畫面中呈現逼真的淺色虛擬物體

瞭解如何在自己的應用程式中使用亮度估算功能。

必要條件

請務必先瞭解基本 AR 概念，以及如何設定 ARCore 工作階段，然後再繼續操作。

以適當模式為每個工作階段設定一次 API

針對您要使用的模式，為每個工作階段設定一次亮度預估功能。

Java

// Configure the session with the Lighting Estimation API in ENVIRONMENTAL_HDR mode.
Config config = session.getConfig();
config.setLightEstimationMode(LightEstimationMode.ENVIRONMENTAL_HDR);
session.configure(config);

// Configure the session with the Lighting Estimation API in AMBIENT_INTENSITY mode.
Config config = session.getConfig();
config.setLightEstimationMode(LightEstimationMode.AMBIENT_INTENSITY);
session.configure(config);

// Configure the session with the Lighting Estimation API turned off.
Config config = session.getConfig();
config.setLightEstimationMode(LightEstimationMode.DISABLED);
session.configure(config);

Kotlin

// Configure the session with the Lighting Estimation API in ENVIRONMENTAL_HDR mode.
Config config = session.config
config.lightEstimationMode = LightEstimationMode.ENVIRONMENTAL_HDR
session.configure(config)

// Configure the session with the Lighting Estimation API in AMBIENT_INTENSITY mode.
Config config = session.config
config.lightEstimationMode = LightEstimationMode.AMBIENT_INTENSITY
session.configure(config)

// Configure the session with the Lighting Estimation API turned off.
Config config = session.config
config.lightEstimationMode = LightEstimationMode.DISABLED
session.configure(config)

設定ENVIRONMENTAL_HDR模式

如要設定 ENVIRONMENTAL_HDR 模式，請取得每個影格的光學資料，然後取得要使用的環境 HDR 照明元件。

Java

void update() {
  // Get the current frame.
  Frame frame = session.update();

  // Get the light estimate for the current frame.
  LightEstimate lightEstimate = frame.getLightEstimate();

  // Get intensity and direction of the main directional light from the current light estimate.
  float[] intensity = lightEstimate.getEnvironmentalHdrMainLightIntensity(); // note - currently only out param.
  float[] direction = lightEstimate.getEnvironmentalHdrMainLightDirection();
  app.setDirectionalLightValues(intensity, direction); // app-specific code.

  // Get ambient lighting as spherical harmonics coefficients.
  float[] harmonics = lightEstimate.getEnvironmentalHdrAmbientSphericalHarmonics();
  app.setAmbientSphericalHarmonicsLightValues(harmonics); // app-specific code.

  // Get HDR environmental lighting as a cubemap in linear color space.
  Image[] lightmaps = lightEstimate.acquireEnvironmentalHdrCubeMap();
  for (int i = 0; i < lightmaps.length /*should be 6*/; ++i) {
    app.uploadToTexture(i, lightmaps[i]);  // app-specific code.
  }
}

Kotlin

fun update() {
  // Get the current frame.
  val frame = session.update()

  // Get the light estimate for the current frame.
  val lightEstimate = frame.lightEstimate

  // Get intensity and direction of the main directional light from the current light estimate.
  val intensity = lightEstimate.environmentalHdrMainLightIntensity
  val direction = lightEstimate.environmentalHdrMainLightDirection
  app.setDirectionalLightValues(intensity, direction) // app-specific code.

  // Get ambient lighting as spherical harmonics coefficients.
  val harmonics = lightEstimate.environmentalHdrAmbientSphericalHarmonics
  app.ambientSphericalHarmonicsLightValues = harmonics // app-specific code.

  // Get HDR environmental lighting as a cubemap in linear color space.
  val lightMaps = lightEstimate.acquireEnvironmentalHdrCubeMap();
  for ((index, lightMap) in lightMaps.withIndex()) { // 6 maps total.
    app.uploadToTexture(index, lightMap); // app-specific code.
  }
}

設定AMBIENT_INTENSITY模式

如果您打算使用 AMBIENT_INTENSITY 模式的色彩校正元件，請先重複使用共用的配置，避免在每個影格上配置色彩校正。

Java

 // Avoid allocation on every frame.
float[] colorCorrection = new float[4];

Kotlin

val colorCorrection = floatArrayOf(0.0f, 0.0f, 0.0f, 0.0f)

取得每個影格的光度預估值，然後取得要使用的環境強度元件。

Java

void update() {
  // Get the current frame.
  Frame frame = session.update();

  // Get the light estimate for the current frame.
  LightEstimate lightEstimate = frame.getLightEstimate();

  // Get the pixel intensity of AMBIENT_INTENSITY mode.
  float pixelIntensity = lightEstimate.getPixelIntensity();

  // Read the pixel color correction of AMBIENT_INTENSITY mode into colorCorrection.
  lightEstimate.getColorCorrection(colorCorrection, 0);
}

Kotlin

fun update() {
    // Get the current frame.
  val frame = session.update()

  // Get the light estimate for the current frame.
  val lightEstimate = frame.lightEstimate

  // Get the pixel intensity of AMBIENT_INTENSITY mode.
  val pixelIntensity = lightEstimate.pixelIntensity

  // Read the pixel color correction of AMBIENT_INTENSITY mode into colorCorrection.
  lightEstimate.getColorCorrection(colorCorrection, 0)
}

運用環境 HDR API 確保節能

能源保育原則上，從表面反射的光線絕對不會比表面上反射出的光線更強。系統會在實體式轉譯時強制執行這項規則，但電玩遊戲和行動應用程式中使用的舊版算繪管道通常會省略這項規則。

如果您使用實體式轉譯管道搭配環境 HDR 光預估，只要在虛擬物件中使用以實體為基礎的材料即可。

如果您並未使用以實體為基礎的管道，有以下兩種做法：

  • 最理想的解決方案是遷移至實體式管道。

  • 不過，如果無法這麼做，理想的解決方法是將非實體物質的代數值乘以節能因子。這樣就能確保至少將 BRDF 陰影模型轉換為實體型。每個 BRDF 都有不同的因素，例如，擴散反射反射率則為 1/Pi。