ADR-0037: Enhanced composes the default sky; Automatic and Manual expose it photographically

Status: accepted · 7 Sep 2026. Camera policy, processing and surface-light separation are implemented and verified. The camera plan records image and runtime acceptance, including the limits of each measurement. Supersedes the default-image preservation requirement in ADR-0031, the ordinary-view daylight omission policy in ADR-0032, and the bible's two-mode camera direction. Their implementation measurements remain valid for the responses they tested.

Context

The default camera needs to show detailed bright worlds against a visible star field and diffuse Milky Way. Natural preserves a production calibration and integrated star sprites, but its ordinary daylight response hides the diffuse galaxy. The engine consequently omits that volume in daylight views.

The M4 comparison makes the conflict concrete. A 2,400 s exposure reveals the galaxy and clips Earth; 1/40,000 s preserves Earth and loses the faint field at the same pose, aperture and ISO. The 26.5165-stop separation is useful evidence for a photographic camera. It does not satisfy the default art direction.

The requested reference is SpaceEngine's distinction between HDR, Auto and Manual. Its 2017 rendering explanation describes an HDR view with planets and stars visible together, alongside two photographic modes that differ in who sets exposure. This decision adopts that visual distinction, without prescribing SpaceEngine's rendering technique.

Decision

Enhanced is the default HDR composite; Automatic meters one photographic exposure, and Manual gives that exposure to the player.

Enhanced deliberately compresses the brightness differences between bright surfaces, stars and faint extended emission. Its normal Earth-orbit view shows planetary detail and recognizable galactic structure together, within the display's limits. Dark lanes stay dark relative to neighboring star clouds; bright stars retain their hierarchy; the planet remains the foreground subject. The result needs no long-shutter setup or galaxy-instrument preset.

Automatic and Manual share physical source brightness, lighting, optics and a bounded photographic response. Automatic meters scene light and adapts within the player's comfort limits. Manual uses aperture, shutter and ISO without meter-driven gain. Neither applies Enhanced's selective visibility treatment. Exposing for sunlit Earth or Luna suppresses faint stars. A view with little bright light permits Automatic to reveal them; Manual requires a change of settings. A night-side coordinate alone does not decide exposure. Bright limbs, planetshine, atmospheric scattering and glare can still affect the image.

There are three separate choices:

• Camera mode determines exposure and composite behavior.
• A tone curve determines the rendering of that mode's image. Changing a curve does not change metering, source light, or which mode is active. The controls expose one authored Enhanced look and the shared neutral photographic look. Imported Gentle and Crisp settings retain their explicit photographic shoulders.
• Display output determines gamut and available luminance headroom. Enhanced works on ordinary SDR sRGB displays. Display P3 is a gamut, and extended luminance is a separate capability, as distinguished by CSS Color HDR.

The interface calls the default Enhanced, with HDR composite in its description. HDR output names the separate display setting. Automatic's readout states metered exposure; Manual states the lens exposure; Enhanced states its composite processing instead of claiming one physical EV describes the whole image. A fixed diagnostic or cinematic exposure identifies its override in the readout.

resolveCameraPolicy in packages/rendering resolves selected mode, response style, effective exposure control and any staging override. ExposureMeter reports effective EV, gain relative to the lens, compensation and the override. A positive compensation brightens Automatic; it cannot add gain to Manual. Enhanced holds the 30,000 cd/m² surface calibration and declares its separate sky processing. Display peak and output negotiation do not select a mode.

Enhanced compresses diffuse sky luminance before the scene's half-float conversion. The owned sky target retains physical V-anchored radiance in nW m⁻² sr⁻¹; the composition reads that radiance and applies a presentation gain followed by bounded luminance compression. Uniform RGB scaling preserves chromaticity, zero remains zero, and the physical target stays available for photographic views and diagnostics. The full-resolution scene applies depth and silhouette coverage before the composed sky enters the common optics. Atmospheric transmission and modeled dust attenuation remain upstream of this visibility treatment. The lifted sky feeds glare and detector noise in Enhanced. Automatic meters only its photographic inputs.

The diffuse gain is 2^23, with a scene-luminance ceiling of 0.5 before the shared display response. The wider shoulder preserves contrast between faint background, dark lanes and bright star clouds. It changes no source radiance, physical cache or photographic exposure, and adds no passes or allocations.

Enhanced also owns the dark-body visibility lift, integrated star visibility and analytic solar core. Its near-field ambient and camera fill reach the hull and props. Photographic views disable both; only a script's explicit calibratedLight staging can retain them. Automatic and Manual use physical lighting and stellar flux with the same hue-preserving photographic response. A script can explicitly request calibrated lighting and the measured ACES staging look with calibratedLight; this is an authored override with a fixed exposure, and it releases when the script exits. Scripts do not rewrite the viewer's preference. Ordinary galaxy travel preserves the selected mode. Fixed photometric instruments request their stated photographic exposure explicitly.

The source model stays calibrated independently of camera mode. Catalog luminosities, geometric albedos, dust columns and emitted radiance do not change to make Enhanced attractive. Visibility processing belongs to the presentation chain and remains inspectable. It respects foreground occlusion, atmospheric transmission and dust extinction. It cannot paint a sky over a planet, restore stars hidden behind opaque dust, or manufacture illumination on an unlit body. Any dark-surface lift is an explicit Enhanced treatment.

