Step 1: Project Settings

The basic parameters for a photogrammetric project are defined in the first step of the Project Wizard.

This is how the first Wizard step looks like :

Press the button 'Edit Settings…' on this wizard pane to start editing some basic parameters:

In this dialog the following project parameters need to be specified:

• Define a name for the project: you are obliged to enter a project name.
• Select wether the project is a project with vertical photography (parallel camera axes), or with terrestrial photography (oblique).
  Differences between the two types may be obvious, but the software also behaves differently.
  The next table defines the differences:

• Select a Camera (eventually via the Camera editor).
  • There is a combobox with available camera definitions.
    Select the appropriate camera for your project.
    
  • If there is no appropriate camera available in the combobox, you need to define a new camera.
    Using the 'Add/Edit Camera' button next to the 'select camera' combobox to start the Camera Settings.

• Introduce the overlap percentage of the photographs.
  The default value is 60%.
• Introduce the overlap percentage that exists between strips.
  The default value is 20%.
• Introduce the minimum number of tiepoints in the model overlap.
  The default is 6 points.
• Introduce the minimum number of tiepoints per image, in strip overlap.
  The default is 2 points.
• Introduce the photoscale.
  The default value of 4000.
• Introduce the pixel size of the images, expressed in micron.
  The default value is 21 micron.
• Introduce the scale for viewing in the detail windows.
  The default value is 2000.
• Introduce an average ground height value expressed in terrain system units/1000.
  The default value is 0.03 km.
• Introduce the Projection System (CRS) where the project is situated in. Select a Projection using in meter as unit.
  The default Projection System is “Belgian Lambert 72”.
• Introduce the a-priori standard deviation in XY-direction expressed in terrain system units.
  The default value is 0.05 meter.
  This value is only used by the Bundle Block Adjustment module.
• Introduce the a-priori standard deviation in Z-direction expressed in terrain system units.
  The default value is 0.1 meter.
  This value is only used by the Bundle Block Adjustment module.
• Introduce the a-priori standard deviation of the observations expressed in mm. This is the accuracy of the measurements done in the image, normally a fraction of the pixelsize expressed in mm.
• Introduce the grid distance for DEM measurements in the X-direction expressed in terrain system units.
  The default value is 50 meter.
  This value is only used by DEM Stereo viewer.
• Introduce the grid distance for DEM measurements in the Y-direction expressed in terrain system units.
  The default value is 50 meter.
  This value is only used by the DEM Stereo Viewer.

When every field is entered correctly, press the OK button.

If some fields are not entered correctly you will be advised to do so.
e.g. When you press OK without entering the project title and without selection of a camera you will see the next dialog:

Pressing the OK button brings you back to the 'Edit Settings' dialog to let you correct the mentioned fields.

When all fields are finally accepted by pressing successfully the OK button on the Project Settings dialog, you will automatically continue with the next step in the wizard dialog.

To continue with the second step in the Project wizard goto Step 2 Exterior Orientation.

This dialog lets you:

1. Define a new camera or
2. Edit an existing camera in the camera database.

Once a camera is defined it is reusable in other Strabo Projects.

Here is the 'Camera Settings' dialog:

The 'Camera Settings' dialog shows on top a list of existing camera definitions.
You can view the respective parameters by selecting the camera of your choice.

The parameters are made visible using three tabs:

This pane is showing some main editable parameters:

1. The description may be any unique name you wish to describe the camera with.
2. The focal distance of the lens is found on the calibration certificate of the camera and expressed in mm.
3. 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:
  1. The exact pixelsize expresssed in micron.
  2. The correct coordinates of the corners of the image instead of the fiducial marks in the next tab 'Fiducial Marks' in this camera editor..
• Digital:
  In case of the Visionmap A3 camera the camera definition should look like the following display:

1. Photo width (expressed in 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 width multiplied by the pixel size.
2. Photo height (expressed in 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 height multiplied by the pixel size.
3. PBS X: the X coordinate of the point of best symmetry.
4. PBS Y: the Y coordinate of the point of best symmetry.
   These are the coordinates of the Point of Best Symmetry found on the calibration certificate and are expressed in mm.
   The PBS coordinate will be used in the calculation of the image coordinates.

,

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.
    

There are two ways of entering distortion values:

1) using tabular data for Radial Distortion
2) using paramteric formulas for Radial and Tangential Distortion

Or said in another way:

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

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:

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

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.

Select the distortion value you want to delete.

Press the 'Remove' button to delete the record from the list.

Change the Active type into “Parametric” and enter the parameters P1 and P2.

1. Select the tab “Tangential”
2. Select the 'Use tangential correction' toggle
3. enter the appropriate parameters

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

1. Press the 'Close' buttons to exit the 'Project Settings' and 'Camera Settings' dialogs.
2. Go to the next wizard step by pressing the button on the wizard dialog.