Add background_color to CameraCfg for cross-backend solid color backgrounds

Adds a new optional `background_color` attribute to `CameraCfg` that
accepts normalized RGB floats and wires through to all three renderer
backends:

- Newton: converts to ARGB uint32 and passes as `SensorTiledCamera.ClearData.clear_color`
- OV RTX: authors `omni:rtx:background:source:type = "color"` and the
  corresponding color attribute on the USD render product
- PhysX RTX (IsaacRtx): applies `/rtx/background/source/type = 2` and
  color via the settings manager

Defaults to `None` so existing behavior is preserved for all backends.

Author: mataylor-nvidia

source/isaaclab/changelog.d/mataylor-camera-background-color.minor.rst

@@ -0,0 +1,7 @@
+Added
+^^^^^
+
+* Added :attr:`~isaaclab.sensors.camera.CameraCfg.background_color` to
+  :class:`~isaaclab.sensors.camera.CameraCfg` as a unified cross-backend way to set the camera
+  background to a solid color. Accepts normalized RGB floats ``(r, g, b)`` in ``[0, 1]``;
+  defaults to ``None`` (each backend's original default background).

source/isaaclab/isaaclab/sensors/camera/camera_cfg.py

@@ -190,6 +190,17 @@ class OffsetCfg:
         on :attr:`renderer_cfg` instead.
     """
 
+    background_color: tuple[float, float, float] | None = None
+    """Background color for the camera as normalized RGB floats in ``[0, 1]``.
+
+    When set, the renderer fills pixels that miss all geometry with the given solid color.
+    When ``None`` (the default), each backend uses its own default background
+    (dome-light for RTX backends, gray for Newton).
+
+    The value is specified as ``(red, green, blue)`` with each component in ``[0, 1]``.
+    For example, ``(0.0, 0.0, 0.0)`` is black and ``(1.0, 1.0, 1.0)`` is white.
+    """
+
     renderer_cfg: RendererCfg = field(default_factory=RendererCfg)
     """Renderer configuration for camera sensor."""
 

source/isaaclab_newton/changelog.d/mataylor-camera-background-color.rst

@@ -0,0 +1,6 @@
+Added
+^^^^^
+
+* Added support for :attr:`~isaaclab.sensors.camera.CameraCfg.background_color` in
+  :class:`~isaaclab_newton.renderers.NewtonWarpRenderer`. When set, converts the normalized RGB
+  color to an ARGB clear color passed to ``SensorTiledCamera.ClearData`` on each render call.

source/isaaclab_newton/isaaclab_newton/renderers/newton_warp_renderer.py

@@ -112,6 +112,16 @@ def __init__(self, newton_sensor: newton.sensors.SensorTiledCamera, spec: Camera
         clipping_range = getattr(spawn, "clipping_range", None)
         self.near_clip: float | None = float(clipping_range[0]) if clipping_range is not None else None
         self.far_clip: float | None = float(clipping_range[1]) if clipping_range is not None else None
+
+        # ARGB clear color packed as uint32. Default is 93% gray (0xFFEEEEEE), matching the
+        # RTX renderer background and improving visibility of dark objects.
+        background_color = getattr(spec.cfg, "background_color", None)
+        if background_color is not None:
+            r, g, b = (max(0, min(255, round(c * 255))) for c in background_color)
+            self.clear_color: int = (0xFF << 24) | (r << 16) | (g << 8) | b
+        else:
+            self.clear_color = 0xFFEEEEEE
+
         # Post-render PPISP pipeline composed when ``spec.cfg.isp_cfg`` is set.
         # ``isp_cfg`` is already fully normalized by ``prepare_cameras`` by the time it reaches here.
         self.ppisp_pipeline: PpispPipeline | None = None
@@ -471,9 +481,8 @@ def render(self, render_data: RenderData):
             depth_image=render_data.outputs.depth_image,
             normal_image=render_data.outputs.normals_image,
             shape_index_image=render_data.outputs.instance_segmentation_image,
-            # ARGB 93% gray to improve visibility of dark objects and align with RTX renderer background
             clear_data=newton.sensors.SensorTiledCamera.ClearData(
-                clear_color=0xFFEEEEEE,
+                clear_color=render_data.clear_color,
                 **({"clear_depth": render_data.far_clip} if _use_depth_clear else {}),
             ),
             kernel_block_dim=self.cfg.kernel_block_dim,

