Scanned-film camera

You can enter camera-calibration either automatically or manually.

With the available Import command, you can import an XML file of camera-calibration information, thereby automatically entering all of the information from the file you specify.

Note: The XML file you import must be in the correct format.

The manual process is to enter the specifics of the information to suit.

Camera calibration for a scanned-film camera has two modes:

FL & PPO: focal length (FL) and principal point offset (PPO)
FL, PPA & PPS: focal length (FL), principal point of autocollimation (PPA), and principal point of symmetry (PPS)

The PPO is defined as:

PPA - PPS

Note: You can obtain the PPA and PPS values from the camera-calibration report.

Using a grid file
If necessary, you can use a grid file to correct for distortion. A grid file is a self-calibration grid created with BINGO. The file contains, in addition to other parameters created after bundle adjustment, all distortions in image and ground space, such as lens distortion, Earth curvature, atmospheric correction, and others. The supported format of the grid file is Z/I (.dat).

To automatically enter camera-calibration information for a scanned-film camera

Click Text File....
In the File Selector window, select the file you want, and then click Open.

To manually enter camera-calibration information

Under Basic Camera Parameters:
1. In the Name box, enter the name of the camera that captured the images. The camera name is primarily used when exporting to BINGO.
2. Click the mode you want: FL & PPO or FL, PPA & PPS.
  If you selected FL & PPO, type the focal length, in millimeters, in the Focal length box, and then in the boxes beside Principal point offset (PPO), type the x and y offsets, in millimeters.
  
  - OR -
  
  If you selected FL, PPA & PPS, type the focal length, in millimeters, in the Focal length box, the x and y locations, in millimeters, in the boxes beside Principal point of autocollimation, and then in the boxes beside Principal point of symmetry, type the x and y locations, in millimeters.
3. If necessary, select the Apply self-calibration check box.
  Warning: Use self-calibration sparingly and only with a suitable math model.
  
  Notice that a +/- box appears beside the Focal length box (with FL & PPO selected) or the Principal point of autocollimation box (with FL, PPA & PPS selected). Type a number to represent the deviation limit you want to use. Entering a limit of 0 is the equivalent of free adjustment, which is also known as no constraints.
Under Distortion Correction, beside Method, select how you want to apply correction for distortion:
- To enter coefficients for radial-lens correction, click Radial lens and decentering, and then under Radial-Lens Coefficients, type an appropriate value in the boxes R0 through R7.
  If you have a table of distortion pairs, click Compute from Table, and then see Entering radial lens distortion from a table.
  
  Under Decentering Coefficients, in the boxes P1 through P4, type an appropriate value in each.
  Note: B1 and B2 are not used.
- To use a grid file, click Grid file, and then in the File box, type the path and name of the grid file or, to select a file, click Browse.
Under Fiducial Marks do the following:
- Beside Position, click an option according to where the fiducial marks will be collected: Edge, Corner, or Edge and corner.
- In the X and Y boxes beside Top left through Bottom left, type the x and y coordinates, respectively, of the fiducial marks, in millimeters.
If you do not have calibrated fiducial coordinates, click Compute From Length, and then see Calculating the fiducial coordinates from measurements.
Under Other Parameters:
1. In the Image scale box, type the nominal scale.
2. To correct for atmospheric refraction, select the Apply atmospheric-refraction correction check box.
3. To correct for curvature of the Earth, select the Apply Earth-curvature correction check box, and then in the Earth radius box, type the Earth radius in meters.