View an image

Examining 3D data from a number of different viewpoints is necessary to gain a full understanding of the nature of the data. The Viewer comprises a group of functions that provide a variety of interesting and useful ways to alter the view of the data to permit these investigations.

To run this function: Choose View > Viewing options, and then Aeroplane, Fly, Fly rotate, or Fly constrained rotate, or...

• In the Function Chooser, type VIEWER MODE ANIMATED AEROPLANE, or VIEWER MODE ANIMATED FLY, or VIEWER MODE ANIMATED ROTATE, or VIEWER MODE ANIMATE CONSTRAINED ROTATE, and press ENTER.

The viewer provides 2 different types of functions:

Mouse viewing mode functions

These functions modify the viewing mode that determines how mouse movements are interpreted while the system is waiting for a function to be executed. Any mouse movement, with a mouse button depressed, will cause the view to change subject to the current Viewer mode.

Animation functions

These functions permit the images to be rotated continuously about some axis until the escape key is pressed.

In all cases the view may be altered by pressing the left, middle or right mouse button and moving the mouse. If a three button mouse is not present, the third button may be simulated by pressing the left and right mouse buttons together. When selecting, digitising or dragging a point, the Viewer may also be invoked by pressing the Assist key. The Assist key is mapped to the F1 key. Pressing the Escape key will exit the viewer and the previous prompt to select or digitise a point will be re-displayed to allow you to continue with the previous operation.

Helpful Hints

Occasionally, while using the Viewer, you may find that the image on the screen disappears completely, this is more common when using a perspective projection. This may occur if you have rotated the image completely off the screen or, if using an animated mode, particularly Aeroplane or Fly mode, you may have flown past the data completely. To restore the image take the following actions:

• If you are using an animated motion mode, press the escape button to stop the animation.
• Press the Zoom All button or Reset View button.

Viewer Functions

A number of different Viewer functions are available to control the way in which mouse movements are interpreted while a mouse button is pressed. Mouse movements while no mouse button is pressed are ignored. Each mode can be assigned to one (or more) mouse buttons. These modes are explained in the table below.

Viewer Mode	Effect
Orbit	Up/down mouse movements orbit the camera up/down around the camera target and similarly for left/right mouse movements.
Dolly	Mouse movements move the scene in the same direction as the mouse movement. This is equivalent to Pan View in the GRAPHICS VIEW menu.
Zoom	Zoom in to or out from the image. This does not change the camera position but does change the field of view.
Z-Orbit	Very similar to the Orbit mode, the difference being the Z axis of the view always remains in the vertical plane (up or down the screen). It is not possible to tip the z axis off this vertical plane.
Pan	Up/Down movements pitch the camera up and down. Left/Right movements yaw the image to the left and right. The up direction remains unchanged.
Roll	Rolls the view in 2 dimensions around a point. You can use the Select camera target command to set the point.
Dolly In/Out	Move the camera in/out of the scene while keeping the target point fixed. The closer the camera gets to the target the more pronounced the perspective effect. Note that this movement only alters the view when using a perspective projection. It has no effect on an orthographic projection.
Cutting Planes	Only having an effect when cutting planes are activated on the screen, this option will allow the interactive movement of the cutting planes. This same effect is handled by the default setting Interactive Mouse Button on the settings form.
Constrained Dolly X	Move the image along the X-axis.
Constrained Dolly Y	Move the image along the Y-axis.
Constrained Dolly Z	Move the image along the Z-axis.
Constrained Rotate X	Rotate the image around the X-axis using the camera target as the centre of rotation.
Constrained Rotate Y	Rotate the image around the Y-axis using the camera target as the centre of rotation.
Constrained Rotate Z	Rotate the image around the Z-axis using the camera target as the centre of rotation.
Constrained Scale X	Scale the image along the X-axis.
Constrained Scale Y	Scale the image along the Y-axis.
Constrained Scale Z	Scale the image along the Z-axis.

VIEWER MODE ANIMATE CONSTRAINED ROTATE

Animated Fly Modes

The following modes map all three buttons to specific functions while the fly mode is active.

Fly Mode	Left Mouse Button	Middle Mouse Button	Right Mouse Button
Animated Aeroplane	Yoke - Treat the mouse movements like an aeroplane yoke. Up/down movements pitch the camera up and down and left/right movements roll the image to the left and right.		Forward speed - Mouse movements increase or decrease the forward speed of movement.
Animated Fly	Pan 3D - Up/down movements pitch the camera up and down and left/right movements yaw the image to the left and right. The up direction remains unchanged and so this mode is easier to use than the aeroplane mode.	Roll - Roll the image around the centre of the screen.	Forward speed - Mouse movements increase or decrease the forward speed of movement.
Animated Rotate	Orbit speed - Mouse movements control the speed at which the scene rotates about the X-axis.		Roll speed - Mouse movements control the speed at which the image rolls around the centre of the screen.
Animated Constrained Rotate	Rotate X speed - Mouse movements control the speed at which the scene rotates about the X-axis.	Rotate Y speed - Mouse movements control the speed at which the scene rotates about the Y-axis.	Rotate Z speed - Mouse movements control the speed at which the scene rotates about the Z-axis.

The viewer modes that are normally active when the system starts up are :

Left Mouse Button - Z-Orbit
Middle Mouse Button - Dolly
Right Mouse Button - Zoom

These defaults can be changed by using the Settings function. Changing the viewer mode while the software is active can easily be done.