Assigning the camera to a sequence

Once you have created a camera, you can assign it to a sequence. Click a sequence and in the Parameters Window, choose the camera that you want to assign to the sequence from the Camera drop-down list.

Notice that the enabled camera is shown in bold in all the tree views.

Setting up a camera

Click the camera to view its properties in the Parameters Window. Note that computed camera values are grayed out in the Parameters window if they do not correspond to the current camera.

Time Range

If needed, select a time range. Using a time range is needed when you want to tweak a parameter over a given time interval. For example, you know that the focal length between frames 20 and 30 is fixed.

The camera parameter window time range is synchronized with the time line: when you move to a new frame, it automatically switches to this frame. When you select an interval, it switches to “Use Selection” with this interval. You can also simply select “Global Time” to apply your changes to all the frames.

Camera type settings

1. Select the type of camera from the Type drop-down list. The drop-down list contains standard camera types. These provide you with default parameter values for the selected camera type.

   For example, selecting Type PAL gives you a camera with the principal point in the center of the image; a pixel aspect ratio of 1.06667, a focal length initialized at 50 mm and a non-linear distortion set to 0. If you set Type to User in the camera Parameters Window, you can define your own parameters for the camera.

   NoteThe camera Type reverts to User if you change any value. Since the default camera types feature an image size, the camera will revert automatically to User if your sequence or image has a different size.
   NoteAll the predefined camera types are stored in the Data > Camera Types subdirectory of your installation. Each camera is stored in a simple “.cam” ascii file. You can easily add/edit/remove those file to customized your camera database. Just look at one of these file, and you’ll see how to do it!
2. The Film Back shows the Height and Width of the film back, either in mm or inches (use the unit combo box at the top to switch). If you change the height or width, the pixel aspect ratio changes, accordingly.
3. If an anamorphic camera was used to shoot the footage, the Lens Squeeze Factor may be different from the default value of 1.0. If this is the case, change the value in the corresponding text field.
4. Three read only fields show the image resolution. Width, Height and Ratio giving the size of the loaded image. Ratio is the value of the Width divided by the Height.

Camera parameter types

There are five different camera parameter types as explained in the following table. When you create a new camera, by default the three intrinsic (or internal) camera parameters-- principal point, pixel aspect ratio, and non-linear distortion-- are of the type fixed. The focal length is of the type “constant initialized”.

#This option is only available for the focal length parameter

All these types are in fact a combination of two settings. One controls the way the parameters vary over time: is it constant or variable . The other one controls the way the computation starts: unknown , initialized , or fixed .

These two settings are easily set though simple push buttons in the camera parameters window.

Not all the parameters can use all the settings combination.

• Extrinsic parameters (translation/rotation) are always variable.
• Distortion / Aspect Ration / Principal point cannot be unknown.

Intrinsic and Extrinsic parameters

Each camera has four intrinsic (or internal) parameters: focal length, radial distortion, pixel aspect ratio, and principal point, and some extrinsic parameters: translation (or optical center position), and rotation angles.

Intrinsic parameters are, by default, given by the camera type (shown by a little camera icon at the end the row). These parameters can simply be overridden by changing their default value or their type. for type They can also be “motion controlled” by providing a valid range for each (then shown with the icon or ). See Camera parameter types.

Extrinsic parameters are, by default, undefined (it’s what we want to find in MatchMover!). So they’re basically user defined as variable unknown (shown as ).

As intrinsic parameters, each of them can be “motion controlled”, either directly by the user or by importing motion control file (shown with an icon ). See Importing motion control data.

The General tab shows the information for the Focal Length and all the camera extrinsic parameters (translation, a.k.a optical center position, and rotation angles).

Click the first row button to define if the corresponding parameter is constant or variable over time. For example in shots where the zoom does not change throughout the sequence, set the Focal Length to fixed or constant. If you change the focal length parameter type to variable, you can then define constraints for this parameter.

• The first editable box represents the currently computed values. This can be simply edited or overridden once your shot have been calibrated for fine tuning (it has the same effect as editing the corresponding curve in the Graph Editor).
• Next, you have a button showing how the computed value relates to the initialization value. It can simply be a totally unknown parameter , or its computation can starts with an initialization value , or it can be fixed to a given value .

  Clicking on it toggles through initialized to fixed. Just empty the initialization value for “unknown” status.

• The next editable box (with a light blue background) shows the computation initial value. Next to the initialization value, you have a text box that sums up the parameter behavior (with a little popup to show the whole message if needed). For example, it will display the validity interval set by the user.
• Finally, the last button shows where the parameter configuration comes from. Either from the camera type , from the user , or from on externally imported file . Depending on the current parameter configuration, clicking on it will enable following actions:
  • Setting up a validity range
  • Removing motion control data
  Tip If you want to export the results to software that does not handle non-linear distortion or non-centered principal points (which is the case for most 3D software), do not change the default values. MatchMover compensates for the error on these parameters by adjusting the other parameters.
  Note If an export format supports anamorphism, the appropriate parameter will be set. Otherwise, the pixel aspect ratio will be enlarged in the exported file to account for the squeeze.

About the lens squeeze factor

The Lens Squeeze Factor changes the image or sequence shown in the 2D View. The following image shows the default image (top) the effects of applying a smaller lens squeeze factor that the default setting (bottom). This can be used in the case of anamorphic lenses.

Deleting a camera

To delete a camera, do one of the following:

• Select a camera in the Cameras folder in the Project window or the Track window and either:
  • Select Edit > Delete.
  • Press the Delete key.
• Right-click a camera in the Cameras folder in the Project window or the Track window and select Delete Camera from the pop-up menu.

The camera is deleted from the project.