PCB Component Geometry#

Overview#

This capability defines the geometric and appearance ground truth carried on every placed PCB component and on its pins and meshes. It realizes the Component Geometry (CG) codes of the PCBA to USD Input Contract 1.0.2 (section 7 components, 8 component attributes, 9 mesh roles and material class, 10 pins): the data a board-asset author must supply so an AOI synthetic-data pipeline can place a component correctly, enumerate its contacts, reason about its height and orientation, and inject appearance / orientation / polarity defects against a known-good reference.

It covers five families of ground truth:

  • Placement — board side, nominal board-local position, and rotation about the board normal (pcba:component:side, …:nominalPosMm, …:nominalRotationDeg), plus the anchor convention (pcba:component:anchor, …:bodyCentroidLocal, pcba:mesh:originOffset on the body mesh) that makes placement deterministic when the mesh origin sits off the body.

  • Body dimensions — component height (heightMm); a body-mesh extent is recommended so world bounds and geometric cross-checks are computable.

  • Pins — pin count, pin pitch, and per-pin contact data (pcba:pin:number unique within the part, …:solderable as the per-pin solder authority, optional …:crossSection, …:terminalType, …:designator), plus the actual pin-1 position for orientation-sensitive parts. Each body, lead, and marking is its own prim; a merged lump cannot be defected or associated. Boards do not have pins: a board site names a pin with pcba:board:componentPinNumber.

  • Markings & polarity — polarity type and visible markings; when a part carries a pin-1 or polarity marker it is standalone geometry (pcba:mesh:role = pkg_marking), never baked into a texture.

  • Appearance & material — nominal (representative, not photoreal) body colour, finish, and material class on the component, and pcba:mesh:matClass authored on pkg_* / fixture_* meshes (derived from the role on board_*).

Real geometry is required for final training data; boxes standing in for parts are not acceptable, and a dimensionally correct outline extrusion is provisional only. Fiducial and mechanical placements carry a reduced set: side MUST, pose and appearance SHOULD, pin and identity fields Not Applicable.

Requirements#

Code

Requirement

Summary

CG.001

Placement

side on every placement; board-local nominal position (mm) and rotation about Z on electrical parts.

CG.002

Anchor & Geometry Reference

Declared anchor; bodyCentroidLocal on the part and originOffset on the body mesh give deterministic placement when the mesh origin is off-body.

CG.003

Body Height

heightMm > 0 (Z extent); a body-mesh extent is recommended.

CG.005

Pin Count

pcba:component:pinCount equals the number of pin prims.

CG.006

Pin Pitch

CONDITIONAL: contact spacing in mm when meaningful; omitted for 2-terminal passives.

CG.007

Pin Geometry

Per-pin number (unique within the part) and solderable (bool); crossSection, terminalType, designator optional.

CG.008

Pin-1 Position

CONDITIONAL: actual pin-1 offset from the anchor for keyed / orientation-sensitive parts.

CG.009

Polarity

CONDITIONAL: polarity type for polarized parts; an existing marker is standalone pkg_marking geometry.

CG.010

Markings

CONDITIONAL: visible marking text for OCR / wrong-part ground truth.

CG.011

Nominal Appearance

Representative body colour, finish, and material class on the component.

CG.012

Per-Surface Material

matClass authored on pkg_* / fixture_* meshes; derived from the role on board_*.

CG.018

Press-Fit State

Press-fit joints still get barrels; solder-defect applicability is determined per pin by solderable. No executable rule.
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