render_volume_projection — 3D `render` op

• Data kinds: voxel → image2d

• Call: import fullseye as fs; fs.ledger.render_volume_projection(vol, azimuth=0.0, elevation=0.0, mode='xray', device='cpu') (to call the implementation directly, import match3d; match3d.render_volume_projection(vol, azimuth=0.0, elevation=0.0, mode='xray', device='cpu'); from the registry, ops3d.get("render_volume_projection"))

• GPU: this op has a GPU path (device="cuda")

Usage

Project a voxel volume to 2-D from an arbitrary viewpoint (mode = xray = attenuation integral / mip = maximum). For DRR (X-ray) and world-model observations.

Rotates the volume toward the view direction with grid_sample and projects along an axis. The arbitrary-viewpoint version of voxel_to_mips.

The rotation uses affine_grid (coordinate order x=W, y=H, z=D) about the volume centre: azimuth is about the H axis (mixing W and D), elevation about the W axis (mixing H and D), both in degrees, in the order Rx @ Ry. The rotated volume is collapsed along axis 0 (D), so the line of sight is the rotated D axis. mode="mip" takes the maximum, everything else is a sum ("xray" is not the Beer-Lambert exponential but a simple accumulation; for an attenuation image apply exp(−Σ) on the caller side). Returns (H, W) float32 numpy. Outside the volume is filled with 0, so when the rotation cuts off corners the sum drops (use a near-cubic volume and put the object at the centre). The mip with azimuth=elevation=0 has the same orientation as voxel_to_mips()[0].

Uses: synthesis of DRRs, generating 2-D templates for ncc_locate, an arbitrary-viewpoint version of match_mip_2d.

Background guides (the physics and conventions behind this op)

• blender_interop — Using Blender alongside — build the shape, measure it with fullseye (pitfalls: axes, units, ground truth)

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

Runnable examples (verified samples that actually call this op)

• ct_hand_radiograph — py -3.11 examples_3d/ct_hand_radiograph.py

Ops the type connects to (they accept `image2d` as input)

fuse_to_voxel · fit_poly_surface · eval_poly_surface · surface_form_error · background_flatten · polar_unwrap · fit_zernike · matcap_shade

Same category (`render`)

project_points · render_point_depth · render_shaded · ambient_occlusion · cast_shadow · phong_shade · matcap_shade · supersample_mesh

*Provenance: match3d.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

render_volume_projection — 3D render op