增加坡度计算

slope/slope_aspect.py

@@ -0,0 +1,83 @@
+import xdem
+import rasterio
+import numpy as np
+
+def calc_cosine_i(solar_zn, solar_az, aspect, slope):
+    """Generate cosine i image. The cosine of the incidence angle (i) is
+       defined as the angle between the normal to the pixel surface
+       and the solar zenith direction.
+       All input geometry units must be in radians.
+
+    Args:
+        solar_az (numpy.ndarray): Solar azimuth angle.
+        solar_zn (numpy.ndarray): Solar zenith angle.
+        aspect (numpy.ndarray): Ground aspect.
+        slope (numpy.ndarray): Ground slope.
+
+    Returns:
+        numpy.ndarray: Cosine i image.
+    """
+    relative_az = aspect - solar_az
+    cosine_i = (np.cos(solar_zn) * np.cos(slope) +
+                np.sin(solar_zn) * np.sin(slope) * np.cos(relative_az))
+    return cosine_i
+
+# ========== 1. 读取 DEM ==========
+dem = xdem.DEM("E:/is2/yaopu/DEM/dsm.tif")
+
+# ========== 2. 计算坡度、坡向 ==========
+slope = xdem.terrain.slope(dem, method='ZevenbergThorne')
+aspect = xdem.terrain.aspect(dem)
+
+# ========== 3. 获取空间参考信息 ==========
+transform = dem.transform
+crs = dem.crs
+
+# ========== 4. 转换为 numpy 数组 ==========
+slope_data = slope.data
+aspect_data = aspect.data
+
+# ========== 5. 太阳角度（单位：度，根据实际飞行时间和地理位置设置） ==========
+solar_zn_deg = 30.0   # 太阳天顶角（从天顶到太阳的夹角），例如 30°
+solar_az_deg = 180.0  # 太阳方位角（从北顺时针），例如 180°（正南）
+
+# 转换为弧度（因为三角函数需要弧度）
+solar_zn_rad = np.deg2rad(solar_zn_deg)
+solar_az_rad = np.deg2rad(solar_az_deg)
+
+# 坡度和坡向也转换为弧度
+slope_rad = np.deg2rad(slope_data)
+aspect_rad = np.deg2rad(aspect_data)
+
+# ========== 6. 计算 cosine_i ==========
+cosine_i = calc_cosine_i(solar_zn_rad, solar_az_rad, aspect_rad, slope_rad)
+
+# ========== 7. 处理无效值（NaN） ==========
+# 注意：将 NaN 替换为 0 可能会与真实值为 0 的像元混淆（如水平面坡度为0，阴影边缘cosine_i=0）。
+# 如需严格区分，建议使用特殊值（如 -9999）作为 NoData。
+slope_data = np.nan_to_num(slope_data, nan=0.0)
+aspect_data = np.nan_to_num(aspect_data, nan=0.0)
+cosine_i = np.nan_to_num(cosine_i, nan=0.0)
+
+# ========== 8. 堆叠为多波段数组（坡度、坡向、cosine_i） ==========
+stacked = np.stack([slope_data, aspect_data, cosine_i], axis=0)
+
+# ========== 9. 输出 ENVI 格式文件 ==========
+output_path = "E:/is2/yaopu/DEM/slope_aspect_cosine.dat"
+
+with rasterio.open(
+    output_path,
+    'w',
+    driver='ENVI',
+    height=stacked.shape[1],
+    width=stacked.shape[2],
+    count=stacked.shape[0],
+    dtype=stacked.dtype,
+    crs=crs,
+    transform=transform,
+    nodata=0.0,           # 与上面替换的 NaN 值一致
+) as dst:
+    dst.write(stacked)
+
+print(f"已保存多波段 ENVI 文件：{output_path}")
+print(f"波段顺序：1-坡度(°), 2-坡向(°), 3-cosine_i")