source/isaaclab_ov/changelog.d/mataylor-camera-background-color.rst

@@ -0,0 +1,7 @@
+Added
+^^^^^
+
+* Added support for :attr:`~isaaclab.sensors.camera.CameraCfg.background_color` in
+  :class:`~isaaclab_ov.renderers.OVRTXRenderer`. When set, authors
+  ``omni:rtx:background:source:type = "color"`` and ``omni:rtx:background:source:color`` on the
+  USD render product instead of the default ``"domeLight"`` background.

source/isaaclab_ov/isaaclab_ov/renderers/ovrtx_renderer.py

@@ -405,6 +405,7 @@ def _initialize_from_spec(self, spec: CameraRenderSpec):
             data_types=data_types,
             minimal_mode=_resolve_rtx_minimal_mode(data_types),
             camera_rel_path=self._camera_rel_path,
+            background_color=getattr(spec.cfg, "background_color", None),
         )
         self._render_product_paths.append(render_product_path)
 

source/isaaclab_ov/isaaclab_ov/renderers/ovrtx_usd.py

@@ -105,6 +105,7 @@ def build_render_scope_usd(
     tiled_height: int,
     minimal_mode: int | None = None,
     render_var_configs: list[tuple[str, str, str]] | None = None,
+    background_color: tuple[float, float, float] | None = None,
 ) -> str:
     """Build the Render scope USD string (def Scope Render, RenderProduct, Vars).
 
@@ -118,6 +119,9 @@ def build_render_scope_usd(
         tiled_height: Height of the tiled image.
         minimal_mode: RTX minimal mode. None if not requested. Valid values are 1, 2, 3.
         render_var_configs: Render variables to author. Uses the single render var arguments if not provided.
+        background_color: Solid background color as normalized RGB floats ``(r, g, b)`` in ``[0, 1]``.
+            When set, the render product uses ``"color"`` as the background source type.
+            When ``None``, the default ``"domeLight"`` background is used.
 
     Returns:
         The USD string for the render scope.
@@ -144,14 +148,24 @@ def build_render_scope_usd(
         for _, name, source in render_var_configs
     )
 
+    if background_color is not None:
+        r, g, b = background_color
+        background_lines = (
+            f'token omni:rtx:background:source:type = "color"\n'
+            f"        float3 omni:rtx:background:source:color = ({r}, {g}, {b})"
+        )
+    else:
+        # Do not set background source type
+        background_lines = ""
+
     return f'''
 def Scope "Render"
 {{
     def RenderProduct "{render_product_name}" (
         prepend apiSchemas = ["OmniRtxSettingsCommonAdvancedAPI_1"]
     ) {{
         rel camera = [{camera_rel_list}]
-        token omni:rtx:background:source:type = "domeLight"
+        {background_lines}
         float omni:rtx:rt:ambientLight:intensity = 1.0
         {render_mode_block}
         token[] omni:rtx:waitForEvents = ["AllLoadingFinished", "OnlyOnFirstRequest"]
@@ -181,6 +195,7 @@ def build_render_product_as_string(
     data_types: list[str],
     minimal_mode: int | None = None,
     camera_rel_path: str = "Camera",
+    background_color: tuple[float, float, float] | None = None,
 ) -> tuple[str, str]:
     """Build the render product USD snippet as a string.
 
@@ -193,6 +208,9 @@ def build_render_product_as_string(
         data_types: Data types from sensor config.
         minimal_mode: RTX minimal mode. None if not requested. Valid values are 1, 2, 3.
         camera_rel_path: Camera prim path relative to the env root (e.g. ``"Camera"`` or ``"Robot/head_cam"``).
+        background_color: Solid background color as normalized RGB floats ``(r, g, b)`` in ``[0, 1]``.
+            When set, the render product uses a solid color background instead of the dome light.
+            When ``None``, the default dome-light background is used.
 
