OpenLIME

Class: LayerMultispectral

LayerMultispectral

LayerMultispectral - Advanced multispectral imagery visualization layer

This layer provides specialized handling of multispectral image data with configurable visualization modes and interactive spectral analysis capabilities through Color Twist Weights (CTW). It supports scientific visualization workflows for remote sensing, art analysis, medical imaging, and other multispectral applications.

Features:

  • Multiple visualization modes (RGB, single band)
  • UBO-optimized Color Twist Weights implementation for real-time spectral transformations
  • Preset system for common visualization configurations (false color, etc.)
  • Support for multiple image layouts and tiling schemes
  • Compatible with both single images and tile-based formats (DeepZoom, etc.)

Technical implementation:

  • Uses WebGL2 features for efficient processing
  • Implements shader-based visualization pipeline
  • Supports multiple image layouts and tiling schemes

new LayerMultispectral(options)

Creates a new LayerMultispectral instance

Parameters:
Name Type Description
options LayerMultispectralOptions

Configuration options
Source:
Throws:

  • If rasters options is not empty (rasters are created automatically)

    Type
    Error

  • If url to info.json is not provided

    Type
    Error

  • If presets option is not provided

    Type
    Error
Example
// Create multispectral layer with deepzoom layout
const msLayer = new OpenLIME.Layer({
  type: 'multispectral',
  url: 'path/to/info.json',
  layout: 'deepzoom',
  defaultMode: 'rgb',
  presets: 'path/to/presets.json'
});

// Add to viewer
viewer.addLayer('ms', msLayer);

// Apply a preset CTW
msLayer.applyPreset('falseColor');

Extends

Methods

addControl(name, value)

Adds a shader parameter control

Parameters:
Name Type Description
name string

Control identifier
value *

Initial value
Inherited From:
Overrides:
Source:
Throws:

If control already exists

Type
Error

addShader(id, shader)

Adds a shader to the layer's available shaders

Parameters:
Name Type Description
id string

Unique identifier for the shader
shader Shader

Shader instance to add
Inherited From:
Overrides:
Source:
Throws:

If shader with the same id already exists

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
const customShader = new OpenLIME.Shader({...});
layer.addShader('custom', customShader);
layer.setShader('custom');
```

addShaderFilter(filter)

Adds a filter to the current shader

Parameters:
Name Type Description
filter Object

Filter specification
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

applyPreset(presetName)

Applies a preset CTW from the presets library

Loads and applies a predefined set of CTW coefficients for specialized visualization (e.g., false color, vegetation analysis).

Parameters:
Name Type Description
presetName string

Name of the preset
Source:
Throws:

If preset doesn't exist

Type
Error

boundingBox()

Gets layer bounding box in scene coordinates

Inherited From:
Overrides:
Source:
Returns:

Bounding box

Type
BoundingBox

clearShaderFilters(name)

Removes all filters from the current shader

Parameters:
Name Type Description
name Object

Filter name
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

derive( [options])

Creates a new Layer that shares tiles with this layer but uses a different shader. This method allows efficient creation of derivative layers that share the same source textures, which is useful for applying different visual effects to the same image data without duplicating resources.

Parameters:
Name Type Argument Default Description
options Object <optional>
 {}

Options for the new layer

Properties
Name Type Argument Description
shaders Object <optional>

Map of shaders for the new layer
defaultShader string <optional>

ID of shader to set as active
label string <optional>

Label for the new layer (defaults to original label)
zindex number <optional>

Z-index for the new layer (defaults to original + 1)
visible boolean <optional>

Layer visibility (defaults to same as original)
transform Transform <optional>

Custom transform (defaults to copy of original)
mipmapBias number <optional>

Custom mipmap bias (defaults to original value)
pixelSize number <optional>

Custom pixel size (defaults to original value)
debug boolean <optional>

Debug mode flag (defaults to original value)
Inherited From:
Overrides:
Source:
Returns:

A new layer sharing textures with this one

Type
Layer
Example
```javascript
// Create a derived layer with edge detection shader
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = originalLayer.derive({
    label: 'Edge Detection',
    shaders: { 'edge': enhancedShader },
    defaultShader: 'edge',
    zindex: 10
});
viewer.addLayer('edges', derivedLayer);
```
or
```javascript
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = layer.derive({
    label: 'Enhanced Image'
});
derivedLayer.addShader('enhanced', enhancedShader);
derivedLayer.setShader('enhanced');
viewer.addLayer('Enhanced Image', derivedLayer);
```

getAvailablePresets()

Gets available presets

Returns the names of all available preset CTW configurations.

Source:
Returns:

Array of preset names

Type
Array.<string>

getBandCount()

Gets the number of spectral bands

Returns the count of spectral planes in the multispectral dataset.

Source:
Returns:

Number of bands

Type
number

getControl(name)

Gets the shader parameter control corresponding to name

Parameters:
Name Type Description
name *

The name of the control. return {*} The control
Inherited From:
Overrides:
Source:

getMode()

Gets the current shader visualization mode

Inherited From:
Overrides:
Source:
Returns:

Current mode or null if no shader

Type
string | null

getModes()

Gets available shader modes

Inherited From:
Overrides:
Source:
Returns:

Array of available modes

Type
Array.<string>

getPixelValues(x, y)

Gets pixel values for a specific pixel location Works with both single images and tiled formats

Parameters:
Name Type Description
x number

X coordinate in image space (0,0 at top-left)
y number

Y coordinate in image space (0,0 at top-left)
Inherited From:
Overrides:
Source:
Returns:

Array containing RGBA values for each raster at the specified pixel

Type
Array.<Uint8Array>

getPreset(presetName)

Gets a preset CTW configuration by name

Retrieves the preset's red, green, and blue CTW arrays from the presets collection.

Parameters:
Name Type Description
presetName string

Name of the preset
Source:
Returns:

Object with red, green, blue arrays or null if not found

Type
Object | null

getSpectrum(x, y)

Gets spectrum data for a specific pixel

For tiled formats, this method finds the appropriate tiles and reads the spectral values.

Parameters:
Name Type Description
x number

X coordinate in image space
y number

Y coordinate in image space
Source:
Returns:

Array of spectral values (0-100)

Type
Array.<number>

getSpectrum(x, y)

Gets spectrum data for a specific pixel

Uses the improved getPixelValues method from the base Layer class to obtain spectral values across all bands.

Parameters:
Name Type Description
x number

X coordinate in image space
y number

Y coordinate in image space
Source:
Returns:

Array of spectral values (0-100)

Type
Array.<number>

getState( [stateMask])

Gets the current layer state

Parameters:
Name Type Argument Default Description
stateMask Object <optional>
 null

Optional mask to filter returned state properties
Inherited From:
Overrides:
Source:
Returns:

Current state object

Type
Object

getWavelengths()

Gets the wavelength array for spectral bands

Returns the wavelength values (in nm) for each spectral band.

Source:
Returns:

Array of wavelengths

Type
Array.<number>

info()

Gets info

Source:
Returns:

Object with info on multispectral dataset or null if not found

Type
Object | null

interpolateControls()

Updates control interpolation

Inherited From:
Overrides:
Source:
Returns:

Whether all interpolations are complete

Type
boolean

<async> loadTile(tile, callback)

Loads and processes a single image tile with optimized resource management. Implements request batching, concurrent loading, and proper error handling.

Parameters:
Name Type Description
tile Object

Tile specification object

Properties
Name Type Argument Description
index string

Unique tile identifier
url string

Base URL for tile resource
start number <optional>

Start byte for partial content (for tarzoom)
end number <optional>

End byte for partial content (for tarzoom)
offsets Array.<Object> <optional>

Byte offsets for interleaved formats
callback function

Completion callback(error, size)
Inherited From:
Overrides:
Source:
Throws:

If tile is already in processing queue

Type
Error
Returns:
Type
Promise.<void>

pixelSizePerMM()

Gets pixel size in millimeters

Inherited From:
Overrides:
Source:
Returns:

Size of one pixel in mm

Type
number

removeShader(id)

Removes a shader from the layer's available shaders

Parameters:
Name Type Description
id string

Identifier of the shader to remove
Inherited From:
Overrides:
Source:
Throws:

If shader with the specified id doesn't exist

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
// Remove a shader that's no longer needed
layer.removeShader('oldEffect');
```

