Symbology Reference¶
osgEarth renders features and annotations using stylesheets. This document lists all the symbol properties available for use in a stylesheet. Not every symbol is applicable to every situation; this is just a master list.
Jump to a symbol:
Developer Note:
*In the SDK, symbols are in theosgEarth::Symbologynamespace, and each symbol class is in the formAltitudeSymbolfor example. Properties below are as they appear in the earth file; in the SDK, properties are available via accessors in the formLineSymbol::strokeWidth()etc.
Value Types¶
These are the basic value types. In the symbol tables on this page, each property includes the value type in parentheses following its description.
float: Floating-point number float with units: Floating-point number with unit designator, e.g. 20px (20 pixels) or 10m (10 meters) HTML_Color: Color string in hex format, as used in HTML; in the format #RRGGBB or #RRGGBBAA. (Example: #FFCC007F) integer: Integral number numeric_expr: Expression (simple or JavaScript) resolving to a number string: Simple text string boolean: true or false string_expr: Expression (simple or JavaScript) resolving to a text string uri_string: String denoting a resource location (like a URL or file path). URIs can be absolute or relative; relative URIs are always relative to the location of the referrer, i.e. the entity that requested the resource. (For example, a relative URI within an earth file will be relative to the location of the earth file itself.)
Geometry¶
Basic geometry symbols (SDK: LineSymbol, PolygonSymbol, PointSymbol)
control the color and style of the vector data.
Altitude¶
The altitude symbol (SDK: AltitudeSymbol) controls a feature’s interaction with
the terrain under its location.
| Property | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| altitude-clamping |
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| altitude-technique | When
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| altitude-binding | Granularity at which to sample the terrain when
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| altitude-resolution | Elevation data resolution at which to sample terrain height when
altitude-technique is map (float) |
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| altitude-offset | Vertical offset to apply to geometry Z | ||||||||
| altitude-scale | Scale factor to apply to geometry Z |
Tip: You can also use a shortcut to activate draping or GPU clamping; set altitude-clamping
to either terrain-drape or terrain-gpu.
Extrusion¶
The extrusion symbol (SDK: ExtrusionSymbol) directs osgEarth to create extruded
geometry from the source vector data; Extrusion turns a 2D vector into a 3D shape.
Note: The simple presence of an extrusion property will enable extrusion.
| Property | Description |
|---|---|
| extrusion-height | How far to extrude the vector data (numeric-expr) |
| extrusion-flatten | Whether to force all extruded vertices to the same Z value (bool).
For example, if you are extruding polygons to make 3D buildings,
setting this to true will force the rooftops to be flat even
if the underlying terrain is not. (boolean) |
| extrusion-wall-gradient | Factor by which to multiply the fill color of the extruded
geometry at the base of the 3D shape. This results in the 3D
shape being darker at the bottom than at the top, a nice effect.
(float [0..1]; try 0.75) |
| extrusion-wall-style | Name of another style in the same stylesheet that osgEarth should apply to the walls of the extruded shape. (string) |
| extrusion-roof-style | Name of another style in the same stylesheet that osgEarth should apply to the roof of the extruded shape. (string) |
Skin¶
The skin symbol (SDK: SkinSymbol) applies texture mapping to a geometry, when applicable.
(At the moment this only applies to extruded geometry.)
| Property | Description |
|---|---|
| skin-library | Name of the resource library containing the skin(s) |
| skin-tags | Set of strings (separated by whitespace containing one or more
resource tags. When selecting a texture skin to apply, osgEarth
will limit the selection to skins with one of these tags. If you
omit this property, all skins are considered. For example, if you
are extruding buildings, you may only want to consider textures
with the building tag. (string) |
| skin-tiled | When set to true, osgEarth will only consider selecting a skin
that has its tiled attribute set to true. The tiled
attribute indicates that the skin may be used as a repeating
texture. (boolean) |
| skin-object-height | Numeric expression resolving to the feature’s real-world height (in meters). osgEarth will use this value to narrow down the selection to skins appropriate to that height (i.e., skins for which the value falls between the skin’s min/max object height range. (numeric-expr) |
| skin-min-object-height | Tells osgEarth to only consider skins whose minimum object height is greater than or equal to this value. (numeric-expr) |
| skin-max-object-height | Tells osgEarth to only consider skins whose maximum object height is less than or equal to this value. (numeric-expr) |
| skin-random-seed | Once the filtering is done (according to the properties above, osgEarth determines the minimal set of appropriate skins from which to choose and chooses one at random. By setting this seed value you can ensure that the same “random” selection happens each time you run the application. (integer) |
Icon¶
The icon symbol (SDK: IconSymbol) describes the appearance of 2D icons.
