Attaching IQPC Files

What is IQPC?

IQPC (IQsoft Point Cloud) is TunnelCAD’s native cached point cloud format. It stores point coordinates, colors, and a spatial octree index in a compact binary layout optimized for fast loading and spatial queries.

When you import a raw point cloud (LAS, E57, etc.), TunnelCAD automatically creates an IQPC cache file alongside the project. On subsequent sessions, the IQPC file is loaded directly instead of re-parsing the original format – typically an order of magnitude faster.

Attaching an existing IQPC file

To re-link a previously created IQPC file without re-importing raw data:

  • Menu: Point Cloud > Attach (.iqpc)…

A file dialog opens. Select the .iqpc file and it is loaded into the project immediately.

When to use Attach

  • Reopening a project – if the IQPC cache was moved or the automatic cache path no longer resolves, use Attach to point TunnelCAD at the correct file.

  • Sharing between projects – multiple tunnel projects can reference the same IQPC file. For example, if two tunnel alignments pass through the same scan area, both projects can attach the same cached cloud.

  • Working on a different machine – copy the IQPC file to the new machine and attach it rather than re-importing the original raw data (which may be very large or unavailable).

File management

Note

IQPC files can be large (comparable in size to the original point cloud). Keep them on a local or fast-access drive for best performance. Loading IQPC files over a network share may be noticeably slower.

  • IQPC files are independent of the raw source data. Once created, the original LAS/E57/PLY file is not needed for viewing or section extraction.

  • Deleting an IQPC file does not affect the project – you can always recreate it by re-importing the raw data.

  • The IQPC format includes the octree spatial index, so no additional indexing step is required after attaching.