# LumaSphere features and lighting science

Canonical page: https://lumasphere-6588c810433f.herokuapp.com/about

## Projection

Equirectangular images map a 2:1 panorama to spherical longitude and latitude. Every pixel represents a direction. Rotation changes where the lighting falls in the renderer.

## Linear light and exposure

Lighting edits operate in linear RGB. An exposure change of EV stops scales radiance by 2^EV. LumaSphere provides exposure, color temperature, ambient-fill, and individual-source controls. Strong light sources can reach +30 EV. New focused emitters preserve total emitted energy when angular diameter changes. Hard sun and Focused lamp presets target 4:1 and 2:1 key-to-fill irradiance respectively on a surface facing the selected source, using the actual remaining fill. Smaller sources can produce sharper shadows in a renderer. These ratios are creative lighting targets, not measured HDR recovery.

## Automatic HDR lighting

New generated environments are reconstructed into estimated relative linear radiance. Daytime sky starts around 3 and ordinary surfaces around 0.18. Emitting regions share a 1.5:1 direct-to-fill budget, evaluated facing each source, with a compact 0.53-degree solar core and rapid falloff. Source peaks follow angular area and energy instead of a fixed extreme EV boost. Existing generated projects can use Rebuild HDR lighting; this replaces lighting edits and can be undone without using another image credit. Baseline region values and individual region-mask PNGs accompany exports. These values are estimates, not measured real-world luminance.

## Editable light masks

Scene controls include a light-mask editor for ovals, rotated rectangles, concave polygons, and freehand outlines. Drag handles, zoom in, inspect a black-and-white mask, and adjust inward edge feathering. The selected window or luminous surface drives the region adjustment in the preview and exported EXR. Masks wrap across the panorama seam and are saved with the project. Generated panoramas receive estimated semantic regions for sky, clouds, sun, windows, lamps, glowing materials, and surfaces. Brightness refinement excludes dark frames; automatic masks can contain holes and separate patches. Review labels and masks. Imported HDRs use brightness-only candidates.

## Preview and export

Panorama and material previews help evaluate the environment. A tone-mapped screen preview has a different purpose from the exported linear-light master. OpenEXR exports use 32-bit floating-point channels. Image generation is available up to 2K; larger exports resample the source rather than create measured detail.

## Provenance and limits

The app records generation and lighting assumptions and distinguishes source, generated, and edited content. Measurements can anchor lighting, but a single photograph and AI estimates do not establish measured scene radiance. Browser project edits remain on the device; account allowances and saved generated results are stored on the server.

## Navigation

- [Photo to HDRI Generator — 32-bit EXR | LumaSphere](https://lumasphere-6588c810433f.herokuapp.com/): Turn a photo or prompt into a 360° HDRI. Shape sun, sky, and indoor light, preview materials, and export a 32-bit EXR. Start with 3 free images.
- [HDRI Features & Lighting Science | LumaSphere](https://lumasphere-6588c810433f.herokuapp.com/about): Explore LumaSphere’s HDRI tools: spherical projection, linear light, exposure, focused light sources, material previews, and 32-bit OpenEXR export.
- [HDRI Generator Pricing & Monthly Plans | LumaSphere](https://lumasphere-6588c810433f.herokuapp.com/pricing): Start with 3 free HDRI images. Compare LumaSphere’s Starter, Creator, and Studio monthly plans, with lighting controls and 32-bit EXR exports included.