Merge pull request #39 from mlouielu/fix-preview-without-valid-path

Fix preview without valid path raise ValueError

Author: merlinND

src/sionna/rt/preview.py

@@ -388,8 +388,9 @@ def plot_paths(self, paths, line_width=1.0):
                     ends.append(tgt_positions[rx])
                     colors.append(color)
 
-        self._plot_lines(np.vstack(starts), np.vstack(ends),
-                         np.vstack(colors), line_width)
+        if starts:
+            self._plot_lines(np.vstack(starts), np.vstack(ends),
+                             np.vstack(colors), line_width)
         self._add_legend(category="paths")
 
     def plot_planar_radio_map(self, radio_map, tx=0, db_scale=True,

test/unit/test_preview.py

@@ -0,0 +1,85 @@
+#
+# SPDX-FileCopyrightText: Copyright (c) 2021-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+
+import drjit as dr
+import mitsuba as mi
+
+import sionna.rt as rt
+from sionna.rt.radio_materials.itu import itu_material
+from sionna.rt.scene import Scene, load_scene
+from sionna.rt import PathSolver
+
+
+def add_example_radio_devices(scene: Scene):
+    # Note: hardcoded for `box_two_screens.xml` as an example.
+    scene.add(rt.Transmitter("tr-1", position=[-3.0, 0.0, 1.5]))
+    scene.add(rt.Receiver("rc-1", position=[3.0, 0.0, 1.5]))
+    scene.add(
+        rt.Receiver(
+            "rc-2", position=[1.0, -2.0, 3.5], color=(0.9, 0.9, 0.2), display_radius=0.9
+        )
+    )
+
+    scene.rx_array = rt.PlanarArray(
+        num_rows=1, num_cols=1, pattern="tr38901", polarization="VH"
+    )
+    scene.tx_array = rt.PlanarArray(
+        num_rows=1, num_cols=1, pattern="tr38901", polarization="VH"
+    )
+
+
+def get_example_paths(scene: Scene):
+    # Ray tracing parameters
+    num_samples_per_src = int(1e6)
+    max_num_paths = int(1e7)
+    max_depth = 3
+
+    solver = PathSolver()
+    paths = solver(
+        scene,
+        max_depth=max_depth,
+        max_num_paths_per_src=max_num_paths,
+        samples_per_src=num_samples_per_src,
+    )
+
+    return paths
+
+
+def test01_preview_with_paths():
+    scene = load_scene(rt.scene.box_two_screens)
+
+    eta_r, sigma = itu_material("metal", 3e9)  # ITU material evaluated at 3GHz
+    for sh in scene.mi_scene.shapes():
+        material = sh.bsdf()
+        material.relative_permittivity = eta_r
+        material.conductivity = sigma
+        material.scattering_coefficient = 0.01
+        material.xpd_coefficient = 0.2
+
+    add_example_radio_devices(scene)
+    paths = get_example_paths(scene)
+
+    scene.preview(paths=paths)
+
+
+def test02_preview_with_paths_but_no_valid_path():
+    scene = load_scene(rt.scene.box_two_screens)
+
+    eta_r, sigma = itu_material("metal", 3e9)  # ITU material evaluated at 3GHz
+    for sh in scene.mi_scene.shapes():
+        material = sh.bsdf()
+        material.relative_permittivity = eta_r
+        material.conductivity = sigma
+        material.scattering_coefficient = 0.01
+        material.xpd_coefficient = 0.2
+
+    add_example_radio_devices(scene)
+    paths = get_example_paths(scene)
+
+    # No valid path
+    paths._valid = dr.zeros(mi.TensorXb, paths.valid.shape)
+
+    # Should not raise ValueError: need at least one array to concatenate
+    scene.preview(paths=paths)