Icons are used for different things, the most common being:
- Point model substitution - replace geometry with icons
- Place annotations
| Property | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| icon | URI of the icon image. (uri-string) | ||||||||
| icon-library | Name of a resource library containing the icon (optional) | ||||||||
| icon-placement | For model substitution, describes how osgEarth should replace geometry with icons:
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| icon-density | For icon-placement settings of interval or random,
this property is hint as to how many instances osgEarth should
place. The unit is approximately “units per km” (for linear data)
or “units per square km” for polygon data. (float) |
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| icon-scale | Scales the icon by this amount (float) | ||||||||
| icon-heading | Rotates the icon along its central axis (float, degrees) | ||||||||
| icon-declutter | Activate decluttering for this icon. osgEarth will attempt to automatically show or hide things so they don’t overlap on the screen. (boolean) | ||||||||
| icon-align | Sets the icon’s location relative to its anchor point. The valid values are in the form “horizontal-vertical”, and are:
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| icon-random-seed | For random placement operations, set this seed so that the randomization is repeatable each time you run the app. (integer) | ||||||||
| icon-occlusion-cull | Whether to occlusion cull the text so they do not display when line of sight is obstructed by terrain | ||||||||
| icon-occlusion-cull-altitude | The viewer altitude (MSL) to start occlusion culling when line of sight is obstructed by terrain |
Model¶
The model symbol (SDK: ModelSymbol) describes external 3D models.
Like icons, models are typically used for:
- Point model substitution - replace geometry with 3D models
- Model annotations
| Property | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| model | URI of the 3D model (uri-string). Use this OR the
model-library property, but not both. |
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| model-library | Name of a resource library containing the model. Use this OR
the model property, but not both. |
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| model-placement | For model substitution, describes how osgEarth should replace geometry with models:
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| model-density | For model-placement settings of interval or random,
this property is hint as to how many instances osgEarth should
place. The unit is approximately “units per km” (for linear data)
or “units per square km” for polygon data. (float) |
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| model-scale | Scales the model by this amount along all axes (float) | ||||||||
| model-heading | Rotates the about its +Z axis (float, degrees) | ||||||||
| icon-random-seed | For random placement operations, set this seed so that the randomization is repeatable each time you run the app. (integer) |
Render¶
The render symbol (SDK: RenderSymbol) applies general OpenGL rendering settings as well
as some osgEarth-specific settings that are not specific to any other symbol type.
| Property | Description |
|---|---|
| render-depth-test | Enable or disable GL depth testing. (boolean) |
| render-lighting | Enable or disable GL lighting. (boolean) |
| render-transparent | hint to render in the transparent (depth-sorted) bin (boolean) |
| render-bin | render bin to use for sorting (string) |
| render-depth-offset | Enable or disable Depth Offsetting. Depth offsetting is a GPU technique that modifies a fragment’s depth value, simulating the rendering of that object closer or farther from the viewer than it actually is. It is a mechanism for mitigating z-fighting. (boolean) |
| render-depth-offset-min-bias | Sets the minimum bias (distance-to-viewer offset) for depth offsetting. If is usually sufficient to set this property; all the others will be set automatically. (float, meters) |
| render-depth-offset-max-bias | Sets the minimum bias (distance-to-viewer offset) for depth offsetting. |
| render-depth-offset-min-range | Sets the range (distance from viewer) at which to apply the minimum depth offsetting bias. The bias graduates between its min and max values over the specified range. |
| render-depth-offset-max-range | Sets the range (distance from viewer) at which to apply the maximum depth offsetting bias. The bias graduates between its min and max values over the specified range. |
Text¶
The text symbol (SDK: TextSymbol) controls the existence and appearance of text labels.
| Property | Description |
|---|---|
| text-fill | Foreground color of the text (HTML color) |
| text-size | Size of the text (float, pixels) |
| text-font | Name of the font to use (system-dependent). For example, use “arialbd” on Windows for Arial Bold. |
| text-halo | Outline color of the text; Omit this property altogether for no outline. (HTML Color) |
| text-halo-offset | Outline thickness (float, % of glyph width, default 0.0625) |
| text-offset-x | The x offset of the text in % of glyph width, default 0.0625 |
| text-offset-y | The y offset of the text in % of glyph width, default 0.0625 |
| text-align |
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| text-layout |
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| text-content | The actual text string to display (string-expr) |
| text-encoding |
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| text-declutter | Activate decluttering for this icon. osgEarth will attempt to automatically show or hide things so they don’t overlap on the screen. (boolean) |
| text-occlusion-cull | Whether to occlusion cull the text so they do not display when line of sight is obstructed by terrain |
| text-occlusion-cull-altitude | The viewer altitude (MSL) to start occlusion culling when line of sight is obstructed by terrain |
Coverage¶
The coverage symbol (SDK: CoverageSymbol) controls how a feature is rasterized into
coverage data with discrete values.
| Property | Description |
|---|---|
| coverage-value | Expression resolving to the floating-point value to encode. |