Volume distortion (or volumetric distortion) is not a familiar term to most photographers, but it’s what makes ultra-wide shots look distorted at the edges, and it can be fixed… by the right software.
Volumetric distortion
A special type of distortion correction once built into DxO Optics Pro but now built into the separate DxO ViewPoint application. It fixes the distortion usually seen with wideangle lenses where objects near the edge of the frame appear disproportionately wide – it’s most obvious with human figures.