COLMAP Tracking Importer C4D V1.3 — Readme

Need help?

• Found a bug or have a feature request? Please open an Issue using the Issues tab.
• For quick questions or suggestions, you can also email me: elderlan.design@gmail.com.
• When filing an issue, include: Cinema 4D version, Redshift version, OS, a short repro, and any console errors.

Tutorial

• Installing and using COLMAP on Windows: How to use COLMAP
• Installing COLMAP on macOS: https://gist.github.com/celestial-33/07438792a11964ee5f6f02847b6dbb03 and https://gist.github.com/celestial-33/a016465fd854d79a1b93458f167baa6a

Required Tools & Links

1️⃣ COLMAP (v3.12.3): Required for its libraries, which GLOMAP utilises.
👉 https://github.com/colmap/colmap/releases/tag/3.12.0

2️⃣ GLOMAP (v1.1.0): Faster reconstruction tool. Use the WINDOWS-NOCUDA version.
👉 https://github.com/colmap/glomap/releases/tag/v1.1.0

3️⃣ FFMPEG: Command-line tool for converting video into an image sequence.
👉 https://www.gyan.dev/ffmpeg/builds/

4️⃣ AutoTracker v1.4 Batch Script: Updated script designed to work with GLOMAP on Windows 11.
👉 https://gist.github.com/polyfjord/fc213bac33b7eaaef4a80f4b6d9e5823

Credits

Big thanks to @Polyfjord
YouTube: https://www.youtube.com/polyfjord

In his video, Polyfjord built upon the previous automated 3D tracking photogrammetry workflow by introducing GLOMAP instead of just COLMAP. He explains how to download and prepare the necessary tools to make this workflow 100% open source.

Where this Script Fits

Polyfjord’s workflow focuses on Blender. However, exporting the tracking from Blender often causes bugs, framerate mismatches, or axis orientation issues when moving into other 3D software.

This Python importer for Cinema 4D fills that gap by:

• Building a Redshift-compatible camera with correctly baked PSR and focal keyframes.
• Handling axis conversion automatically (COLMAP → Cinema 4D).
• Importing sparse point clouds and setting up Matrix objects.
• Creating a constrained duplicate camera for flexible workflows.
• Automatically configuring scene FPS, timeline ranges, and render resolution.

⚠️ Note: To visualise the point cloud in the Cinema 4D viewport, you must manually set the Matrix object Distribution to Vertex.

Free Tool & Acknowledgment

This tool is completely free. If you use it in your projects, acknowledging Elderlan Souza as the creator of the Cinema 4D importer is greatly appreciated (but not compulsory).

Looking forward to seeing what you’ll create using it! ✨

For bugs, suggestions, or any other queries, please feel free to contact me at:
📧 elderlan.design@gmail.com

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How to Use the Importer in Cinema 4D

1. Launch Cinema 4D.
2. Go to Extensions → Script Manager → File → Load Script… and load the Python script colmap_importer.py.
3. Run the script from the Script Manager or assign it to a shortcut/menu.

4. In the importer dialog:

   • Select your Scene Folder (the one containing the SPARSE folder and IMAGES).
   • Set Sensor Width (mm) (typically 36 mm for full-frame cameras).
   • Enter your video FPS.
   
   • Adjust Global Scale if needed (default: 100).
   • Optionally, check Import Sparse Point Cloud.

5. Click OK to import.

6. The script will automatically:

• Create a Redshift Camera with baked animation.
• Duplicate it and add a constraint for flexibility.
• Import the sparse point cloud.
• Set scene FPS, timeline, and render resolution.

8. ⚠️ Remember:

   • To see the point cloud in the viewport, set the Matrix object Distribution → Vertex manually.
   
   • To configure the camera background, do the following manually:
   
   • Set Background → Override on the RS Camera.
   • Select the first frame from the project’s IMAGES folder.
   • Change mode from Image to Animation.
   • Set Animation Mode to Simple.
   • Set Timing to Frame.
   • Press Detect Frames to load the sequence.
   
   • To adjust the ground plane alignment, move the GLoMap_Scene_Orient group.
   
   • The RS_GLoMap_Render_Camera uses a constraint to follow this transform.
   
   • If you need to export to other applications, you can bake the Render Camera’s final transform after alignment.

Known Bug: Resolution & Background Distortion

• The scene resolution from COLMAP/GLOMAP isn’t always applied correctly. This causes the background image on the RS Camera to look distorted.
• Fix: Open Render Settings → Output, and re-type the output width or height. This forces Cinema 4D to update the film aspect ratio and restores the correct background image proportions.

