Raster and Projection Streams

Both the RasterStream and ProjectionStream classes within Insight3D contain an Update method for updating the objects at a specific time. In the following code sample, Update is implemented to provide raster data from the successive frames of an animated GIF, by copying each frame into the Raster from a Bitmap. Since the stream was updated, the method then returns true.

public override bool Update(JulianDate time, JulianDate nextTime)
{
    Bitmap currentFrame = m_rasterProvider.GetNextFrame();
    CopyFromBitmap(currentFrame);
    return true;
}

Note
When implementing a derived class of RasterStream, the Attributes property should be set in the constructor of the derived class.

Similarly, the Update method is implemented in the following code sample to set the projection data in ProjectionStream dynamically on each animation step:

public override bool Update(JulianDate time, JulianDate nextTime)
{
    ProjectionProviderData providerData = m_projectionProvider.Evaluate(time);
    Position = providerData.Position;
    Orientation = providerData.Rotation;
    FieldOfViewHorizontal = 0.230908805;
    FieldOfViewVertical = 0.174532925;
    NearPlane = 20.0;
    FarPlane = 10000.0;
    return true;
}

A sequence of frames of a projected raster using a raster stream and projection stream.

The relationship between the Orientation of a ProjectionStream and a Raster is shown below. In the left image, the orientation axes are shown on a raster, a frame from the video. The X axis is along the horizontal from left to right. The Y axis is along the vertical from bottom to top. The -Z axis is into the raster. In the right image, the orientation axes are drawn over a projection of that raster onto terrain.

A frame from a video with the X and Y orientation axes shown. The -Z axis is into the frame.

The same frame projected onto terrain with the orientation axes shown.

Updating of raster and projection streams is tied to the current SceneManager time and uses the RasterStreamUpdateDelta and ProjectionStreamUpdateDelta properties to allow a user to control the update rate of the data. These properties are Durations, so an update delta of 0.1 seconds will update 10 times per second while animating. If the update delta is set to 0, the stream's Update method is called every time SceneManagerTime changes. Below, the UpdateDelta property is set to 60 updates per second:

public SatelliteRasterStream()
{
    UpdateDelta = new Duration(0, 1.0 / 60.0);
    Attributes = m_rasterProvider.Attributes;
}

Note
VideoStream, which derives from RasterStream, can be used within Insight3D for easy reading of video and provides functionality to synchronize a video with the SceneManager time.

Since RasterStream and ProjectionStream derive from Raster and Projection, respectively, they can be passed to any class that accepts those base types. Below, a texture is created from a RasterStream, which is then used to create a Marker Batch Primitive:

RasterStream rasterStream = new SatelliteRasterStream();
Texture2D texture2D = SceneManager.Textures.FromRaster(rasterStream);

A sequence of frames of a marker batch primitive using a texture from a raster stream.

You can configure various visual attributes of the ProjectedRaster, such as changing the color and translucency, and also individually controlling the color and translucency of shadows, the frustum, far plane, and footprint border.

Note
To enable rendering of shadows, or the projection's frustum or far plane, set the ShowShadows, ShowFrustum, or ShowFarPlane properties to true. To enable a border around the projection's foot print, set the BorderWidth property.

The following example enables rendering of the frustum and far plane, and sets various visual properties:

EarthCentralBody earth = CentralBodiesFacet.GetFromContext().Earth;

ProjectedRaster projectedRaster = new ProjectedRaster(earth)
{
    ReferenceFrame = earth.FixedFrame,
    Raster = videoStream,
    Projection = projectionStream,
    ShowFrustum = true,
    FrustumColor = Color.Black,
    FrustumTranslucency = 0.5f,
    ShowShadows = true,
    ShadowColor = Color.Orange,
    ShadowTranslucency = 0.5f,
    ShowFarPlane = true,
    Translucency = 0.2f
};

The far plane of the projection when ShowFarPlane is enabled.

See the HowTo for the complete set of RasterStream and ProjectionStream examples shown in this overview.