[Development] Define scale for usd conversion

habitat-lab/habitat/isaacsim/scene_instance_json_to_usd.py

@@ -339,17 +339,16 @@ def add_habitat_visual_to_usd_root(
     )
 
 
-def add_xform_scale(object_xform: "UsdGeom.Xform") -> None:
+def add_xform_scale(
+    obj_instance_json: Dict[str, Any], object_xform: "UsdGeom.Xform"
+) -> None:
     """Add object scale value into xform class for scene instance json.
 
     :param object_xform: The Xform class containing scene object information.
     """
     # Ensure scale op exists, default value
-    scale = [
-        1.0,
-        1.0,
-        1.0,
-    ]  # obj_instance_json.get("non_uniform_scale", [1.0, 1.0, 1.0])
+    hab_scale = obj_instance_json.get("non_uniform_scale", [1.0, 1.0, 1.0])
+    usd_scale = habitat_to_usd_scale(hab_scale)
 
     scale_op = next(
         (
@@ -361,7 +360,20 @@ def add_xform_scale(object_xform: "UsdGeom.Xform") -> None:
     )
     if scale_op is None:
         scale_op = object_xform.AddScaleOp()
-    scale_op.Set(Gf.Vec3f(*scale))
+    scale_op.Set(Gf.Vec3f(*usd_scale))
+
+
+def habitat_to_usd_scale(scale: List[float]) -> List[float]:
+    """
+    Convert a position from Habitat (Y-up) to USD (Z-up) coordinate system. Habitat (-x, z, y) -> Isaac (x, y, z)
+
+    :param position: Habitat coordinates
+    :return: Isaac coordinates
+    """
+
+    abs_scale = [abs(num) for num in scale]
+    x, y, z = abs_scale
+    return [x, z, y]
 
 
 def add_xform_rotation(
@@ -558,7 +570,7 @@ def convert_hab_scene(
 
         # Operation are performed in the order listed, change as desired
         # Current order is scale at global origin, local rotation at global origin, then translate from global origin
-        add_xform_scale(object_xform)
+        add_xform_scale(obj_instance_json, object_xform)
         add_xform_rotation(obj_instance_json, object_xform)
         add_xform_translation(obj_instance_json, object_xform)
 

test/test_isaac_sim.py

@@ -30,6 +30,16 @@
 
 
 ## Helper functions
+def usd_to_habitat_scale(scale: List[float]) -> List[float]:
+    """
+    Convert a scale from USD (Z-up) to Habitat (Y-up) coordinate system.
+
+    Issac (x, y, z) -> Habitat (x, z, y)
+    """
+    x, y, z = scale
+    return [x, z, y]
+
+
 def usd_to_habitat_position(position: List[float]) -> List[float]:
     """
     Convert a position from USD (Z-up) to Habitat (Y-up) coordinate system.
@@ -140,14 +150,15 @@ def test_example2_scene_instance():
         xform_prim.GetAttribute("xformOp:orient").Get().imaginary
     )
     usda_orient_real = xform_prim.GetAttribute("xformOp:orient").Get().real
-    # usda_scale = list(xform_prim.GetAttribute("xformOp:scale").Get())
+    usda_scale = list(xform_prim.GetAttribute("xformOp:scale").Get())
     usda_translate = list(xform_prim.GetAttribute("xformOp:translate").Get())
 
     # change usd coords back to habitat coords
 
-    usda_translate_hab_coord = usd_to_habitat_position(usda_translate)
+    hab_translate_from_usd = usd_to_habitat_position(usda_translate)
     usda_rotation = [usda_orient_real] + usda_orient_im
-    usda_rotation_hab_coord = usd_to_habitat_rotation(usda_rotation)
+    hab_rotation_from_usd = usd_to_habitat_rotation(usda_rotation)
+    hab_scale_from_usd = usd_to_habitat_scale(usda_scale)
 
     with open(scene_filepath, "r") as file:
         scene_instance_json_data = json.load(file)
@@ -158,17 +169,19 @@ def test_example2_scene_instance():
     scene_instance_rotation = scene_instance_json_data["object_instances"][0][
         "rotation"
     ]
-    # scene_instance_uniform_scale = scene_instance_json_data[
-    #     "object_instances"
-    # ][0]["non_uniform_scale"]
+    scene_instance_uniform_scale = scene_instance_json_data[
+        "object_instances"
+    ][0]["non_uniform_scale"]
+
+    abs_val_scene_instance_uniform_scale = [
+        abs(num) for num in scene_instance_uniform_scale
+    ]
 
-    assert usda_translate_hab_coord == pytest.approx(
-        scene_instance_translation
+    assert hab_translate_from_usd == pytest.approx(scene_instance_translation)
+    assert hab_rotation_from_usd == pytest.approx(scene_instance_rotation)
+    assert hab_scale_from_usd == pytest.approx(
+        abs_val_scene_instance_uniform_scale
     )
-    assert usda_rotation_hab_coord == pytest.approx(scene_instance_rotation)
-    # TODO: Add Scale to show values are equal, looks like most objects are (1, 1, 1) for the (x, y, z) coordinates in hab space.
-    # Not sure, but pxr space is has values from 0 to infinity, and 1 is default, but hab space has
-    # -1 values?  Don't know what hab space scaling is.
 
 
 ## urdf_to_usd.py unit tests