A mapped surface takes reflectance from its texture and hue from a normalized tint. A mapless surface takes reflectance from its physical palette. The sphere, streamed ground and orbital reflectance bake share that convention; a bake contains no camera visibility gain. Enhanced applies its bounded dark-body gain once, at the scene material. Its 3% terrain and water fill is also visibility processing. Photographic modes retain modeled atmospheric scattering but apply neither that floor nor the dark-body gain.

Cloud maps remain thin weather shells. Their coverage clears continuously over the last quarter of a deck-altitude before the eye crosses the shell. One float64 eye altitude fades the entire oblate deck, including grazing rays, and follows render compression. Front-face culling cannot remove a bright veil in one frame. Distant coverage is unchanged, and every camera mode uses the same approximation. This is not a volumetric cloud model.

One sensor chain and the existing camera/lens producers remain in charge. Camera settings and adaptation are presentation state, outside the canonical world and its hash. ADR-0029 continues to govern the chain; ADR-0017 governs the lens. Pre-exposure, optical resource ownership, output negotiation and the numerical evidence in ADR-0031 remain useful. Its Natural image is a reference, not a release constraint.

Enhanced makes the diffuse sky part of ordinary gameplay cost. Eligibility cannot follow the Natural daylight predicate. The owned ordinary-view cache retains physical sky radiance and bounds its updates. Cache behavior and bake/live identity belong to ADR-0038. Photographic culling needs a conservative visibility bound through the actual optics and response, including glare, rather than an exposure label alone.

Automatic samples every fourth pixel in each axis into 64 logarithmic bins. An R8 instrument mask excludes samples covered by labels, orbit traces, landing marks and other instruments. The reducer excludes empty bin zero, trims the 40th–99.9th percentile interval and weights log luminance by light. A small lit disk can then dominate faint sky without an isolated hot pixel setting exposure. Comfort limits apply to retained physical luminance with the current settings, even when adaptation is held. Holding exposure leaves the mode Automatic.

Adaptation uses the engine's accumulated presentationTime, with frame deltas bounded at 0.1 s and time constants of 0.4 s toward bright and 3.5 s toward dark. Photographic time still places bodies and controls motion and detector noise. Camera cuts, mode changes and photographic-time scrubs reset meter history; generation checks discard asynchronous results from an earlier history. Manual and pinned frames ignore meter gain and repeat at a held instant.

Camera continuity is measured in universe coordinates with the render origin and its orientation. A 4,096 m origin rebase cannot become an exposure cut. The physical displacement and recent velocity distinguish a discontinuity from continuous travel; target, lens and held-time changes also invalidate history. Motion blur bypasses origin changes, camera cuts and time discontinuities, then resumes with continuous transforms. Exposure-key changes alone preserve that transform history. Defocus readbacks require the submitted lens and viewport, independently of exposure generations changed by a photographic scrub. Automatic reports Calibrating until it has a meter reading, then Metered or Held according to the adaptation setting.

The WebGL fallback supports Enhanced SDR and lens-controlled Manual. Automatic is visibly unavailable because that backend has no supported meter readback. A requested Automatic view uses a labeled Manual fallback while retaining the selected preference. A fixed calibration is never reported as metered exposure.

The preference owner migrates valid Composite + Natural to Enhanced, the other Composite curves to Automatic, and Direct to Manual. Natural maps explicitly to the neutral photographic look; Gentle and Crisp preserve their shoulders. White balance, adaptation rate and comfort limits survive. The lens preference retains aperture, shutter and ISO. Migration is written through state/preferences.ts; malformed imports are rejected without resetting the current selection.

Alternatives considered

Rename Natural and retain its behavior. This leaves bright planets and the diffuse galaxy mutually exclusive and preserves the wrong performance premise.

Raise one global exposure or brighten the galaxy field. The first clips the foreground; the second corrupts calibration for every consumer. Enhanced needs a declared presentation response with enough precision to retain faint light until that response can use it.

Make photographic exposure the default. Scientifically useful, but it does not meet the requested composition. Automatic and Manual provide it.

Require an HDR monitor. The default composition must work in sRGB SDR. Extra display headroom improves highlights without deciding camera behavior.

Keep Direct and Composite as additional player modes. This duplicates exposure policy and tone-curve choices. Their serialized settings need an explicit migration; linear clipping can remain a developer diagnostic.

Consequences

Enhanced spends processing and cache memory to retain faint structure beside bright foregrounds. One global exposure cannot cover the 26.5165-stop M4 comparison without losing either the galaxy or surface detail. The physical field remains independently calibrated, and its diagnostics bypass Enhanced.

Version 2 pictures and shot=2 URLs record camera processing without adaptation history or display hardware. Version 1 restores Enhanced while preserving its pose, photographic time and lens; historical image equality is not promised. ADR-0033 owns that portable format.

Numerical tests establish exposure arithmetic, strict migration, histogram behavior, physical continuity and surface-light separation. Image acceptance is a separate question from instrumented timing, and both are recorded rather than asserted: sixteen matched mode triplets, two transition recordings and four descent casts are inspected in CONTEXT.md, and the complete-frame operating points, the two journeys and the optical costs are in the performance plan. Enhanced draws the sky in ordinary gameplay, so those are whole-frame figures at named points and not a claim of sustained 60 fps — dense ground at a native Retina buffer runs around 30–34 fps. The source's smooth dust morphology remains an approximation; a camera response cannot recover missing structure. ADR-0038 owns the resolved-star and diffuse-sky implementation.