General Panel

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The “General” sub-panel manages general information pertaining to the currently selected flight path. The following parameters can be set:

Name: The name of the flight path.

Group: The flight path group this flight path belongs to. If the entered group name does not yet exist, a new group with this name is created.

Length: The duration of the current flight path in seconds.

Looped path: The current flight path is also interpolated between the last and the first control point thereby creating a looped path.

Constant speed: Determines if the attached objects have the same speed all along the flight path or if their speed is determined by a linear interpolation of the control points speed values. The easiest way to create a flight path with variable speed is to enable the “Auto max speed” feature and disable the “Constant speed” flag BEFORE adding the control points.

Position from: The positions of the flight path are interpolated from the control point positions and one of the following additional information type: the tangent scale, the tangent scale and the forward direction or no additional information in the case of “Automatic”.



Tangent Scale

Tangent Scale & Forward Direction

Automatic

?

The path is defined by the control point positions and the tangent scales (see “Control Points” section)

The path is defined by the control point positions, the tangent scales (see “Control Points” section) and the direction of the control point forward vectors (green arrows)

The path is solely defined by the control point positions

+

+ Creates a smooth curve in most cases. The tangent scale must can adjusted to fine-tune the curve

+ Smooth looped paths

+ The forward direction defines the path direction, which means design freedom.

+ Smooth looped paths

+ Always creates a smooth curve, independent of the control point spacing

+ No additional information is required

-

- If the control points are far apart or close together, the tangent scales of the control points have to be adjusted for a smooth curve

- The curvature heavily depends on the tangent scales, which means more work to do

- The method cannot create a smooth transition for looped paths automatically, there will be a kink at the first control point


Orientation from: The orientation of an attached object is calculated using either the control point forward and up direction or they are calculated automatically.



Forward & Up Direction

Automatic

?

The orientation of an attached object is defined by a forward and up vector at every control point. The forward vector is represented by a green arrow, the up vector by a blue arrow

The orientation of an attached object is chosen in such a way that the object will always look in the direction of the path while the local up vector of the object is always as vertical as possible

+

+ Full control of the object orientation

+ Saves a lot of work

-

- More work to do

- Objects cannot roll

Control point size: The Diameter of the control point “knob” (sphere on top). This does not influence the flight path in any way, it just makes the visualized control points larger.

Place control point at camera position: If this parameter is enabled, a new control point is inserted at the current position of the camera. Otherwise, a new control point will appear in front of the camera so it can be manipulated.

Show tangent vectors: This parameter controls whether the tangential direction at each control point is shown or not. The tangential direction is indicated by a red arrow.


A few examples will illustrate the different interpolations:

This flight path was created with “Tangent Scale & Forward Direction” for the positions.

The curve leaves each control point in the direction of the forward vector (green arrow).

The blue arrow (up vector) does not influence the calculated positions.

This flight path was created with “Automatic” positions and “Forward & Up Direction” for the orientation.

The attached object is looking in direction of the forward vector (green arrow) and the upward direction of the object is controlled by the control point up vector (blue arrow)

The up vector is used to roll the object.

Here, the problem with “Automatic” for position interpolation is illustrated.

If the path is looped, there will be a kink where the first control point is.

The problem can be solved if the last control point is positioned in such way that the kink is about 180°


Control Points

With the button “New”, a new control point is placed, with “Del”, the currently selected control point is deleted. The two buttons “Up” and “Down”, can be used to change the order of the control points.



To create a control point, simply navigate to where it should be placed and press the “New” button right of the control point list. The newly created control point will be selected in the list and highlighted in the view. Depending on the currently chosen interpolation methods, a control point assumes a different appearance.


A control point can be translated much like a 3D model by using the mouse in combination with the Shift key. To modify the control points frame, the track ball paradigm is used: Dragging the mouse over the head of the control point will cause a rotation in this direction. In what follows, the options in the control point panel are explained in detail.

In order to create a flight path there must be at least two control points. For a Catmull-Rom or B-Spline vector interpolation together with tangential orientation, only the control points positions are relevant. When using quaternion spline interpolation or viewing direction vector interpolation,  orientation information is needed at each control point. In TerrainView™ this orientation information is visualized by adding two arrows to a control point, representing the forward and upward direction.





Control point for Catmull-Rom or B-Spline interpolation

Control point with orientation information. The green arrow represents the forward direction, the blue one the upward direction and the red arrow indicates the tangent direction.


The green and blue arrows that are visible for quaternion spline interpolation represent the orientation at the control point and are called the frame vectors of the control point. Additionally, the tangent vectors can be visualized by red arrows.