Fix inconsistent between the actual executed image reader option and the saved project.ini file

[xuchenghust]

In current AutomaticReconstructionController implementation, the cli args input are first parsed to construct the member variable options_ of AutomaticReconstructionController class.
Then the options_'s ImageReader part is assigned to ImageReaderOptions reader_options, which is a copy instead of a reference of *option_manager_.image_reader. Which means, user cli args input's ImageReader setting (e.g. single_camera, camera_model) are only passed to options_, and will not be synced to option_manager_.

Although the ImageReaderOptions setting reader_options is used to construct the SiftFeatureExtractor, the executed setting is exactly what the user needed. Because the project.ini writing only follows the option_manager_'s values, thus when user modify the default automatic_reconstructor settings (by passing --single_camera=1 or --camera_model="OpenCV"), inconsistency happens between the actual executed image reader option and the saved project.ini file.

This bug can be easily fixed by obtaining reader_options by reference instead of a value copy.

---

- Bug case (using single_camera=1)
Pre Fix:
command:

.\build\src\exe\colmap.exe automatic_reconstructor --workspace_path=data/pre_fix/images --image_path=data/pre_fix/images --single_camera=1

generated project.ini

log_to_stderr=false
random_seed=0
log_level=2
database_path=data/pre_fix/images\database.db
image_path=data/pre_fix/images
[ImageReader]
single_camera=false
single_camera_per_folder=false
single_camera_per_image=false
existing_camera_id=-1
default_focal_length_factor=1.2
mask_path=
camera_model=SIMPLE_RADIAL
camera_params=
camera_mask_path=
[SiftExtraction]
...

After Fix
command:

.\build\src\exe\colmap.exe automatic_reconstructor --workspace_path=data/fix/images --image_path=data/fix/images --single_camera=1
generated project.ini
log_to_stderr=false
random_seed=0
log_level=2
database_path=data/fix/images\database.db
image_path=data/fix/images
[ImageReader]
single_camera=true
single_camera_per_folder=false
single_camera_per_image=false
existing_camera_id=-1
default_focal_length_factor=1.2
mask_path=
camera_model=SIMPLE_RADIAL
camera_params=
camera_mask_path=
[SiftExtraction]
...

- Bug case (using --camera_model="OpenCV")
Pre Fix
command:

.\build\src\exe\colmap.exe automatic_reconstructor --workspace_path=data/pre_fix/images_01 --image_path=data/pre_fix/images_01 --camera_model=OPENCV

generated project.ini

log_to_stderr=false
random_seed=0
log_level=2
database_path=data/pre_fix/images_01\database.db
image_path=data/pre_fix/images_01
[ImageReader]
single_camera=false
single_camera_per_folder=false
single_camera_per_image=false
existing_camera_id=-1
default_focal_length_factor=1.2
mask_path=
camera_model=SIMPLE_RADIAL
camera_params=
camera_mask_path=
[SiftExtraction]
...

After Fix
command:

.\build\src\exe\colmap.exe automatic_reconstructor --workspace_path=data/fix/images_01 --image_path=data/fix/images_01 --camera_model=OPENCV

generated preject.ini

log_to_stderr=false
random_seed=0
log_level=2
database_path=data/fix/images_01\database.db
image_path=data/fix/images_01
[ImageReader]
single_camera=false
single_camera_per_folder=false
single_camera_per_image=false
existing_camera_id=-1
default_focal_length_factor=1.2
mask_path=
camera_model=OPENCV
camera_params=
camera_mask_path=
[SiftExtraction]
...

[ahojnnes]

LGTM, thanks.