If you are looking at https://colmap.github.io/faq.html#reconstruct-sparse-dense-model-from-known-camera-poses
# Instructions - To reconstruct using your Cam Params
Between running the feature extractor and running a mapper you need to update the database with your camera params.
In Colmap Gui create a new project and run feat extraction. Then update the database with your camera params using database_update provide the images.txt cameras.txt and your database.db using these flag --images_file --cameras_file --database_path. Go back into the Gui run feature matching and then start reconstruction.
Run python database_update.py and provide the images.txt cameras.txt and your database.db using these flag --images_file --cameras_file --database_path
