Tuesday, 18 January 2011

HDRI light probe environment light test in Nuke

LDR still at eV 0
I shot an oversized christmas bauble from each side of my room using Magic Lantern on my 550d to bracket the exposures at -5, -2.5, 0, +2.5 and +5eV. The large exposure steps did introduce some banding when converted to HDRI.  Also, taking the stills with no tripod and not measuring distances resulted in shallow focus and the need to adjust the input rotation in the spherical transform when matching one lightprobe angle to the other in Nuke.  I also realise now that if I took the second set of exposures at a 90° angle form the first rather than 180° then I could have removed myself from the final image.

Each set of exposures were then converted to HDRI in Photoshop and saved as a 32bit float exr.

Two light probes converted to a single latlong HDRI

I then converted the light probes to lat long map using Nuke's spherical transform node. Once these were stitched together I exported my final lat long and set up a simple 3D scene using an environment light and a specular shader on the geometry.

3D comp with latlong HDRI driving envoronment light to illuminate geometry