`exportPointCloud` defaults: GUI vs Python CRS difference¶

Status: unverified
Applies to: Metashape Pro 2.x — and PhotoScan 1.x via the same default-coordinate-system behaviour (under the older exportPoints name)
Edition: Pro
Diátaxis: explanation
Confidence: high
Last reviewed: 2026-05-29

Confidence: high. The default-coordinate-system difference is forum-attested with permalink (Agisoft support, 2016) and the Python API signature is introspection-confirmed on Metashape 2.2 — the crs= parameter is optional but defaults to chunk-internal when omitted.

Problem¶

You export a tie-point cloud or dense point cloud via the GUI (File → Export → Export Points), and the resulting .las / .ply opens in QGIS or CloudCompare with the points placed at their georeferenced coordinates. You then re-run the same export via Python (chunk.exportPointCloud("/path/output.las")), and the resulting file places the points near the origin (0, 0, 0) — a different coordinate system entirely.

Same chunk, same project, two completely different output coordinate systems. This is not a bug — it's a default mismatch between the GUI and the Python API.

The default mismatch¶

Export route	Default CRS for points
GUI (`File → Export → Export Points`)	The chunk's CRS (`chunk.crs`) — i.e., georeferenced coordinates
Python (`chunk.exportPointCloud(path)` with no `crs=`)	Chunk-internal coordinates — i.e., a local right-handed metric frame near `(0, 0, 0)`

"From GUI you are exporting points in the geographic coordinates, while script export saves the coordinates in the internal coordinates." — Agisoft support, 2016-03-01, PhotoScan 1.2 (permalink)

Same chunk.exportPointCloud API exists in 1.x as exportPoints (renamed at the 2.0 transition). The default-coordinate behaviour is unchanged across both names.

When this matters¶

The default mismatch only causes problems when the chunk is referenced. Three operational cases:

Project state	GUI default →	Python default →	Mismatch?
Fully georeferenced (≥3 cameras or markers with reference data)	CRS coords	Chunk-internal	YES
Two cameras with reference (chunk NOT marked "referenced")	Chunk-internal	Chunk-internal	No
Markerless / un-georeferenced photo set	Chunk-internal	Chunk-internal	No
Markers with no reference data	Chunk-internal	Chunk-internal	No

The "≥3 references for the chunk to be considered referenced" threshold is important. If you have only 2 cameras with EXIF GPS data, Metashape does not treat the chunk as georeferenced even though the Reference pane shows coordinates. Both GUI and Python then use chunk-internal — no mismatch.

Solution: pass `crs=` explicitly¶

Demo verified: ✗ — pending Tier 3 reproduction on a real Metashape install.

import Metashape

chunk = Metashape.app.document.chunk

# Implicit (chunk-internal coords — usually NOT what you want)
chunk.exportPointCloud("/path/output_local.las")

# Explicit chunk CRS (matches GUI default)
chunk.exportPointCloud(
    "/path/output_geo.las",
    source_data=Metashape.DataSource.PointCloudData,
    crs=chunk.crs,
)

# Explicit different CRS (e.g., WGS84 lat/lon)
wgs84 = Metashape.CoordinateSystem("EPSG::4326")
chunk.exportPointCloud(
    "/path/output_wgs84.las",
    source_data=Metashape.DataSource.PointCloudData,
    crs=wgs84,
)

For tie-point export specifically (sparse / matched feature cloud), use:

Demo verified: ✗ — pending Tier 3 reproduction on a real Metashape install.

chunk.exportPointCloud(
    "/path/tie_points.las",
    source_data=Metashape.DataSource.TiePointsData,
    crs=chunk.crs,
)

The source_data= distinguishes which point set to export — omitting it defaults to the dense point cloud (PointCloudData).

Forcing chunk-internal export from the GUI¶

If you want chunk-internal coordinates from a referenced chunk, the GUI does not directly expose this — it always uses the chunk CRS for referenced chunks. To force chunk-internal:

"Clear the coordinate information in the Reference pane and also use Reset Transform option in the chunk context menu after right-clicking on its label in the Workspace pane." — Agisoft support, 2016-03-01, PhotoScan 1.2 (permalink)

This drops the chunk's reference frame entirely, making the chunk no longer "referenced" — at which point GUI and Python both export in chunk-internal coords. The downside is that re-georeferencing requires re-loading marker / camera reference data.

Caveats¶

chunk.crs is None for non-georeferenced projects. If you call chunk.exportPointCloud(path, crs=chunk.crs) on an un-georeferenced chunk, you pass None — which Metashape treats as "chunk-internal" (the same as omitting crs=). Defensive check:

out_crs = chunk.crs or Metashape.CoordinateSystem("EPSG::4326")
chunk.exportPointCloud(path, crs=out_crs)

Z-axis sign may flip between chunk-internal and the chunk CRS depending on the CRS's axis order. Most projected CRSes (UTM, State Plane) are right-handed with Z up; chunk-internal is also right-handed but has its origin near the project's centroid. Geographic CRSes (lat/lon) preserve handedness but the X/Y axes swap from "easting/northing" to "longitude/latitude."
The shift= parameter moves the export's origin by an arbitrary 3D offset — useful for downstream tools that don't handle large coordinate values (UTM coordinates can exceed the range of single-precision floats). Pass shift=Metashape.Vector([ E_origin, N_origin, 0]) to centre the output on a specific Easting/Northing.
Metashape.exportPoints (the 1.x name) was renamed to chunk.exportPointCloud at the 2.0 transition. Old scripts using exportPoints need updating; the parameter set is similar but point_class= was removed (use clip_to_boundary=
point_clouds= instead).

References¶

Metashape Pro User Manual (2.3), ch. 5 Export Point Cloud / Tie Points — describes the GUI dialog options.
Metashape Python API Reference (2.3.1): Chunk.exportPointCloud, parameter crs, Chunk.crs, CoordinateSystem, DataSource.PointCloudData, DataSource.TiePointsData.
Forum thread, Different point cloud from script export, 2016 — the canonical Q&A; default-coordinate-system difference identified by Agisoft support.

exportPointCloud defaults: GUI vs Python CRS difference¶