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. In the Slate Material Editor create a CoronaBitmap (Maps > Corona), load the .exr or .hdr file and set its Mapping rollout to Environment mode: Spherical, which matches the equirectangular HDRI Hub files.
3. Drag the CoronaBitmap onto the Environment Map slot as an Instance, replacing the default CoronaSky. Alternatively set Render Setup > Scene > Scene Environment to Single map and load the CoronaBitmap there; Corona then ignores the 3ds Max slot, with no quality difference.
4. Rotate the map with the CoronaBitmap's Rotation value in degrees, or with U Offset, where 0.25 equals 90 degrees, 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.

Try before you buy: the free HDRI samples need no account and carry the same licence as the paid files, so you can check the setup above with a real file before buying.

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 34 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.

For plate-based shots, see matching an HDRI with a backplate.

Frequently asked questions

How do I use an HDRI in Corona?

Load it in a CoronaBitmap set to Spherical environment mapping and put that map in the 3ds Max Environment Map slot, or in Corona's Scene Environment override as a single map.

CoronaSky or HDRI?

CoronaSky is a procedural sky model. A photographed HDRI replaces it when you need a real location, real clouds and matching reflections.

Do I need a Corona Sun as well?

Not with an unclipped sky, whose sun disc already casts a hard shadow. Add a Corona Sun only for overcast or sunless HDRIs, and turn it off otherwise to avoid a double key light.

How do I rotate the HDRI?

Use the Rotation value on the CoronaBitmap, or U Offset in steps of 0.25 for 90 degrees.

More background: which HDRI resolution you need and .hdr or .exr.