The Camera Settings Dialog

The Camera Settings Dialog

This dialog lets you (i) define a new camera or (ii) edit an existing camera in the camera database. Once a camera is defined it is reusable and available for other Strabo Projects. The 'Camera Settings' dialog shows on top a list of existing camera definitions. The existing list of “Predefined Camera's” is saved in the file “../ext/photogrammetry/cameraList.ini”. This set of camera definitions is shared with the UMP extension (Uav Mapping Planner) who needs also camera parameters to plan a flight mission. Use the “Import” and “Export” buttons for exporting camera definitions to other Strabo workstations. You can view the respective parameters by selecting the camera of your choice.

In case of Visionmap Imagery follow first this procedure: Preparation of Visionmap Imagery

The parameters are made visible using three tabs:

(1) General

This window shows some main editable parameters:

Description: The description may be any unique name you wish to describe the camera with.
Focal (mm): The focal distance of the lens is found on the calibration certificate of the camera and expressed in mm.
Type: there is choice between different camera types. This selection must be done for the sake of the automatic measurements of the fiducial marks. It defines the position and the form of the fiducial marks for the different type of cameras: RC20 - RC30 - Zeiss LMK - LC1030 - Zeiss RMK TOP 30 - Semi-Metric - Digital (In case of a Digital camera it is necessary to enter the following parameters correctly: (i) The exact pixelsize expresssed in micron and (ii) The correct coordinates of the corners of the image instead of the fiducial marks in the next tab 'Fiducial Marks' in this camera editor - Visionmap

Long Track (mm):
1. for scanned film: the approximate value expressed in mm is sufficiënt.
2. for digital images: enter the exact value equal to the number of pixels in the long track of the aerial flight (along the track) multiplied by the pixel size.
Cross Track (mm):
1. for scanned film: the approximate value expressed in mm is sufficiënt.
2. for digital images: enter the exact value equal to the number of pixels in the cross track of the aerial flight multiplied by the pixel size.

Pixel Size (micron): given in the calibration certificate of the camera and expressed in micron.

PP Longtrack (mm): the principal point of autocollimation along the flight direction.

PP Crosstrack (mm): the principal point of autocollimation across the flight direction.
These are the coordinates of the principal point found on the calibration certificate and are expressed in mm or pixels. In most cases these PP longtrack and crosstrack are expressed in PP X and PP Y whereas the X-axis is expressed according the orientation of the delivered images. When the images are rotated to fit in the flightplan, the PPX (and PPY) will be rotated as will be shown on the calibration report. Please read carefully the calibration report to interpret.
The PP coordinate will be used in the calculation of the image coordinates.

Use the “Modify” button to save all changes for General,
Fiducial Mark and Distortion parameters, in the camera database.

Use the “Remove” button to completely remove the selected camera from the camera database.

(2) Ficucial Marks

Here is an example of a classical camera having 8 fiducial marks. Each fiducial mark has its individual fiducial coordinates:

In this dialog you must enter the fiducial mark coordinates available from the camera calibration certificate. All values are expressed in mm. The positions of the fiducials are named after their position in the image with the instrument panel at the left side of the image.
In case of a digital camera : only the four corner positions have to be entered. These values reflect the exact size of the image.

(3) Distortions

There are two ways of entering distortion values:

using tabular data for Radial Distortion
using paramteric formulas for both Radial and Tangential Distortion

Or expressed in another way:

Radial distortion can be defined either in tabular form or parameteric.
Tangential distortion can only be defined parametric.

1a. Radial Distortion in Tabular form:

Fill in the distortion parameters for the camera lens according to the calibration certificate. These values are reflecting the actual light array position as measured, showing the distortion.

The different correction values are entered as follows:

be sure to have selected the correct camera in the top list.
enter the radius expressed in mm.
enter the corresponding distortion expressed in micron.
press the 'Add' button to add this new distortion value.
repeat steps 2 and 3 for each distortion correction available in the calibration certificate.
press the 'Close' button to end the editing or the creation of a camera.

Changing the distortion values: By selection a distortion record in the list, the corresponding values are entered in the Radius and Distortion fields,ready to be edited. After updating the value: press the 'Modify' button to modify the distortion list.
Removing a distortion value: Select the distortion value you want to delete. Press the 'Remove' button to delete the record from the list.

1b. Radial Distortion in Parametric form:

Change the Active type into “Parametric” and enter the parameters K1 and K2.

2. Tangential Distortion in Parametric form:

Select the tab “Tangential”
Select the 'Use tangential correction' toggle
enter the appropriate parameters P1 and P2

Extra: The parametric formulas

the  following parametric formulas (D. Brown) are used:
    dx = x(K1.r^2 + K2.r^4) + P1(r^2 + 2.x^2) + 2.P2.x.y
    dy = y(K1.r^2 + K2.r^4) + P2(r^2 + 2.y^2) + 2.P1.x.y

Table of Contents

The Camera Settings Dialog