HDRI environment maps for Corona Renderer

Load an HDRI in Corona Renderer 15

1. Open Environment and Effects by pressing 8 or through the Rendering menu.
2. Swap the default CoronaSky map for a bitmap environment map and load the HDRI file.
3. In the Slate Material Editor, drag a CoronaBitmap onto the map slot instead if you need finer control, and set its Mapping rollout to Spherical, which matches most equirectangular HDRIs.
4. Rotate the map horizontally in its coordinates to align the sun and reflections with the scene.
5. Adjust exposure with a Corona Color Correct map on the bitmap rather than changing scene exposure globally; lowering gamma sharpens the lighting, raising it softens it.
6. Override scene materials with a neutral grey (except glazing) while checking the lighting, then restore materials before final render.

Corona reads standard .hdr and .exr equirectangular panoramas through CoronaBitmap or the standard 3ds Max bitmap environment map.

Which resolution

Corona's documentation does not publish a fixed pixel cap for environment maps. For lighting and reflections only, 4096x2048 to 8192x4096 is enough. For an environment visible directly in reflective surfaces or through glazing, use 16000x8000 to 20000x10000; Corona is an offline path tracer rather than a real-time engine, so the full 20000x10000 files are practical for final renders, not just previews.

Sun and shadows

Use one of HDRI Hub's 52 unclipped skies so the sun disc stays intact in the environment map and Corona resolves a sharp shadow edge from it. With the HDRI driving lighting through the environment slot, no separate Corona Sun object is required unless the HDRI itself lacks a visible sun.