The David Rumsey Collection interactive 3D GIS Viewer uses three viewing modes developed specifically for this application: Fly-Through, Inspection, and Hover. Use the space bar to advance through the three viewing modes.

Fly-Through:

1. Holding down the up arrow key accelerates the Virtual Vehicle forward, when the arrow key is released, the vehicle continues to move forward at the current speed.

2. Tapping the up arrow key after accelerating reduces the speed to a pre-set idle speed.

3. After accelerating the user may also decelerate by holding down the down arrow key.

4. If the user continues to hold down the down arrow key, the virtual vehicle will eventually come to a halt, and begin to move in reverse.

5. The left and right arrow keys move the virtual vehicle laterally.

6. In the Fly-Through control set the mouse is used to rotate the virtual vehicle 360 deg. in any direction.

Inspection:

1. The up and down arrow keys tilt the landscape back and forth, pivoting on a central point.

2. The left and right arrow keys rotate the landscape around a central point.

3. The page up and page down keys are used to zoom in and zoom out.

4. The central point, around which the landscape moves, can be re-positioned using the "w", "a", "s", and "d" keys. The "w" and "s" keys move the point forward and backward, the "a" and "d" keys can be used to "steer".

Hover:

1. The up and down arrow keys are used to tilt the virtual vehicle.When the virtual vehicle is pointing down, perpendicular to the horizon, it is motionless. As it tilts toward the horizon, it accelerates. When it is pointing at the horizon, parallell to the landscape, it is moving at maximum speed.

2. The left and right arrow keys cause the virtual vehicle to roll, and turn left and right.

3. The keyboard "1" key causes the virtual vehicle to decend, the keyboard "2" key causes the virtual vehicle to ascend.

Helpful 3D Viewer Concepts:

Virtual Vehicle: The Virtual Vehicle is the users point of view. The various 3D viewing modes operate by moving the virtual vehicle in relation to the landscape.

Controls Set: The movements that can be performed by the Virtual Vehicle are activated using the mouse, and/or various keyboard keys. The combination of available movements and their activating keys are refered to as viewing modes. Currently there are three different viewing modes: Fly-Through, Inspection, and Hover.

Landscape: The landscape is made up of two-dimensional maps draped over three-dimensional elevation data. The landscapes in our interactive 3D GIS Viewer behave somewhat differently than you might expect. In the interactive 3D GIS Viewer it is possible to pass through the landscape and view it from the "bottom". This can be confusing for new users.

Directions in 3D:

X Axis: From the users point of view the X Axis extends left to right, horizontally.

Y Axis: From the users point of view the Y Axis extends vertically perpendicular to the X Axis.

Z Axis: The Z Axis extends from the user, to the horizon, perpendicular to the X and Y axes.

Pitch: Pitch can be defined as tilting back and forth along the Z-Axis.

Roll: Roll can be defined as tilting back and forth along the X Axis.

Yaw: Yaw can be defined as rotating horizontally.

Any of the above terms can be applied to the landscape or the Virtual Vehicle. This can be a little confusing, because we are used to a "static" landscape and moving vehicles. In the "Inspection" control set, the landscape appears to be moving, and the vehicle appears to be stationary. In actuality the vehicle is orbiting the landscape. For the purposes of understanding the controls, it is useful to imagine that the landscape is moving and the vehicle is stationary.