Properties for the 3D Graphics Window - Advanced

Use the Advanced page of the 3D Graphics window properties to set more sophisticated options for 3D viewing. This page has the following subpanels:

Viewing
Miscellaneous
Depth Cone/Buffer Crossover
Stereo Display Options
Color Correction

If you are not familiar with the concepts associated with this page, you may want to reference Computer Graphics: Principles and Practice.

Viewing

To view a scenario in 3D, place a virtual camera among the objects in the scenario. The volume of space visible to the camera is called the view volume, with dimensions that are very small near the camera and progressively larger away from it.

You can control the viewing properties of the camera using the following parameters:

Parameter	Description
Min Visible Distance	Specify the minimum viewing distance of your camera in meters. The default is 1.0 m.
Max Visible Distance	Specify the maximum viewing distance in meters. The default is 10 million meters.
Far/Near Ratio	This is the ratio that determines the visual quality in the viewing volume. Lower values increase the visual quality. The default value is 1000; AGI recommends that you not change this value.
Field of View	Specify how wide of an angle you can see, in degrees, in the 3D Graphics window. The larger the value, the more you can see. The maximum angle is 160 degrees. A large field of view is similar to a wide-angle lens in photography, where size differences are exaggerated due to proximity to the camera. A small field of view is similar to a telescopic lens.

Miscellaneous

Make selections regarding the following options:

Option	Description
Use Wireframe Mode	Select this check box to display all polygons as wireframes. This is useful for checking the complexity of the models in a scenario.
Hide Cursor	The cursor may display in output images on certain computers. In those cases, you can stop the cursor from displaying by selecting this check box. If selected, the cursor does not appear in output images when recording and using window snap options.
Use Joystick	Select this check box to use a joystick, in addition to the mouse, to navigate in the 3D Graphics window.

Depth Cone/Buffer Crossover

There are two ways that STK uses Open Graphics Library (OpenGL) to determine what is in front of or behind a central body: the depth cone and the depth buffer.

The depth cone prevents items from sinking into the central body. This works well for surface items, such as latitude and longitude lines. However, it does not work well for below-surface items, such as a terrain with negative altitude values. The depth cone also improperly displays the horizon when viewing from low altitudes. You can correct these conditions by enabling STK to use the depth buffer for low altitudes. The depth buffer properly displays the horizon and prevents displaying below-surface items.

Parameter	Description
Use	Select this check box to use both a depth cone and a depth buffer. STK will then use the depth cone for viewing from above the Crossover Altitude and the depth buffer for viewing below the Crossover Altitude. If you do not select the check box, STK will use only the depth cone.
Crossover Altitude	If you select Use, set the altitude that STK will use to determine whether to use the depth cone or depth buffer.

Stereo Display Options

You can use 3D (stereoscopic) glasses to view scenarios in STK using the following parameters:

Parameter	Description
Use	Select this check box to display and record in stereo. You must select this to specify the other parameters in this table.
Type	From the shortcut menu, choose one of the following types of stereo display: Red/Blue Stereo displays anaglyph 3D in the 3D Graphics window. You will need red/blue 3D glasses to see the 3D effect. Side by Side displays left-eye and right-eye views beside each other in the 3D Graphics window. Left Eye View displays only the left-eye view in the 3D Graphics window. Right Eye View displays only the right-eye view in the 3D Graphics window. Virtual Reality Device: Select this to use a compatible Virtual Reality (VR) headset with STK. STK supports VR systems that work through Oculus Home or SteamVR. STK will display to the VR headset and attach the VR system's head-tracking to the STK camera. The scene, as viewed through the VR device, is also mirrored in STK's existing 3D Graphics window. Head-tracking enables you to turn your head to look around the scene with the camera in a stationary position. You can use the VR system's controllers (analog stick or touch pad) to move the camera's position within the scene. One hand controls the camera's basic position; this is equivalent to a left-click and drag with a mouse. The other hand controls the camera zoom; this is equivalent to a right-click and drag with a mouse or using the mouse scroll wheel. Open GL View: This option is available only if your system supports the quadbuffer stereo mode. To effectively use the Open GL View option, you must first enable the Support Stereo Viewing option at the application level before creating the 3D Graphics window in which images are to be captured.
Projection	From the shortcut menu, choose one of the following types of projections: Automatic: If you select this option, the Projection Distance setting is disabled, automatically setting the value to the distance between the "From" and "To" objects in 3D Graphics window. When the camera zooms in or out, the object may appear to grow and shrink (staying in the screen) rather than move closer or farther from the viewer. Fixed Distance: Select this to have the left eye and right eye both aim a a specific distance away. Parallel: If you select this option, the Projection Distance setting is disabled and the focal length is infinite.
Eye Separation Factor	The default eye separation factor is 0.02. Increasing this number will increase the overall left/right eye separation, which makes the image appear to have more depth. Be careful when increasing the Eye Separation Factor. If the value is too high, the separation between distant objects will be wider than the distance between the viewer's eyes, causing the image to be out of focus. Also, if the separation is too large, viewers cannot focus on distant parts of the image and may experience eyestrain while attempting to do so. Having too small of an Eye Separation Factor causes the image to appear not as "deep" as it should look and distant objects, such as stars, to appear to be very far away. But the image still appears to be three-dimensional. The correct setting for the Eye Separation Factor is actually dependent on the physical size of the display on which the image is shown. A relatively large setting, like 0.08, might look fine on a small monitor where the separation works out to be only about an inch or so, easily less than the distance between the viewer's eyes. The very same image displayed on a giant wall projection system may produce a separation of several inches, growing larger than the distance between the viewer's eyes.
Projection Distance	This parameter is active when you select Fixed Distance as the Projection. When displaying in stereo, there are two virtual cameras, one for the left eye and one for the right eye. These cameras both look in the same general direction, each aimed at a point a fixed distance away. This distance is called the Projection Distance. It should be about the same distance that the cameras are from the nearest visible object. Objects in the 3D Graphics window that get closer than the projection distance will appear to pop out of your monitor in 3D. If this is done carefully, it can create a dramatic 3D effect. If it is pushed too far, the 3D effect will break down or cause eye strain.

The Left/Right Eye View stereo recording is for advanced users only. They offer full-color, full-resolution access to the left and right views, which are not available in the other stereo modes. Using these options, you can create a view path and render two movies: one from the left eye of that view path and another from the right eye of the same view path. The two movies could be post-processed to be in virtually any format needed to drive stereo viewing equipment. Some additional handling is needed to get one video stream to the left eye and the other to the right eye.

Color Correction

You can adjust the 3D Graphics color and brightness/contrast by entering values or moving the slider for the following parameters:

Quality	Description
Brightness	Adjust the overall screen brightness of the 3D Graphics window. Values range from -127 to +127, with the default being zero.
Contrast	Adjust the brightness difference between the darkest and lightest points. Values range from -127 to +127, with the default being zero.
Gamma	Adjust the luminance on the 3D Graphics window to achieve ideal color for your monitor. Enter a real number between 0.0 and 16.0. The default is 1.0.