removeShaderFilter(name)

Removes a filter from the current shader

Parameters:
Name Type Description
name Object

Filter name
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

scale()

Gets layer scale

Inherited From:
Overrides:
Source:
Returns:

Current scale value

Type
number

setCTW(redCTW, greenCTW, blueCTW)

Sets Color Twist Weights coefficients manually

CTW coefficients define how spectral bands are combined to create RGB visualization. Each array contains weights for each spectral band.

Parameters:
Name Type Description
redCTW Float32Array

Red channel coefficients
greenCTW Float32Array

Green channel coefficients
blueCTW Float32Array

Blue channel coefficients
Source:
Throws:

If arrays have incorrect length

Type
Error

setControl(name, value [, dt] [, easing])

Sets a shader control value with optional animation

Parameters:
Name Type Argument Default Description
name string

Control identifier
value *

New value
dt number <optional>

Animation duration in ms
easing string <optional>
 'linear'

Easing function
Inherited From:
Overrides:
Source:
Fires:

setMode(mode)

Sets the visualization mode

Changes how multispectral data is visualized:

  • 'rgb': Uses CTW coefficients to create RGB visualization
  • 'single_band': Shows a single spectral band
Parameters:
Name Type Description
mode string

Mode name ('rgb', 'single_band')
Overrides:
Source:

setShader(id)

Sets the active shader

Parameters:
Name Type Description
id string

Shader identifier from registered shaders
Inherited From:
Overrides:
Source:
Fires:
Throws:

If shader ID is not found

Type
Error

setSingleBand(bandIndex [, channel])

Sets single band visualization

Displays a single spectral band on a specific output channel.

Parameters:
Name Type Argument Default Description
bandIndex number

Index of band to visualize
channel number <optional>
 0

Output channel (0=all/gray, 1=R, 2=G, 3=B)
Source:

setState(state [, dt] [, easing])

Sets the layer state with optional animation

Parameters:
Name Type Argument Default Description
state Object

State object with controls and mode
dt number <optional>

Animation duration in ms
easing string <optional>
 'linear'

Easing function ('linear'|'ease-out'|'ease-in-out')
Inherited From:
Overrides:
Source:

setTransform(tx)

Sets the layer's transform

Parameters:
Name Type Description
tx Transform

New transform
Inherited From:
Overrides:
Source:
Fires:
  • Layer#event:updateSize

setViewport(view)

Sets the layer's viewport

Parameters:
Name Type Description
view Object

Viewport specification

Properties
Name Type Description
x number

X position
y number

Y position
dx number

Width
dy number

Height
Inherited From:
Overrides:
Source:
Fires:

setVisible(visible)

Sets layer visibility

Parameters:
Name Type Description
visible boolean

Whether layer should be visible
Inherited From:
Overrides:
Source:
Fires:

setZindex(zindex)

Sets layer rendering order

Parameters:
Name Type Description
zindex number

Stack order value
Inherited From:
Overrides:
Source:
Fires:

Events

ready

The event is fired when a layer is initialized.

Inherited From:
Overrides:
Source:

update

The event is fired if a redraw is needed.

Inherited From:
Overrides:
Source: