bench-camera-scene-alignment

name	bench-camera-scene-alignment
description	Before debugging a gray/black bench frame, verify the camera Y-position matches scene geometry Y-level — a camera 20 units above ground looking horizontal sees nothing below the viewport, producing gray frames indistinguishable from rendering pipeline failures.
source	auto-skill
extracted_at	2026-06-16T02:10:00.000Z

Bench Camera-Scene Alignment Pitfall

When a custom bench produces solid gray or black frames with no visible geometry, check this FIRST before diving into render-pipeline debugging.

The trap

A camera positioned at (0, 25, 0) looking horizontally at (0, 25, -10) with FOV 60° has a vertical field of view of roughly ±5.7 units at 10m distance. If all scene geometry is placed at y=5 (the default for many bench scenes), the geometry is 20 units below the camera's sight-line — completely outside the viewport. The result is a solid gray/black frame indistinguishable from a rendering pipeline failure.

The check

1. Compare camera_y position to geometry_y position.
2. Verify the vertical offset is within distance * tan(fov_y/2).
3. Ensure the look_at point is at the same height as the geometry, not the camera.

Titan specifics

• The titan-render-bench default camera is at (0, 25, 35) looking at origin — it sees a ground plane at y=0 because the camera is above and angled downward (~45°).
• A center-facing camera at (0, 5, 0) looking at (0, 5, -10) sees geometry at y=5 because the look direction is horizontal at the same height.
• If the camera uses a different height than the cubes, the look-at must be adjusted to point at the cube height.