     Returns:
         Tuple of (render product USD snippet as a string, absolute render product prim path).
@@ -217,6 +235,7 @@ def build_render_product_as_string(
         tiled_height,
         minimal_mode,
         render_var_configs,
+        background_color,
     )
     return camera_content, render_product_path
 

source/isaaclab_ov/test/test_ovrtx_usd.py

@@ -76,6 +76,38 @@ def _assert_export_omits_env_children(exported: str, env_indices: range | list[i
         assert f'def Xform "Object_env{env_idx}_only"' not in exported
 
 
+def test_build_render_scope_usd_default_background_is_dome_light():
+    """Default background (background_color=None) uses domeLight source type."""
+    render_scope = build_render_scope_usd(
+        camera_paths=["/World/envs/env_0/Camera"],
+        render_product_name="RenderProduct",
+        render_var_path="/Render/Vars/LdrColor",
+        render_var_name="LdrColor",
+        source_name="LdrColor",
+        tiled_width=16,
+        tiled_height=8,
+    )
+    assert 'token omni:rtx:background:source:type = "domeLight"' in render_scope
+    assert "omni:rtx:background:source:color" not in render_scope
+
+
+def test_build_render_scope_usd_solid_background_color():
+    """Providing background_color emits color source type and the color attribute."""
+    render_scope = build_render_scope_usd(
+        camera_paths=["/World/envs/env_0/Camera"],
+        render_product_name="RenderProduct",
+        render_var_path="/Render/Vars/LdrColor",
+        render_var_name="LdrColor",
+        source_name="LdrColor",
+        tiled_width=16,
+        tiled_height=8,
+        background_color=(1.0, 0.0, 0.5),
+    )
+    assert 'token omni:rtx:background:source:type = "color"' in render_scope
+    assert "float3 omni:rtx:background:source:color = (1.0, 0.0, 0.5)" in render_scope
+    assert 'token omni:rtx:background:source:type = "domeLight"' not in render_scope
+
+
 def test_ovrtx_rgb_hdr_uses_hdr_color_render_var():
     """Requesting RGB_HDR from OVRTX selects the HdrColor render variable."""
     assert get_render_var_config(["rgb_hdr"]) == ("/Render/Vars/HdrColor", "HdrColor", "HdrColor")

source/isaaclab_physx/changelog.d/mataylor-camera-background-color.rst

@@ -0,0 +1,7 @@
+Added
+^^^^^
+
+* Added support for :attr:`~isaaclab.sensors.camera.CameraCfg.background_color` in
+  :class:`~isaaclab_physx.renderers.IsaacRtxRenderer`. When set, applies
+  ``/rtx/background/source/type = 2`` (Color) and ``/rtx/background/source/color`` via the
+  settings manager during camera setup.

source/isaaclab_physx/isaaclab_physx/renderers/isaac_rtx_renderer.py

@@ -142,7 +142,18 @@ def prepare_cameras(self, stage: Any, spec: CameraRenderSpec) -> None:
         ``exposure:*`` to neutral and applies ``OmniRtxCameraExposureAPI_1`` so
         RTX's physical-camera exposure model does not compound on top of the
         ISP. Without an ISP, the camera prim's authored exposure is left alone.
+
+        When :attr:`~isaaclab.sensors.camera.CameraCfg.background_color` is set,
+        applies the two RTX carb settings that switch the background to a solid color:
+        ``/rtx/background/source/type = 2`` and ``/rtx/background/source/color``.
         """
+        background_color = getattr(spec.cfg, "background_color", None)
+        if background_color is not None:
+            settings = get_settings_manager()
+            r, g, b = background_color
+            settings.set("/rtx/background/source/type", 2)
+            settings.set("/rtx/background/source/color", (r, g, b))
+
         if spec.cfg.isp_cfg is None:
             return
         try: