Fixes terrain origin computing in the inverted pyramid slope terrain

CONTRIBUTORS.md

@@ -145,6 +145,7 @@ Guidelines for modifications:
 * Xavier Nal
 * Xinjie Yao
 * Xinpeng Liu
+* Xin Xu
 * Yang Jin
 * Yanzi Zhu
 * Yijie Guo

source/isaaclab/isaaclab/terrains/height_field/hf_terrains.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2022-2025, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
 # All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
@@ -11,7 +11,7 @@
 import scipy.interpolate as interpolate
 from typing import TYPE_CHECKING
 
-from .utils import height_field_to_mesh
+from .utils import height_field_to_mesh, height_field_to_mesh_v2
 
 if TYPE_CHECKING:
     from . import hf_terrains_cfg
@@ -79,7 +79,7 @@ def random_uniform_terrain(difficulty: float, cfg: hf_terrains_cfg.HfRandomUnifo
     return np.rint(z_upsampled).astype(np.int16)
 
 
-@height_field_to_mesh
+@height_field_to_mesh_v2(terrain_origin_judge_width=1.0)
 def pyramid_sloped_terrain(difficulty: float, cfg: hf_terrains_cfg.HfPyramidSlopedTerrainCfg) -> np.ndarray:
     """Generate a terrain with a truncated pyramid structure.
 

source/isaaclab/isaaclab/terrains/height_field/utils.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2022-2025, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
 # All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
@@ -76,6 +76,59 @@ def wrapper(difficulty: float, cfg: HfTerrainBaseCfg):
     return wrapper
 
 
+def height_field_to_mesh_v2(terrain_origin_judge_width: float = 2.0):
+    """
+    the terrain origin is computed as the max in the square area around the center of the terrain,
+    the square width is `terrain_origin_judge_width`
+    """
+
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(difficulty: float, cfg: HfTerrainBaseCfg):
+            # check valid border width
+            if cfg.border_width > 0 and cfg.border_width < cfg.horizontal_scale:
+                raise ValueError(
+                    f"The border width ({cfg.border_width}) must be greater than or equal to the"
+                    f" horizontal scale ({cfg.horizontal_scale})."
+                )
+            # allocate buffer for height field (with border)
+            width_pixels = int(cfg.size[0] / cfg.horizontal_scale) + 1
+            length_pixels = int(cfg.size[1] / cfg.horizontal_scale) + 1
+            border_pixels = int(cfg.border_width / cfg.horizontal_scale) + 1
+            heights = np.zeros((width_pixels, length_pixels), dtype=np.int16)
+            # override size of the terrain to account for the border
+            sub_terrain_size = [width_pixels - 2 * border_pixels, length_pixels - 2 * border_pixels]
+            sub_terrain_size = [dim * cfg.horizontal_scale for dim in sub_terrain_size]
+            # update the config
+            terrain_size = copy.deepcopy(cfg.size)
+            cfg.size = tuple(sub_terrain_size)
+            # generate the height field
+            z_gen = func(difficulty, cfg)
+            # handle the border for the terrain
+            heights[border_pixels:-border_pixels, border_pixels:-border_pixels] = z_gen
+            # set terrain size back to config
+            cfg.size = terrain_size
+
+            # convert to trimesh
+            vertices, triangles = convert_height_field_to_mesh(
+                heights, cfg.horizontal_scale, cfg.vertical_scale, cfg.slope_threshold
+            )
+            mesh = trimesh.Trimesh(vertices=vertices, faces=triangles)
+            # compute origin
+            x1 = int((cfg.size[0] * 0.5 - terrain_origin_judge_width / 2.0) / cfg.horizontal_scale)
+            x2 = int((cfg.size[0] * 0.5 + terrain_origin_judge_width / 2.0) / cfg.horizontal_scale)
+            y1 = int((cfg.size[1] * 0.5 - terrain_origin_judge_width / 2.0) / cfg.horizontal_scale)
+            y2 = int((cfg.size[1] * 0.5 + terrain_origin_judge_width / 2.0) / cfg.horizontal_scale)
+            origin_z = np.max(heights[x1:x2, y1:y2]) * cfg.vertical_scale
+            origin = np.array([0.5 * cfg.size[0], 0.5 * cfg.size[1], origin_z])
+            # return mesh and origin
+            return [mesh], origin
+
+        return wrapper
+
+    return decorator
+
+
 def convert_height_field_to_mesh(
     height_field: np.ndarray, horizontal_scale: float, vertical_scale: float, slope_threshold: float | None = None
 ) -> tuple[np.ndarray, np.ndarray]: