Simple HDR cubemap to longlat(longitude latitude. or known as equirectangular) converter.

Requirements

• C++11 compiler

Coordinate definition.

• Y-up
• Right-handed
• Center is -z

Usage

Assume cubemap image is given by 6 images(6 faces).

$ ./cube2longlat px.exr nx.exr py.exr ny.exr pz.exr nz.exr 512 longlat.exr (phi_offset)

Optional phi_offset is used to add offset(by angle) to phi to rotate X and Z faces.

Supported input image format

• RGBM(Filament's RGBM encoding. Multiplier is 16, and gamma corrected) Implemented but not tested.
• x EXR

Supported output image format

• RGBM(Filament's RGBM encoding. Multiplier is 16, and gamma corrected) Implemented but not tested.
• x EXR
• x RGBE

Note

When you create cubemap using Filament's cmgen https://github.com/google/filament/tree/master/tools/cmgen , its generated cubemap images are mirrored by X direction. Use --mirror when invoking cmgen if required.

TODO

• Single cubemap image(cross layout)
• Better antialiasing
• theta offset
• Mirroring.