September 2026 brought two open-source releases that matter to drone mappers: WebODM 3.3.0 and COLMAP 4.2.0. WebODM’s biggest change is Gaussian splat support, and COLMAP 4.2.0 was superseded by 4.2.1 four weeks later. This recap follows the August WebODM 3.2.8 and ODM 3.6.2 roundup and is compiled entirely from the GitHub release notes, pull requests, and official docs — nothing here comes from hands-on testing.
WebODM 3.3.0: Splats, Grid Shifts, and a 3D Selector
WebODM 3.3.0 (github.com/WebODM/WebODM, published 2026-09-05 18:17 UTC) lists nine pull requests. Four change what you see or get.
Gaussian splat support (PR #2017). The PR adds four things: downloading training data for Gaussian splats, uploading splat files, automatic tiling of those files into the .RAD format, and displaying splats in the 3D model view where you can “make measurements, use the standard Potree tools.” WebODM does not train the splat. The official docs spell out the loop: process an RGB dataset, download the training .zip from the task’s Splats menu, train it in external software such as OpenSplat or Brush, upload the result. The docs also carry a warning every mapping pilot should read first: “A nadir-only flight, usually yields very poor results.” The Gaussian splatting primer covers why.
Grid shift support and migration (PR #2012, #2016). A grid shift file is a correction grid that PROJ — the coordinate transformation library underneath most GIS software — needs for datum transformations that a simple formula can’t model accurately. If your task’s coordinate reference system needs one and the file isn’t installed, PROJ can’t use its best available transformation and positions shift. Per the PR, WebODM “will now automatically download the appropriate grid files on-demand (if network connectivity is available),” and a database migration goes back through existing tasks, “retroactively downloading the missing grid files and updating the task’s data.” The migration code re-derives each affected task’s raster extents and adjusts its crop polygon. PR #2016 keeps the grids in sync across the webapp and worker containers. The coordinate systems guide explains why the datum step bites.
3D type selector (PR #2005). The 3D view gets “a selector for switching between point clouds and textured 3D models, similar to Map View.”
Bilinear resampling for orthophoto tiles (PR #2013). The tiler now displays orthophoto tiles with bilinear resampling. The maintainer’s own note: “Looks better, at the cost of ~30-40% slower rendering (on my machine at least).”
| WebODM 3.3.0 change | PR | What it means |
|---|---|---|
| Gaussian splat training-data export, upload, viewing | #2017 | Splats sit alongside point clouds and meshes; training stays external |
| Grid shift auto-download + task migration | #2012 | Missing PROJ grids fetched on demand; older tasks corrected |
| Grid sync across containers | #2016 | Workers and webapp share grids; restored on restart |
| 3D type selector, faster Potree menus | #2005 | Switch point cloud / textured model in one view |
| Bilinear tile resampling | #2013 | Smoother orthophoto display, slower tile rendering |
shlex replaces removed pipes module | #2002 | Unblocks Python 3.13 and newer |
pdal.bat lookup; subprocess quoting, Electron CSS | #2019, #2020 | Windows and desktop-app fixes |
Upgrade notes. Run the upgrade with internet access. The grid migration is best-effort: it logs a warning and skips any task whose grid file it can’t download, so an offline upgrade leaves those tasks’ stored extents and crop polygons uncorrected. No newer WebODM release exists as of October 1, 2026. Full list: the v3.3.0 release notes.
COLMAP 4.2.0: The Global Mapper Stops Throwing Data Away
COLMAP is the structure-from-motion and multi-view stereo package many Gaussian splatting and NeRF pipelines use to solve camera positions. It is not part of the WebODM stack. The 4.2.0 GitHub release was published 2026-09-01 05:44 UTC; the project’s CHANGELOG dates it 08/31/2026.
Multi-component global mapping (PR #4589) is the headline. Before 4.2.0, the global mapper kept only the largest connected group of images and discarded the rest. The release notes: “Disconnected view-graph components are reconstructed independently and returned as separate models,” including components that only separate after outlier rotations are filtered. A site flown as two blocks with no matches between them now yields two models instead of one. The PR author’s benchmark across the 13 IMC2025 scenes reports registered images rising from 634 to 1,544 of 1,823. No drone-survey benchmark accompanies the PR.
This is also a breaking change. The global mapper “may therefore return multiple models for disconnected datasets.” Any script that assumes one output model needs a check. To restore the old behavior, set GlobalMapper.multiple_models to false.
The rest of the release, filtered for mapping relevance:
| COLMAP 4.2.0 change | Release-note detail | Who cares |
|---|---|---|
| Multi-component global mapper (#4589) | On by default; GlobalMapper.min_model_size drops small models | Anyone scripting global_mapper |
| Analytical reprojection Jacobians | ”approximately 1.2—1.55x faster incremental mapping for common pinhole and OpenCV camera configurations” | Anyone running incremental mapping with pinhole or OpenCV camera models |
ROCm/HIP for patch_match_stereo | Dense reconstruction on supported AMD GPUs; CUDA and HIP builds are mutually exclusive | AMD GPU owners (HIP_ENABLED build option) |
| Faster image warping | ”reported 4—7x improvements in common undistortion cases” | Anyone undistorting images |
| Spatial matching fix | Fixed for “missing pose priors and large projected coordinates” | GPS-tagged drone imagery |
| Graceful shutdown | First SIGINT or SIGTERM “preserves usable intermediate results” | Long unattended runs |
hierarchical_mapper option rename | Four options now prefixed HierarchicalMapper. | Existing scripts break |
Skip 4.2.0 and install 4.2.1. COLMAP 4.2.1, published 2026-09-29, restores “legacy bundle-adjustment behavior in the global mapper, fixing a regression introduced in 4.2.0.” It also fixes a hash-map backend problem that “made same-source builds ABI-incompatible and could corrupt memory,” and a Delaunay meshing loop that never terminated when a 3D point coincided with a camera center. Full list: the 4.2.0 release notes.
Also in the Window: ODX, NodeODM, QGIS
Three smaller releases landed in the same month. Which of the first two applies depends on which side of the ODM/ODX fork you run.
| Release | Published | Notable |
|---|---|---|
| ODX 3.8.3 | 2026-09-04 | WebODM’s engine. build-overviews removed “in favor of cog”; MicaSense RedEdge-P calibration fix; GSD estimated “from bottom 10 percentile instead of average” |
| NodeODM 3.6.2 | 2026-09-24 | First tagged release since v2.2.3; version now matches the ODM release it wraps; “GPU SIFT works”; Intel image tag renamed from gpu.intel to gpu-intel |
| QGIS 4.2.3 | 2026-09-25 | Point release, published alongside 3.44.15; the GitHub release carries a commit comparison link and no written notes |
If you run the OpenDroneMap-side stack on a GPU, read the NodeODM notes: the :gpu image published in October 2025 “was missing a CUDA library, so --feature-type sift silently ran on the CPU.” ODM itself had no release in the window — 3.6.2 from August remains current.
Bottom line: upgrade to WebODM 3.3.0 if you work in a coordinate system that needs datum grids or want splats next to your point clouds, and do it online. On COLMAP, go straight to 4.2.1 and check any script that expects a single model from the global mapper. If you run NodeODM with a GPU, pull 3.6.2, and if you use the Intel image, switch the tag from gpu.intel to gpu-intel.