# Orthographic Registration

> Register front, side, back, and top orthographic reference views into a shared Blender coordinate contract. Use when a 3D model must match multi-view wireframes/templates, when side/back/top silhouettes are off, or before adding depth to a front-locked contour model.

- Skill: `roble3/orthographic-registration` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add roble3/orthographic-registration`
- Raw SKILL.md: https://api.skillmd.com/api/skills/roble3/orthographic-registration/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: roble3 (https://skillmd.com/u/roble3)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/roble3/orthographic-registration

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# Orthographic Registration

This skill prevents the common failure where the front view looks plausible but the side/back/top views are wrong.

## Coordinate contract

- Front view defines `X/Z` silhouette.
- Side view defines `Y/Z` depth envelope.
- Top view defines `X/Y` spread.
- Back view defines rear silhouette/material only; it must not rewrite the front silhouette.

## Workflow

1. Run `scripts/register_views.py` on the available view images.
2. Create orthographic reference planes/image empties with a single shared scale.
3. Align centerline and bbox centers before modeling.
4. Lock front X/Z boundary vertices.
5. Add Y depth from side/top envelopes using modifiers/displacement or vertex groups.
6. Validate all four cameras before export.

## Failure policy

If views disagree, front brand read wins. Document the conflict in `registration_report.json`.


## Front-plane rotation rule

In this Blender coordinate convention, the front camera looks along the Y axis and the reference silhouette lives in the X/Z plane. Therefore 2D rotations inside the front view are rotations around the **Y axis**, not around Z. Use `rotation_euler = (0, angle, 0)` for 2D component orientation in the front projection. Z rotation spins objects into/out of screen-space incorrectly for X/Z-plane meshes.

## Sources distilled

- Blender Image Empty/reference image controls for orthographic blueprints.
- OpenCV homography/alignment and geometric transforms for view registration.