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Tileset Flattening Analysis

DMap3D.analysis.flattenAnalysis is used to flatten specified regions on 3D Tiles models.

Import​

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

Basic Usage​

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

// Load 3D Tiles model
const tileset = await Cesium.Cesium3DTileset.fromUrl('/path/to/tileset.json')
viewer.scene.primitives.add(tileset)

// Create flattening tool
const flatten = new DMap3D.analysis.flattenAnalysis(viewer)

// Activate flattening (left-click to draw polygon, right-click to finish)
flatten.activate(tileset)

Constructor​

new DMap3D.analysis.flattenAnalysis(viewer)​

Parameters:

  • viewer - Cesium.Viewer instance

Methods​

activate(tileset, height?)​

Activate drawing and apply flattening. The user left-clicks to add polygon vertices, and right-clicks to finish drawing and automatically apply the flattening effect.

// Flatten to polygon center height
flatten.activate(tileset)

// Flatten to specified height (relative to polygon center, in meters)
flatten.activate(tileset, -5.0) // Flatten to 5 meters below center
flatten.activate(tileset, 10.0) // Flatten to 10 meters above center

Parameters:

  • tileset - Cesium.Cesium3DTileset instance
  • height? - Flattening height (optional), default 0 (polygon center height)

setHeight(height)​

Dynamically update the flattening height.

flatten.setHeight(-10.0) // Adjust flattening height

clear()​

Clear the flattening effect and restore the original model state.

flatten.clear()

destroy()​

Destroy the tool and release resources.

flatten.destroy()

Complete Example​

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

// Load 3D Tiles
const tileset = await Cesium.Cesium3DTileset.fromUrl('/3DTiles/DaYanTa/tileset.json')
viewer.scene.primitives.add(tileset)
await viewer.zoomTo(tileset)

// Create flattening tool
const flatten = new DMap3D.analysis.flattenAnalysis(viewer)

// Activate flattening
flatten.activate(tileset, 0)

// Dynamically adjust height
flatten.setHeight(-5.0)

// Clear flattening
flatten.clear()

// Re-flatten to a different height
flatten.activate(tileset, 10.0)

// Destroy
flatten.destroy()

Technical Principle​

  • Uses CustomShader to modify model vertex heights in the vertex shader
  • Precisely controls the flattening region through a texture mask
  • Based on ENU local coordinate system to ensure the flattening direction is perpendicular to the ground