gr_raytracer image gallery
Showcase
Pairs of renders that isolate individual GR effects with synthetic
textures. Each pair shares its camera exactly, so every difference between
the two images is purely the spin (a = 0.499, i.e. a/M = 0.998, vs a = 0).
Reproduce with images/create-showcase-images.sh (scene definitions in
scene-definitions/showcase-*.toml, disc bitmaps generated by
scripts/generate_showcase_textures.py).
Shadow shape (equatorial view)
Top, a = 0.499: the shadow flattens on the prograde side (the "D" shape) and shifts off-center. Bottom, a = 0: a centered circle.
Frame dragging (view down the spin axis)
Top, a = 0.499: the sky's radial spokes wind around the shadow, dragged by the hole's rotation. Bottom, a = 0: the same spokes stay ruler-straight to the photon ring.
3x zoom onto the shadow region, where the twist concentrates (it falls off roughly as 1/r^3, so the outer tiles are barely affected). Top, a = 0.499; bottom, a = 0.
Lensing image orders (ring-and-spoke disc)
Rings are coded by absolute Boyer-Lindquist radius (same color = same r in both images); dark spokes reveal azimuthal shear between the direct image, the lensed far side over the shadow, and the underside image below it. Top, a = 0.499: gas reaches the prograde ISCO at r = 0.62 and hugs the shadow. Bottom, a = 0: the ISCO at r = 3 keeps the inner edge far out.