A collection of volume renders and their scenes for pbrt-v4.
To render these you need to use a recent version of pbrt-v4 (specifically https://github.com/mmp/pbrt-v4/tree/06cdbec or newer).
pbrt --outfile ./ground_explosion/ground_explosion_aces.exr ./ground_explosion/ground_explosion.pbrt
imgtool convert --outfile ./scenes/images/ground_explosion_filmic.png --colorspace srgb --aces-filmic ./ground_explosion/ground_explosion_aces.exr
pbrt --outfile ./ground_explosion/ground_explosion_alt_aces.exr ./ground_explosion/ground_explosion_alt.pbrt
imgtool convert --outfile ./scenes/images/ground_explosion_alt_filmic.png --colorspace srgb --aces-filmic ./ground_explosion/ground_explosion_alt_aces.exr
pbrt --outfile ./aerial_explosion/aerial_explosion_aces.exr ./aerial_explosion/aerial_explosion.pbrt
imgtool convert --outfile ./scenes/images/aerial_explosion_filmic.png --colorspace srgb --aces-filmic ./aerial_explosion/aerial_explosion_aces.exr
pbrt --outfile ./matchbulb/matchbulb.exr ./matchbulb/matchbulb.pbrt
imgtool convert --outfile ./scenes/images/matchbulb_filmic.png --colorspace srgb --aces-filmic ./matchbulb/matchbulb.exr
pbrt --outfile ./anemone/anemone.exr ./anemone/anemone.pbrt
imgtool convert --outfile ./scenes/images/anemone_tonemap.png --colorspace srgb --tonemap ./anemone/anemone.exr
pbrt --outfile ./rainbow_box/rainbow_box.exr ./rainbow_box/rainbow_box.pbrt
imgtool convert --outfile ./scenes/images/rainbow_box_tonemap.png --colorspace srgb --tonemap ./rainbow_box/rainbow_box.exr
pbrt --outfile ./teapot_cloud/teapot_cloud_aces.exr ./teapot_cloud/teapot_cloud.pbrt
imgtool convert --outfile ./scenes/images/teapot_cloud_filmic.png --colorspace srgb --aces-filmic ./teapot_cloud/teapot_cloud_aces.exr