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ee.Algorithms.TemporalSegmentation.Ewmacd
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指数加权移动平均值变化检测。此算法会针对输入数据的“训练”部分计算谐波模型,并从原始结果中减去该模型。然后,对残差进行休哈特 X-bar 图表分析和指数加权移动平均分析。当图表显示超出指定控制限度的偏差时,系统会指示异常像素。
输出是一张包含以下波段的 5 波段图片:
ewma:一个 1 维数组,包含每个输入图片的 EWMA 得分。负值表示干扰,正值表示恢复。
harmonicCoefficients:一个 1 维数组,包含计算出的谐波系数组。系数的顺序为 [constant, sin0, cos0, sin1, cos1...]
rmse:谐波回归的 RMSE。
rSquared:谐波回归的 R 平方值。
残差:谐波回归的 1 维残差数组。
参见:Brooks, E.B.、Wynne, R.H.、Thomas, V.A.、Blinn, C.E. 和 Coulston, J.W.,2014 年。使用统计质量控制图和 Landsat 数据进行大规模多时相实时变化检测。IEEE Transactions on Geoscience and Remote Sensing,52(6),第 3316-3332 页。
用法 | 返回 |
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ee.Algorithms.TemporalSegmentation.Ewmacd(timeSeries, vegetationThreshold, trainingStartYear, trainingEndYear, harmonicCount, xBarLimit1, xBarLimit2, lambda, lambdasigs, rounding, persistence) | 图片 |
参数 | 类型 | 详细信息 |
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timeSeries | ImageCollection | 从中提取 EWMA 的集合。此集合应包含每个年份的 1 张图片,并按时间顺序排序。 |
vegetationThreshold | 浮点数 | 植被阈值。低于此值的值会被视为非植被。 |
trainingStartYear | 整数 | 训练时段的开始年份(含)。 |
trainingEndYear | 整数 | 培训期的结束年份(不含)。 |
harmonicCount | 整数,默认值:2 | 所使用的谐波函数对(正弦和余弦)的数量。 |
xBarLimit1 | 浮点数,默认值:1.5 | 初始训练 xBar 限制的阈值。 |
xBarLimit2 | 整数,默认值:20 | 运行 xBar 限制的阈值。 |
lambda | 浮点数,默认值:0.3 | “lambda”调整形参,用于确定新年份与滚动平均值的权重。 |
lambdasigs | 浮点数,默认值:3 | EWMA 控制界限,以标准差为单位。 |
rounding | 布尔值,默认值:true | 是否应针对 EWMA 执行舍入。 |
persistence | 整数,默认值:3 | 考虑变化所需的最少观测次数。 |
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最后更新时间 (UTC):2025-07-27。
[null,null,["最后更新时间 (UTC):2025-07-27。"],[[["\u003cp\u003eExponentially Weighted Moving Average Change Detection (EWMACD) identifies disturbed pixels by comparing image data to a harmonic model and analyzing residuals using control charts.\u003c/p\u003e\n"],["\u003cp\u003eEWMACD uses a training period to establish a baseline and then monitors deviations from this baseline in subsequent years.\u003c/p\u003e\n"],["\u003cp\u003eThe output includes an EWMA score indicating disturbance (negative values) or recovery (positive values), harmonic coefficients, RMSE, r-squared, and residuals.\u003c/p\u003e\n"],["\u003cp\u003eUsers can customize parameters such as the training period, harmonic count, control limits, and persistence for change detection.\u003c/p\u003e\n"],["\u003cp\u003eThe algorithm is designed for analyzing multitemporal image collections, particularly for vegetation change detection using thresholds.\u003c/p\u003e\n"]]],[],null,["# ee.Algorithms.TemporalSegmentation.Ewmacd\n\nExponentially Weighted Moving Average Change Detection. This algorithm computes a harmonic model for the 'training' portion of the input data and subtracts that from the original results. The residuals are then subjected to Shewhart X-bar charts and an exponentially weighted moving average. Disturbed pixels are indicated when the charts signal a deviation from the given control limits.\n\n\u003cbr /\u003e\n\nThe output is a 5 band image containing the bands:\n\newma: a 1D array of the EWMA score for each input image. Negative values represent disturbance and positive values represent recovery.\n\nharmonicCoefficients: A 1-D array of the computed harmonic coefficient pairs. The coefficients are ordered as \\[constant, sin0, cos0, sin1, cos1...\\]\n\nrmse: the RMSE from the harmonic regression.\n\nrSquared: r-squared value from the harmonic regression.\n\nresiduals: 1D array of residuals from the harmonic regression.\n\nSee: Brooks, E.B., Wynne, R.H., Thomas, V.A., Blinn, C.E. and Coulston, J.W., 2014. On-the-fly massively multitemporal change detection using statistical quality control charts and Landsat data. IEEE Transactions on Geoscience and Remote Sensing, 52(6), pp.3316-3332.\n\n| Usage | Returns |\n|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|\n| `ee.Algorithms.TemporalSegmentation.Ewmacd(timeSeries, vegetationThreshold, trainingStartYear, trainingEndYear, `*harmonicCount* `, `*xBarLimit1* `, `*xBarLimit2* `, `*lambda* `, `*lambdasigs* `, `*rounding* `, `*persistence*`)` | Image |\n\n| Argument | Type | Details |\n|-----------------------|------------------------|-------------------------------------------------------------------------------------------------------------------------------|\n| `timeSeries` | ImageCollection | Collection from which to extract EWMA. This collection is expected to contain 1 image for each year and be sorted temporally. |\n| `vegetationThreshold` | Float | Threshold for vegetation. Values below this are considered non-vegetation. |\n| `trainingStartYear` | Integer | Start year of training period, inclusive. |\n| `trainingEndYear` | Integer | End year of training period, exclusive. |\n| `harmonicCount` | Integer, default: 2 | Number of harmonic function pairs (sine and cosine) used. |\n| `xBarLimit1` | Float, default: 1.5 | Threshold for initial training xBar limit. |\n| `xBarLimit2` | Integer, default: 20 | Threshold for running xBar limit. |\n| `lambda` | Float, default: 0.3 | The 'lambda' tuning parameter weighting new years vs the running average. |\n| `lambdasigs` | Float, default: 3 | EWMA control bounds, in units of standard deviations. |\n| `rounding` | Boolean, default: true | Should rounding be performed for EWMA. |\n| `persistence` | Integer, default: 3 | Minimum number of observations needed to consider a change. |"]]