A quick guide to the Calibration of any camera using ITwin Capture Modeler

Steps to Accomplish

Step 1. Camera Setup

1. Remove optical stabilization.
2. Disable photo auto-rotation.
3. If you are unfamiliar with the camera use <<Automatic>> mode
4. Fix the focal length.
5. Fix the image dimensions.

Changing the camera focal length (zoom+/-) and / or the image dimensions will result in a different calibration.

Step 2. Photo acquisition

1. Select a highly textured and geometrically complex scene.
2. Acquire photos at 360 deg around the subject.
3. Shoot photos holding the camera in different positions (horizontal / vertical). NB. this only applies if auto-rotation mode is disabled.

Step 3. Process your dataset in iTwin Capture Modeler

1. Create a new project and import your photos.
2. In the Photos tab under Photogroup, select the type of camera being used > Camera model type perspective / fisheye.
3. Submit an aerotriangulation. In the Aerotriangulation Definition Settings keep the settings set at default

Step 4. Store your camera calibration in the user database.

1. Go to the Photos tab of the Block and right click on the Photogroup. Click << add camera to database >>.
2. When processing another project using the same camera, the latest calibration will be used by default. If not, you can still browse to it from the camera database by selecting << get camera model from the database >>.

Step 5. Prevent the software from adjusting the parameters.

1. In specific cases, you may want to prevent the software from adjusting the camera parameters, i.e. If a calibration already exists or has already been imported from the database.
2. In the Aerotriangulation Definition Settings, under Optical parameters select the option "Lock all parameters".

        3. Click on Submit to complete the aerotriangulation.