Measurement Import and Export

TunnelCAD reads and writes per-section measurement data (line points) as ASCII text files, in addition to the LandXML round-trip described in LandXML Import and Export. These ASCII workflows are intended for exchanging survey data with total stations, scanners, and external analysis tools that produce simple delimited text.

Concepts

A measurement in this context is a 3D point that belongs to a specific cross-section’s line data. The import and export tools share the same column-mapping engine (the format profile system), which lets the same file shapes be read and written.

Three coordinate flavours are supported:

XYZ

World-coordinate points. The alignment engine reduces each point to its nearest section via offset-aware projection. This is the format produced by most field instruments.

Station / Offset / Z

Pre-projected points already expressed along the alignment. The station selects the section; the offset is signed (right-positive) and Z is the absolute elevation.

Station / Offset / dZ

Same as above, but Z is the difference from the alignment axis at that station rather than an absolute elevation. This matches TunnelCAD’s internal section-local convention.

Note

Section local coordinates inside TunnelCAD use dZ from the offset-axis point, not absolute Z. The Sta-Off-dZ flavour matches this internal representation; the other two are converted on the fly.

Format profiles

A format profile names a column layout (delimiter + column roles such as Name, X, Y, Z, Sta, Offset, DZ, Code, Ignore). 13 profiles ship out of the box:

  • CSV variants (5) – comma-delimited XYZ and station-based layouts. The default is Name,X,Y,Z.

  • Whitespace variants (7) – space- or tab-delimited equivalents.

  • LandXML – reads <CgPoints> from a LandXML file using the same column mapping abstraction.

Profiles can be renamed (with the active delimiter visible in the list) and reordered. Custom profiles are saved with the application settings.

Importing measurements

Open the workbench from File > Import Measurements….

Two-tab workflow

The dialog has two tabs that share the same target alignment and line-definition selection:

  1. ASCII – pick one or more text files, choose a profile, parse, then commit.

  2. LandXML – pick a LandXML file and commit its CgPoints.

Workflow

  1. Choose the line definition(s) the imported points should populate. Multi-select is supported – when multiple files are selected, each file binds to one line definition.

  2. Pick the format profile. The Auto-resolve toggle lets TunnelCAD guess from the file extension and column count; switch it off to lock a profile manually.

  3. Click Parse. The preview grid fills, the progress bar advances, and any rows that fail to bind to a section are flagged.

  4. Pick the commit policy:

    Replace

    Existing line data on the bound section is cleared once per (section, line-def) group, then replaced with the parsed points.

    Append

    Parsed points are appended to whatever the section already holds.

    Skip

    Sections that already have data for the chosen line def are left alone.

  5. Click Commit. The activity log records the import as a single project event. See Calendar / Activity Log.

Snap-to-nearest binding

For XYZ inputs the engine projects each point onto the alignment via MeasureOffset. Points are snapped to the nearest configured section, not interpolated – if your sections are sparse you will see clusters at each chosen station rather than a smooth curve.

Exporting measurements

Open the workbench from File > Export Measurements….

Dialog options

File / folder

Choose an output file. When multiple line definitions are selected the field is treated as a folder and each line is written to its own file (<basename>_<linename>.<ext>).

Profile

Pick from the ASCII profiles. The LandXML profile is hidden here – use File > Export LandXML… instead.

Line definitions

Checklist of line defs on the active alignment. Each selected entry produces one file.

Station range

Optional from / to limits.

Header

Optional first line containing the column names plus the line definition name.

Preview

Live preview memo showing what the first rows will look like with the chosen profile.

Notes

  • Bulges (arc tangent values) are not part of the cross-section .tun storage and are therefore not written.

  • The progress bar advances per section; the dialog auto-closes on success.

  • The activity log records the export as a single project event.

Round-trip

The export side writes files that the import side can read. A common workflow is to export current measurements, edit in a spreadsheet, then re-import with the Replace policy to overwrite the original data.