# Scene Light Rig Comparison

> Compare four deterministic light rigs on the same 3D concept. Keep the camera, object colors and geometry fixed while comparing soft key, side, high-key and grazing light. Download a four-tile SVG contact sheet and an editable Renderloom scene, then refine lighting locally.

Part of usefulweb.app (https://usefulweb.app/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://renderloomlightrigs.usefulweb.app/ (interactive tool at https://renderloomlightrigs.usefulweb.app/tool)
- JSON API: POST https://renderloomlightrigs.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://renderloomlightrigs.usefulweb.app/api/v1/tool)
- OpenAPI: https://renderloomlightrigs.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://renderloomlightrigs.usefulweb.app/mcp - tool `renderloom_light_rigs`

## Inputs
- project (textarea): Renderloom scene, render recipe or Form Studio JSON
- width (number): Tile width (px)
- height (number): Tile height (px)
- samples (number): Samples per pixel

## Method
- Four renders keep geometry, camera, materials and sampling seed identical. Only light direction, elevation, softness and ambient light change.
- The shared local concept renderer uses orthographic rays, direct light, sampled soft shadows, short-range ambient occlusion and one metal reflection. It does not execute MoonRay or load external renderers.
- Each tile is 32–96 pixels per side and one or two samples. The complete comparison permits 65536 pixel samples. Colors are display sRGB; output is a compact raster represented by SVG rectangles.