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--- |
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license: cc-by-nc-4.0 |
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pretty_name: Mosaic Prague REALMAP Demo |
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size_categories: |
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- 1K<n<10K |
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tags: |
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- image |
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- fisheye |
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- sfm |
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- colmap |
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- geospatial |
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- gaussian-splats |
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- multicamera-rig |
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- mosaicX |
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--- |
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# Dataset description |
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Mosaic REALMAP Demo dataset with 9114 images collected with panoramic camera with global shutter sensors. You can find more about full dataset in this article: [Mosaic Prague REALMAP](https://www.mosaic51.com/featured/mosaic-realmap-explore-prague-in-unprecedented-detail-with-1-26-million-images/) Each image has its position written in EXIF metadata populated from IMU device paired with the camera. |
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Images from each sensor are electrically syncronized up to several nanoseconds and the whole device can be considered as a multicamera rig. Additional camera information, including .gpx track is provided. |
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Camera calibration is provided in COLMAP compatible format. |
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# Dataset |
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All extracted data is anonymized to comply with GDRP requirements. Faces and car plates are blurred and blurring masks are provided also. |
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Each image has its positional and time EXIF metadata build from frame_times.csv and route.gpx (alternatively, just route_frame_sycned.gpx can be used). Tools like COLMAP recognize this data and it may save some time for matching these images. |
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## DEMO_full_data |
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The folder contains original images from each camera sensor extracted from video stream it writes. 8-bit images, with fisheye lenses. Be careful using this data with tools which do not support fisheye type of distortion like Reality Capture. For such applications undistorted data is prefered. |
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It contains calibration in colmap format inside **calib_colmap.txt** which is compatible with cameras.txt output from COLMAP. |
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### COLMAP |
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#### Project |
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Import reel folder **reel_0017_20240117-094718** with cam0, cam1, ..., cam5 sub-folders inside. Select new database. |
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#### Feature extractor |
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Use "shared per sub-folder" option. Use OPENCV_FISHEYE model, but parameters can be modified later. With this option turned on images in each camN folder will share intrinstics and distortion parameters as they should. As a _mask_path_ select **reel_0017_20240117-094718_masks** folder. |
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After features have beend extracted, open database and modify camera parameters in the database using **calib_colmap.txt** file. |
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#### Feature matching |
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Exhausive matching may take significant amout of time. To avoid that use combination of sequential, spatial, vocabulary and transitive matching (or just run them in this order). |
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#### Reconstruction |
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It may help to switch off optimization of camera focal length, distortion parameters and principal point (principal point refinement is switch off by default) to speed up reconstruction a bit. |
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#### Post reconstruction step |
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Using COLMAP's CLI run rig_bundler_adjuster subcommand to enforce camera rig constrains. |
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#### Small colmap project |
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In folder **DEMO_small_subset_and_colmap_prj** there is a small COLMAP project example, including .db, project.ini and exported model. It also includes depth map project with extracted dense point cloud. |
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This may be useful if you wander how images should be loaded and db organized and matched. |
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## DEMO_full_data_undistorted |
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The same as DEMO_full_data except that images and masks are unfisheyed and undistorted. A simple distortion model can be applied to them, see **calib_colmap_undistorted.txt** file for their parameters. |
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### Reality Capture |
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For reality capture you can initialize all cameras as the same image group so they share the same distortion and intrinsics. Focal length can be initilized from values in **calib_reality_capture.txt** |
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# TODO |
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* Explain calibration format, share full .json calibration and visualization script |
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* Provide imu2camera calibration, provided poses for all images |
