261.1866200. Retrieved 2026-09-29.
  23. ↑ Jiawen Chen, Ilya Baran, Fredo Durand, Wojciech Jarosz (2011-02). "Real-time volumetric shadows using 1D min-max mipmaps". Proceedings of the 2011 ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games (I3D '11), p. 39. ACM. doi:10.1145/1944745.1944752. https://doi.org/10.1145/1944745.1944752. Retrieved 2026-09-29.
  24. ↑ Tan S., Zhang J., Lin Y., Liu H., Yang M., Ge W. (2020-11-18). "Adaptive volumetric light and atmospheric scattering". PLOS ONE, vol. 15, no. 11, e0242265. Public Library of Science. doi:10.1371/journal.pone.0242265. https://doi.org/10.1371/journal.pone.0242265. Retrieved 2026-09-29.
  25. ↑ Bartlomiej Wronski (2014). "Volumetric Fog: Unified Compute Shader-Based Solution to Atmospheric Scattering". Advances in Real-Time Rendering in Games, SIGGRAPH 2014. https://advances.realtimerendering.com/s2014/index.html. Retrieved 2026-09-29.
  26. ↑ "Volumetric Fog in Unreal Engine". Unreal Engine Documentation. Epic Games. https://dev.epicgames.com/documentation/en-us/unreal-engine/volumetric-fog-in-unreal-engine. Retrieved 2026-09-29.
  27. ↑ Sebastien Hillaire (2015). "Towards Unified and Physically-Based Volumetric Lighting in Frostbite". Advances in Real-Time Rendering in Games, SIGGRAPH 2015. https://advances.realtimerendering.com/s2015/index.html. Retrieved 2026-10-17.
  28. ↑ "Best on Quest 3: Devs Making the Most of Our Most Powerful Headset Yet". Meta Quest Blog. Meta. 2023-10-09. https://www.meta.com/blog/best-on-quest-3-red-matter-2-walking-dead-saints-sinners-espire-2/. Retrieved 2026-09-29.
  29. ↑ 29.0 29.1 29.2 Ben Lang (2019-06-28). "Valve Index Review - The Enthusiast's Choice in VR Headsets". Road to VR. https://roadtovr.com/valve-index-review/. Retrieved 2026-09-29.
  30. ↑ 30.0 30.1 30.2 30.3 David Heaney (2018-12-17). "Palmer Luckey's Modified Oculus Go: Larger Battery, Improved Weight, Fewer God Rays". UploadVR. https://www.uploadvr.com/palmer-luckey-oculus-batter-god-rays/. Retrieved 2026-09-29.
  31. ↑ 31.0 31.1 31.2 Ben Lang (2022-02-05). "PSVR 2 Product Page Confirms Fresnel Lenses & Dual Displays". Road to VR. https://roadtovr.com/psvr-2-product-page-fresnel-lens-dual-display/. Retrieved 2026-09-29.
  32. ↑ 32.0 32.1 Melissa Geng, Brett J. Bryars, Brian M. Wheelwright, et al. (2018-05-21). "Viewing optics for immersive near-eye displays: pupil swim/size and weight/stray light". Proc. SPIE 10676, Digital Optics for Immersive Displays, 1067606. SPIE. doi:10.1117/12.2307671. https://doi.org/10.1117/12.2307671. Retrieved 2026-09-29.
  33. ↑ Haitao Huang, et al. (2022-06). "63-2: Research on Stray Light Affecting the Imaging of Fresnel Lens in Virtual Reality Equipment". SID Symposium Digest of Technical Papers, vol. 53, no. 1, pp. 827-829. Society for Information Display. doi:10.1002/sdtp.15620. https://doi.org/10.1002/sdtp.15620. Retrieved 2026-09-29.
  34. ↑ 34.0 34.1 Brian Wheelwright, Jacques Gollier, Melissa Geng (2018-07-17). "US10025101B2 - Dynamic draft for Fresnel lenses". Google Patents. Oculus VR. https://patents.google.com/patent/US10025101B2/en. Retrieved 2026-10-17.
  35. ↑ David A. Smith (2019-07-23). "US10359545B2 - Fresnel lens with reduced draft facet visibility". Google Patents. Lockheed Martin Corp.. https://patents.google.com/patent/US10359545B2/en. Retrieved 2026-09-29.
