Using known camera positions
WIP (experimental feature, don´t expect it to work right away. Some tinkering is required.)
(matchFromKnownCameraPoses in the FeatureMatching node is not available in the 2019 release. )
In most of the cases using known camera positions is only useful for research. If you are looking for a way to improve accuracy: your own calculated camera poses are probably not precise enough. Using previously computed Meshroom sfm files will work though.
modifying existing cameras.sfm file
- Compute the default pipeline with a set of images to the SFM node.
- Open the SFM node folder
- Inspect the cameras.sfm file (you can compare it to the cameraInit.sfm to see what lines need to be added with your known camera positions.) Create a new cameras.sfm file with your known camera data in a new folder somewhere.
When creating your own sfm file, remove
`"featuresFolders":... and "matchesFolders": (leaving this in the sfm file messes up the paths).
[set "locked": "0" to "locked": "1" ]
Create a new cameras.sfm file with your known camera positions in a new folder somewhere. Rotation format Make sure your new sfm file uses the correct syntax and you did not miss any quotation marks (...).
- disconnect CameraInit and FeatureExtraction
- Input the new cameras.sfm in FeatureExtraction
- make sure the node shows advanced settings (click on ... in the upper right border of the node settings)
- in FeatureMatching you can now select "Match from known camera poses" (only in MR2020.x)
- in StructureFromMotion "Lock Scene previously reconstructed" and "Force Lock of all Intrinsic Camera Parameters"
-> https://github.com/alicevision/meshroom/issues/1240
#399, #740, #453, #475, #300, #787, #788, #747, #807, #721, #725, #1128
(Note: pose and rotation values may change from the 16+ digits after the decimal point)
Note: The creators of scAnt (an open-source platform for thecreation of 3D models of arthropods(and other small objects)) wrote their own script to create a sfm file with estimated poses. It can be used as reference: https://github.com/evo-biomech/scAnt/blob/master/scripts/estimate_camera_positions.py