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Fixing the framerate mismatch in After Effects

If the video framerate is 23.98 or 29.97 FPS, you will likely experience a mismatch when compositing because Cinema 4D can’t export at these framerates.
To demonstrate the issue, we can composite the image sequence generated by GLOMAP with the original footage. The fix also works for 3D sequences rendered from Cinema 4D.

1. Launch After Effects.
2. Import the original footage into After Effects and create a new composition.

3. Import the rendered sequence from GLOMAP (or Cinema 4D).

4. Select the original footage, right-click, Interpret Footage → Remember Interpretation (or Ctrl+Alt+C on Windows, Cmd+Option+C on Mac).

5. Select the image sequence, right-click, Interpret Footage → Apply Interpretation (or Ctrl+Alt+V on Windows, Cmd+Option+V on Mac).

6. To visualise the frame mismatch, add the image sequence layer on top of the original image and change the mode to Difference.

7. You can now see where the pixels mismatch (inverted colour).

8. To fix it, stretch the duration by 0.01% for the image sequence. Right-click the layer, Time → Time Stretch.

9. Change the stretch factor to 100.01% and click OK.

10. If all the pixels match, the frame will turn black.

This method, using the GLOMAP image sequence, works to visualise the fix. It can be applied to any 3D sequence rendered from Cinema 4D, except for the Difference blend mode, which is used only to visualise the mismatch in this tutorial.

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Setup & Use: AutoTracker v1.4 (.bat)

Follow these steps, extracted from the video transcript, to configure and run the batch script on Windows (CPU-only, no CUDA required):

1. Create the project folders

   • Make a new folder, e.g. AUTOTRACKER V1.4.
   • Inside it, create these subfolders (exact names):
     • 01 GLOMAP
     • 02 VIDEOS
     • 03 FFMPEG
     • 04 SCENES
     • 05 SCRIPT

2. Download the tools

   • COLMAP v3.12.3 (use this version specifically).
   • GLOMAP v1.1.0 (WINDOWS-NOCUDA).
   • FFMPEG (release essentials build).
   • AutoTracker v1.4 batch script (save as .BAT, not .TXT).

3. Populate 01 GLOMAP with COLMAP + GLOMAP

   • Extract the COLMAP download and open its BIN/ folder. Select all files in BIN and drag them into 01 GLOMAP.
   • Extract the GLOMAP download, open its BIN/ folder, select all files, and drag them into 01 GLOMAP as well. When prompted, skip identical files.
   • From the root of the extracted COLMAP folder, copy the entire PLUGINS/ folder into 01 GLOMAP (so 01 GLOMAP/PLUGINS exists).
   • Result: 01 GLOMAP should now contain COLMAP.EXE, GLOMAP executables, many .DLL files, and a PLUGINS/ folder.

4. Place your footage

   • Put your source video file(s) into 02 VIDEOS.
   • (From the video: disabling in-camera stabilisation and using a 180° shutter—e.g., 1/60 at 30 fps—can help produce better motion blur for tracking.)

5. Unpack FFMPEG

   • Extract the FFMPEG archive and move its contents into 03 FFMPEG (you should see BIN/ and related files inside 03 FFMPEG).

6. Add the batch script

   • Save AUTOTRACKER 1.4.BAT into 05 SCRIPT.
   • Important: when downloading from the browser’s RAW view, some browsers append .TXT. Save as ALL FILES and make sure the filename ends with .BAT only.

7. Run the script

   • Double-click 05 SCRIPT/AUTOTRACKER 1.4.BAT.
   • The first Windows security prompt may appear; allow it to run.
   • The script will:
     • Use FFMPEG to extract frames from your video (CPU).
     • Run COLMAP feature extraction over the frames.
     • Run GLOMAP to reconstruct and produce a track.
   • For faster processing, you can work with 1080p footage instead of 4K.

8. Outputs

   • The script will populate your 04 SCENES folder with the reconstructed project files (per the referenced script’s defaults).

Troubleshooting (from the video)

• If the .BAT won’t run, confirm the extension isn’t .BAT.TXT and that SmartScreen isn’t blocking it.
• CUDA isn’t required here; the demonstrated workflow runs CPU-only and is still ~4× faster than the older COLMAP-only setup.

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License

This importer is released as free to use and modify.
Credit to Elderlan Souza is appreciated but not compulsory when used in projects.