Mega Merge Mosaic

Features

• Photometric matching: a global photometric solve with robust per-overlap linear fits plus a per-panel gain/offset adjustment, per channel, absorbing panel background steps of 2× and more automatically.
• Seam blending: star-avoiding seams with hard star ownership, so every star (including its diffraction spikes) comes from exactly one panel and misregistration can't pinch or double it. The star-free background blends on a Laplacian-pyramid multiband base.
• Session workflow: analyze scans panels once into a session directory (reprojection, summaries, photometric solve), and blend streams the finished mosaic from that cached session, so re-blending or checking a report doesn't repeat the analysis.
• 32-bit FITS output: the blend is a 32-bit float FITS mosaic with planar channels, and the astrometric solution is carried into the output.
• XISF input: accepts registered full-canvas panels from MosaicByCoordinates, or raw plate-solved panel stacks, which are reprojected onto a fresh mosaic frame automatically.

CLI

Analyze the panels once into a session, then blend the mosaic from that session:

mmm analyze panels/*.xisf --session mosaic.mmm-session
mmm blend --session mosaic.mmm-session -o mosaic.fits

Downloads: GitHub releases.
Comprehensive CLI documentation is available on GitHub.

PixInsight Integration

Mega Merge Mosaic ships as MegaMergeMosaic, a process in the Mosaic category, driving the same analyze/blend pipeline as the CLI from inside PixInsight. Documentation is included with the module, available through PixInsight's process documentation viewer.

Requires PixInsight 1.9.5 or later. MegaMergeMosaic 1.5.0 reads the astrometric solution format introduced by PixInsight 1.9.5 (XISF 1.0 revision 1), and files solved with 1.9.4 and earlier remain readable. If you are still on PixInsight 1.9.0 to 1.9.4, the same repository keeps offering MegaMergeMosaic 1.4.2 instead; that version is no longer updated, so upgrade PixInsight to receive new releases.

1. Open Resources → Updates → Manage Repositories.
2. Click Add, paste the repository URL:
   https://tools.astrometrical.com/pixinsight/ Copy
3. Accept, then run Resources → Updates → Check for Updates and apply.
4. Restart PixInsight; find MegaMergeMosaic under Process → Mosaic.

Beta channel

Testers can point PixInsight at a beta repository to receive pre-release builds ahead of the stable channel. Use it in place of the stable repository above, not alongside it; having both installed is not supported. Beta builds also require PixInsight 1.9.5 or later.

Beta builds are unpolished, so expect rough edges. Stick with the stable repository unless you're specifically testing.

Test data

A 12-panel mosaic of the Orion region is available for trying out Mega Merge Mosaic, provided as three datasets:

• Raw stacked panels with astrometric solutions.
• Raw stacked panels (2× drizzle) with astrometric solutions.
• Panels pre-aligned by PixInsight's MosaicByCoordinates, ready to blend without reprojection.

Download the datasets from Google Drive.

The data is licensed under CC BY 4.0. You're free to process and share it, including in tutorials and videos, as long as you credit Astrometrical and don't present the data as your own. A license file is included with each dataset.