  36. ↑ 36.0 36.1 Shotaro Tada, Manabu Ishioka, Toshihiro Kusunoki (2020-05-05). "US10641931B2 - Fresnel lens and manufacturing method for Fresnel lens". Google Patents. Sony Interactive Entertainment Inc.. https://patents.google.com/patent/US10641931B2/en. Retrieved 2026-09-29.
  37. ↑ 37.0 37.1 37.2 Brian Wheelwright, Jacques Gollier, Melissa Geng (2018-11-20). "US10133076B2 - Hybrid Fresnel lens with reduced artifacts". Google Patents. Facebook Technologies, LLC. https://patents.google.com/patent/US10133076B2/en. Retrieved 2026-09-29.
  38. ↑ 38.0 38.1 "Pioneering the Frontier of VR: Introducing Oculus Go, Plus Santa Cruz Updates". Meta Quest Blog. Oculus (Meta). 2017-10-11. https://www.meta.com/blog/pioneering-the-frontier-of-vr-introducing-oculus-go-plus-santa-cruz-updates/. Retrieved 2026-09-29.
  39. ↑ 39.0 39.1 Ben Lang (2018-03-22). "GDC 2018: Our First Look at Oculus Go - Aiming for the Accessibility Sweet Spot". Road to VR. https://www.roadtovr.com/gdc-2018-oculus-go-first-look-aiming-for-the-accessibility-sweet-spot/. Retrieved 2026-09-29.
  40. ↑ Karl Guttag (2024-03-01). "Apple Vision Pro's Optics Blurrier & Lower Contrast than Meta Quest 3". KGOnTech. https://kguttag.com/2024/03/01/apple-vision-pros-optics-blurrier-lower-contrast-than-meta-quest-3/. Retrieved 2026-10-17.
  41. ↑ 41.0 41.1 "Quest Pro Review - Impressive Hardware With a Value Proposition That's Kind of a Mess". Road to VR. 2022-10-27. https://www.roadtovr.com/meta-quest-pro-review-value-proposition-mess/2. Retrieved 2026-10-17.
  42. ↑ "VR News at Meta Connect 2022". Meta Quest Blog. Meta. 2022-10-11. https://www.meta.com/blog/vr-news-connect-2022-meta-quest-pro/. Retrieved 2026-10-17.
  43. ↑ Ben Lang (2023-02-22). "PSVR 2 Review - Sony Takes Several Steps Forward for Consumer VR". Road to VR. https://roadtovr.com/psvr-2-review-ps5-sony-takes-several-steps-forward-consumer-vr/. Retrieved 2026-09-29.
  44. ↑ "Vive XR Elite Hands-on: Lightweight & Compact, But Shares Quest Pro's Woes". Road to VR. 2023-01-09. https://roadtovr.com/vive-xr-elite-hands-on-review-ces-2023/. Retrieved 2026-09-29.
  45. ↑ 45.0 45.1 Ben Lang (2024-09-25). "Quest 3S Hands-on: Quest 2 Visuals with Quest 3 Power at an Unbeatable Price". Road to VR. https://roadtovr.com/meta-quest-3s-hands-on-preview-connect-2024/. Retrieved 2026-10-17.
  46. ↑ 46.0 46.1 Scott Hayden (2025-03-20). "PC VR Headset Bigscreen Beyond 2 Promises Big Boost to Field-of-view & Clarity, Launching Next Month". Road to VR. https://roadtovr.com/pc-vr-bigscreen-beyond-2-fov-boost-release-date-price/. Retrieved 2026-10-17.
  47. ↑ Scott Hayden (2026-09-16). "Steam Frame Review - Power-user's Playground". Road to VR. https://roadtovr.com/valve-steam-frame-review/. Retrieved 2026-09-29.
  48. ↑ Hung-Chung Li, Meng-Che Tsai, Tsung-Xian Lee (2022-06-21). "A Stray Light Detection Model for VR Head-Mounted Display Based on Visual Perception". Applied Sciences, vol. 12, no. 13, 6311. MDPI. doi:10.3390/app12136311. https://doi.org/10.3390/app12136311. Retrieved 2026-09-29.
  49. ↑ Chumin Zhao, Ryan Beams, Eshan Dahal, Aldo Badano (2024-01-05). "Spatially dependent veiling glare degrades image quality in medical extended reality". Virtual Reality, vol. 28, no. 1, article 11. Springer. doi:10.1007/s10055-023-00893-x. https://doi.org/10.1007/s10055-023-00893-x. Retrieved 2026-09-29.
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