VolumeLayer

A layer that renders a chunked multi-channel image source as a 3D volume.

Volume layer ray marches the loaded chunks with premultiplied blending and composites all visible channels in a single pass. The volume renders at a single level of detail taken from the policy's lod.min, so pin one with the policy when constructing the layer. While the camera moves the ray march step size is doubled to keep interaction responsive.

const source = await OmeZarrImageSource.fromHttp({ url });

const layer = new VolumeLayer({
  source,
  sliceCoords: { t: 0, c: undefined },
  policy: createExplorationPolicy({ lod: { min: 2, max: 2 } }),
  channelProps: [
    { color: "#00ffff", contrastLimits: [300, 1500] },
    { color: "#ff00ff", contrastLimits: [75, 500] },
  ],
});

viewport.addLayer(layer);

Extends Layer and inherits all public properties and methods.

Constructor

Creates a volume layer for the given source.

new VolumeLayer(props): VolumeLayer;

Parameter	Description
props: VolumeLayerProps	Initialization properties.

Types

VolumeLayerProps

Initialization properties for constructing a volume layer.

Property	Description
source: ChunkSource	The chunked image source to stream from.
sliceCoords: SliceCoordinates	Selects t and c. Spatial axes are ignored.
policy?: ImageSourcePolicy	Streaming policy. Defaults to the exploration policy.
channelProps?: ChannelProps[]	Per-channel appearance. Length must match the source.

Properties

type overrides

Identifies the layer type as VolumeLayer.

readonly type: "VolumeLayer" = "VolumeLayer";

debugShowDegenerateRays

Highlights rays of zero length for debugging. Defaults to false.

debugShowDegenerateRays: boolean = false;

relativeStepSize

Ray march step size relative to voxel size. Defaults to 1.

relativeStepSize: number = 1.0;

opacityMultiplier

Scales sample opacity during compositing. Defaults to 1.

opacityMultiplier: number = 1.0;

earlyTerminationAlpha

Alpha where a ray stops early. Defaults to 0.99.

earlyTerminationAlpha: number = 0.99;

requiresSceneDepth_ overrides

Volume ray marching reads scene depth to composite with occluding layers.

protected requiresSceneDepth_: boolean = true;

Accessors

debugShowWireframes boolean

Whether chunk bounding wireframes are drawn for debugging.

get debugShowWireframes(): boolean;

set debugShowWireframes(value): void;

Parameter	Description
value: boolean	Whether to draw chunk wireframes.

imageSourcePolicy

Sets the streaming policy at runtime and reschedules loading. The volume renders the level of detail given by the policy's lod.min.

set imageSourcePolicy(newPolicy): void;

Parameter	Description
newPolicy: ImageSourcePolicy	The policy to apply.

channelProps ChannelProps[] | undefined

The current per-channel appearance settings.

get channelProps(): ChannelProps[] | undefined;

Methods

setChannelProps() void

Applies new per-channel appearance settings to all visible volumes and notifies channel change callbacks.

setChannelProps(channelProps): void;

Parameter	Description
channelProps: ChannelProps[]	One entry per source channel.

resetChannelProps() void

Restores the channel settings passed at construction.

resetChannelProps(): void;

addChannelChangeCallback() void

Registers a callback invoked after every channel settings change.

addChannelChangeCallback(callback): void;

Parameter	Description
callback: () => void	The callback to add.

removeChannelChangeCallback() void

Removes a previously registered channel change callback.

removeChannelChangeCallback(callback): void;

Parameter	Description
callback: () => void	The callback to remove.

update() void overrides

Streams chunks for the current view and rebuilds the volume set sorted front to back. Called automatically once per frame.

update(viewport?): void;

Parameter	Description
viewport?: Viewport	The viewport being rendered.

getUniforms() Record<string, unknown> overrides

Returns the ray marching uniforms for this layer.

getUniforms(): Record<string, unknown>;