LabelLayer

A layer that renders a 2D slice of a single-channel label image.

Label layer displays segmentation data where each pixel holds an integer label. Labels are colored by cycling through the color map's cycle with exact-value overrides in its lookupTable. Chunks stream through the same policy machinery as ImageLayer and the source must be single channel.

Clicking the layer picks the label under the pointer. With outlineSelected the picked label is outlined, and onPickValue receives the world position and label value for custom handling such as highlighting through setColorMap.

const labels = new LabelLayer({
  source: labelSource,
  sliceCoords: { z: 12, c: [0] },
  opacity: 0.55,
  blendMode: "normal",
  onPickValue: ({ value }) => console.log(`label ${value}`),
});

viewport.addLayer(labels);

Extends Layer and inherits all public properties and methods.

Constructor

Creates a label layer for the given source and slice.

new LabelLayer(props): LabelLayer;

Parameter	Description
props: LabelLayerProps	Initialization properties.

Types

LabelLayerProps

Initialization properties for constructing a label layer.

Property	Description
source: ChunkSource	The single-channel label source to stream from.
sliceCoords: SliceCoordinates	The slice to display in world units.
policy?: ImageSourcePolicy	Streaming policy. Defaults to the exploration policy.
orientation?: SliceOrientation	Slice plane orientation. Defaults to "XY".
colorMap?: LabelColorMapProps	Colors for label values. Defaults to a built-in cycle.
onPickValue?: (info) => void	Called with the picked label when the layer is clicked.
outlineSelected?: boolean	Outlines the picked label. Defaults to false.
opacity?: number	Layer opacity in [0, 1]. Defaults to 1.
blendMode?: BlendMode	How the layer blends. Defaults to "none".
occludes?: boolean	Hides content behind. Inferred from blendMode.

LabelColorMapProps

Color assignments for label values.

Values present in lookupTable use its color. Any other value takes a color from cycle by index. Value 0 renders transparent unless the lookup table assigns it a color.

Property	Description
lookupTable?: ReadonlyMap<number, ColorLike>	Exact colors for specific label values.
cycle?: ReadonlyArray<ColorLike>	Colors cycled by value. Defaults to 6 built-ins.

LabelColorMap

A validated color map with every entry resolved to a Color. Returned by LabelLayer.colorMap.

Property	Description
lookupTable: ReadonlyMap<number, Color>	Exact colors for specific label values.
cycle: ReadonlyArray<Color>	Colors cycled by value.

Properties

type overrides

Identifies the layer type as LabelLayer.

readonly type: "LabelLayer" = "LabelLayer";

Accessors

orientation SliceOrientation

The slice plane the layer displays.

get orientation(): SliceOrientation;

colorMap LabelColorMap

The validated color map currently in effect.

get colorMap(): LabelColorMap;

sliceCoords SliceCoordinates

The slice coordinates the layer displays. This is the object passed at construction and may be mutated to move through the data.

get sliceCoords(): SliceCoordinates;

source ChunkSource

The chunked label source the layer streams from.

get source(): ChunkSource;

imageSourcePolicy Readonly<ImageSourcePolicy>

The streaming policy in effect. Assign a new policy to reschedule loading at runtime, for example when switching between exploration and playback.

get imageSourcePolicy(): Readonly<ImageSourcePolicy>;

set imageSourcePolicy(newPolicy): void;

Parameter	Description
newPolicy: ImageSourcePolicy	The policy to apply.

lastPresentationTimeCoord number | undefined

The t coordinate of the most recently presented slice.

get lastPresentationTimeCoord(): number | undefined;

Methods

update() void overrides

Streams chunks for the current view and refreshes the visible slice. Called automatically once per frame.

update(viewport?): void;

Parameter	Description
viewport?: Viewport	The viewport being rendered.

setOrientation() void

Changes the slice orientation at runtime. Visible renderables are rebuilt for the new plane and chunks already resident in the shared cache are reused.

setOrientation(orientation): void;

Parameter	Description
orientation: SliceOrientation	The new slice plane.

onEvent() void overrides

Handles click picking and selection outlining. Called automatically for each pointer event on the owning viewport.

onEvent(event): void;

Parameter	Description
event: EventContext	The event with clip and world coordinates attached.

setColorMap() void

Replaces the color map and recolors all visible chunks.

setColorMap(colorMap): void;

Parameter	Description
colorMap: LabelColorMapProps	Colors for label values. Omitted fields fall back to defaults.

setSelectedValue() void

Sets the label value drawn as selected or null to clear the selection.

setSelectedValue(value): void;

Parameter	Description
value: number | null	The label value to select.

getValueAtWorld() Promise<number | null>

Reads the label value at a world position from the resident chunks. Prefers the current level of detail and falls back to other resident levels.

getValueAtWorld(world): Promise<number | null>;

Parameter	Description
world: vec3	The world-space position to sample.