2D Graphics Lighting

The 2D Graphics Lighting properties page enables you to control the display of lighting conditions. You can:

Use Show Outline options to define the appearance of sunlight/penumbra and penumbra/umbra transitions.
Specify the display altitude from which these transitions will be viewed during animation.
Display the subsolar point during animation.
Display nightlights.
Set the translucency options for night and day shading.

Lighting graphics will not be displayed if the central body for the 2D Graphics window is the sun.

Lighting Condition Descriptions

Lighting Condition	Description
Display Altitude	Indicates the altitude from which penumbra/umbra and sunlight/penumbra transitions are depicted during animation. STK will display the transitions as if you were sitting at the specified altitude above the surface of the central body. If you were a LEO satellite for example, you might be at about 200 km above the surface so you would see the sun before the point on the earth directly below you would.
Sunlight/Penumbra transition	Sunlit regions are those where there is total sunlight; penumbra regions are those where the Sun is partially blocked by the Earth.
Penumbra/Umbra transition	Penumbra regions are those where the Sun is partially blocked by the Earth; umbra regions are those where the Sun is totally blocked by the Earth.
Subsolar Point	If the Show is enabled, the point on the Earth directly below the Sun displays. Select the color and style of the marker that will represent the subsolar point.

Show Outline

If enabled, displays boundaries for sunlight/penumbra and penumbra/umbra transitions in the 2D Graphics window. To define the display of the boundary lines, use the following options:

Option	Description
Color	Color of the outline.
Style	Line style of the outline.
Width	Width of the outline.

Nightlights

If enabled, displays the selected nightlights image at the specified level of brightness.

Option	Description
Night Lights Level	The night lights level specifies the overall brightness of a night lights texture, where 0 means night lights are not visible, and 500 produces night lights that are easily seen.

Shading

If enabled, displays day and/or night shading in the 2D Graphics window. You can display a graduated translucency from the subsolar point to the edge of day, and from the darkest point of night to the edge of night. To define the display of shading, use the following options:

Day

Option	Description
Color	Color of shading during the day.
% Translucency at Subsolar Point	Use the slide control or enter a value (range 0-100) in the text field to set the translucency of the day shading graphics. Translucency can be adjusted from 0 to 100 percent, where 100 percent is invisible.
% Translucency at Edge of Day	Use the slide control or enter a value (range 0-100) in the text field to set the translucency of the edge of day shading graphics. Translucency can be adjusted from 0 to 100 percent, where 100 percent is invisible.

Night

Option	Description
Color	Color of shading at night.
% Translucency at Darkest Point	Use the slide control or enter a value (range 0-100) in the text field to set the translucency of the night shading graphics. Translucency can be adjusted from 0 to 100 percent, where 100 percent is invisible.
% Translucency at Edge of Night	Use the slide control or enter a value (range 0-100) in the text field to set the translucency of the edge of night shading graphics. Translucency can be adjusted from 0 to 100 percent, where 100 percent is invisible.