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Viewshed Area Analysis

DMap3D.analysis.viewshedArea performs regional visibility analysis based on frustum, displaying visible/invisible areas in the scene.

Import​

import DMap3D from 'dmap3d'
import * as Cesium from 'cesium'

Basic Usage​

const viewer = new Cesium.Viewer('cesiumContainer')

// Create viewshed area analysis tool
const viewshedArea = new DMap3D.analysis.viewshedArea(viewer)

// Interactive analysis (click two points: observer point and direction point)
viewshedArea.startAnalysis()

Constructor​

new DMap3D.analysis.viewshedArea(viewer, options?)​

Parameters:

  • viewer - Cesium.Viewer instance
  • options? - Optional configuration

Options:

interface ViewshedAreaOptions {
  baseColor?: string           // Wireframe color
  visibleColor?: string        // Visible area color
  invisibleColor?: string      // Invisible area color
  visibleColorAlpha?: number   // Visible area opacity (0-1)
  invisibleColorAlpha?: number // Invisible area opacity (0-1)
  fovx?: number                // Horizontal field of view (1-130 degrees)
  fovy?: number                // Vertical field of view (1-179 degrees)
  lineWidth?: number           // Wireframe width
  useLighting?: boolean        // Whether to use lighting
  heightOffset?: number        // Observer height offset
  showFrustumRefLines?: boolean // Whether to show reference lines
}

Methods​

startAnalysis()​

Start interactive analysis. The user clicks two points in the scene (observer point and direction point).

viewshedArea.startAnalysis()

setPositionAnalysis(params)​

Set analysis area directly via coordinates, without interaction.

viewshedArea.setPositionAnalysis({
  startPosition: [116.4074, 39.9042, 100],  // [longitude, latitude, height]
  endPosition: [116.4174, 39.9142, 50]
})

destroy()​

Destroy the tool and release resources.

viewshedArea.destroy()

Dynamic Properties​

The following properties can be dynamically adjusted after analysis:

// Field of view adjustment
viewshedArea.fovx = 90        // Horizontal field of view (1-130 degrees)
viewshedArea.fovy = 60        // Vertical field of view (1-179 degrees)

// Range and angle
viewshedArea.radiusScale = 1.5      // Analysis range scale
viewshedArea.offsetHeading = 30     // Horizontal rotation angle
viewshedArea.offsetPitch = -10      // Vertical rotation angle

// Color settings
viewshedArea.visibleColor = '#00FF00'
viewshedArea.invisibleColor = '#FF0000'
viewshedArea.visibleColorAlpha = 0.5
viewshedArea.invisibleColorAlpha = 0.5

// Other
viewshedArea.heightOffset = 1.8     // Observer height offset
viewshedArea.useLighting = true     // Use lighting
viewshedArea.showFrustumRefLines = true // Show reference lines

Complete Example​

const viewer = new Cesium.Viewer('cesiumContainer')

// Create viewshed area analysis tool
const viewshedArea = new DMap3D.analysis.viewshedArea(viewer, {
  fovx: 90,
  fovy: 60,
  visibleColor: '#00FF00',
  invisibleColor: '#FF0000',
  visibleColorAlpha: 0.4,
  invisibleColorAlpha: 0.4
})

// Analyze directly via coordinates
viewshedArea.setPositionAnalysis({
  startPosition: [116.4074, 39.9042, 100],
  endPosition: [116.4174, 39.9142, 50]
})

// Dynamically adjust parameters
viewshedArea.fovx = 120
viewshedArea.offsetHeading = 45

// Destroy
viewshedArea.destroy()