> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cadd/dimensionline-cadd.md).

# Linear / Aligned Dimension

A **Linear / Aligned Dimension** measures and labels the distance between two points. The value updates automatically when the model geometry changes, so dimensions on a pier section stay correct as the pier resizes, span lengths change, or bearing offsets are revised.

Three dimensioning directions:

* **Horizontal** — measures the horizontal projection of the distance (typical for plan-view widths and elevation-view spans).
* **Vertical** — measures the vertical projection (typical for heights, depths, profile elevations).
* **Aligned** — measures the true distance along the line connecting the two points (typical for skewed dimensions and slope lengths).

## Pick points

Pick the first point, then the second, then a leader position offset from the dimensioned line. The dimension's value is the distance between the two points.

For section drawings, snap to corners, midpoints, or centers of the cut shapes (piers, footings, deck edges, bearings). For plan drawings, snap to pile centers, pier corners, abutment faces.

## Text and units

**Label:** Override text. Leave blank to use the auto-computed value (the default).

**Prefix:** Text shown before the value (e.g., `~` for approximate, `±` for tolerance).

**Suffix:** Text shown after the value (e.g., a unit symbol if not using auto-units).

**Unit Style:** How the value is formatted. Fractional (`6'-3 1/4"`), Decimal with symbol (`6.27'`), or Decimal with name (`6.27 ft`).

**Length Unit:** Override the project's length unit. Default uses the project's preferred unit. Set to a specific unit (in, ft, yd, mm, cm, m, km) to show one dimension differently from the rest.

**Precision:** Number of decimal places (or fractional precision for fractional unit style).

## Direction and placement

**Aligned:** When yes, the dimension follows the line between the two points (true distance). When no, the dimension is constrained to a horizontal or vertical projection per the Axis setting.

**Axis:** For non-aligned dimensions, sets the projection direction: Horizontal, Vertical, or Auto (picks based on the leader location).

**Text Fit:** What to do when the value's text doesn't fit between the two extension lines. Shrink (auto-shrink the text), Move Outside (place text outside the lines), or Always Outside (always place outside).

**Flip Text:** Mirror the text to read from the other side.

**Offset X / Offset Y:** Fine-tune the leader's position relative to the dimensioned line.

## Typography

**Text Height:** Text size in real units (e.g. 0.1 m or 0.3 ft for typical bridge sheet text at 1"=10' scale).

**Font Family:** Font face. Default a standard sans-serif font.

**Font Weight:** Bold or normal.

**Font Style:** Italic or normal.

## Notes

Dimensions live on a Level like any other shape — assign to a "Dimensions" level so all dimensions on a sheet pick up consistent styling.

When the underlying geometry changes (a pier widens, a span lengthens), the dimension value updates automatically. If a dimension's leader becomes badly placed after a geometry change, drag the leader handle to a better location — the value follows the geometry.


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