Take units (m or mm) into account when showing fieldmaps on top of brains (#13101)

Co-authored-by: Eric Larson <larson.eric.d@gmail.com>

Author: wmvanvliet

azure-pipelines.yml

@@ -89,6 +89,7 @@ stages:
           DISPLAY: ':99'
           OPENBLAS_NUM_THREADS: '1'
           MNE_TEST_ALLOW_SKIP: '^.*(PySide6 causes segfaults).*$'
+          MNE_BROWSER_PRECOMPUTE: 'false'
         steps:
           - bash: |
               set -e

doc/changes/devel/13101.bugfix.rst

@@ -0,0 +1 @@
+Take units (m or mm) into account when drawing :func:`~mne.viz.plot_evoked_field` on top of :class:`~mne.viz.Brain`, by `Marijn van Vliet`_.

mne/conftest.py

@@ -6,6 +6,7 @@
 import inspect
 import os
 import os.path as op
+import platform
 import re
 import shutil
 import sys
@@ -190,6 +191,8 @@ def pytest_configure(config: pytest.Config):
     ignore:Starting field name with a underscore.*:
     # joblib
     ignore:process .* is multi-threaded, use of fork/exec.*:DeprecationWarning
+    # sklearn
+    ignore:Python binding for RankQuantileOptions.*:RuntimeWarning
     """  # noqa: E501
     for warning_line in warning_lines.split("\n"):
         warning_line = warning_line.strip()
@@ -285,9 +288,10 @@ def __init__(self, exception_handler=None, signals=None):
 @pytest.fixture(scope="session")
 def azure_windows():
     """Determine if running on Azure Windows."""
-    return os.getenv(
-        "AZURE_CI_WINDOWS", "false"
-    ).lower() == "true" and sys.platform.startswith("win")
+    return (
+        os.getenv("AZURE_CI_WINDOWS", "false").lower() == "true"
+        and platform.system() == "Windows"
+    )
 
 
 @pytest.fixture(scope="function")

mne/viz/evoked_field.py

@@ -7,6 +7,7 @@
 # License: BSD-3-Clause
 # Copyright the MNE-Python contributors.
 
+from copy import deepcopy
 from functools import partial
 
 import numpy as np
@@ -185,6 +186,7 @@ def __init__(
         if isinstance(fig, Brain):
             self._renderer = fig._renderer
             self._in_brain_figure = True
+            self._units = fig._units
             if _get_3d_backend() == "notebook":
                 raise NotImplementedError(
                     "Plotting on top of an existing Brain figure "
@@ -195,6 +197,7 @@ def __init__(
                 fig, bgcolor=(0.0, 0.0, 0.0), size=(600, 600)
             )
             self._in_brain_figure = False
+            self._units = "m"
 
         self.plotter = self._renderer.plotter
         self.interaction = interaction
@@ -277,7 +280,8 @@ def _prepare_surf_map(self, surf_map, color, alpha):
 
         # Make a solid surface
         surf = surf_map["surf"]
-        if self._in_brain_figure:
+        if self._units == "mm":
+            surf = deepcopy(surf)
             surf["rr"] *= 1000
         map_vmax = self._vmax.get(surf_map["kind"])
         if map_vmax is None:

mne/viz/tests/test_3d.py

@@ -191,10 +191,21 @@ def test_plot_evoked_field(renderer):
                 ch_type=t,
             )
         evoked.plot_field(maps, time=0.1, n_contours=n_contours)
+    renderer.backend._close_all()
 
-    # Test plotting inside an existing Brain figure.
-    brain = Brain("fsaverage", "lh", "inflated", subjects_dir=subjects_dir)
-    fig = evoked.plot_field(maps, time=0.1, fig=brain)
+    # Test plotting inside an existing Brain figure. Check that units are taken into
+    # account.
+    for units in ["mm", "m"]:
+        brain = Brain(
+            "fsaverage", "lh", "inflated", units=units, subjects_dir=subjects_dir
+        )
+        fig = evoked.plot_field(maps, time=0.1, fig=brain)
+        assert brain._units == fig._units
+        scale = 1000 if units == "mm" else 1
+        assert (
+            fig._surf_maps[0]["surf"]["rr"][0, 0] == scale * maps[0]["surf"]["rr"][0, 0]
+        )
+        renderer.backend._close_all()
 
     # Test some methods
     fig = evoked.plot_field(maps, time_viewer=True)
@@ -214,6 +225,7 @@ def test_plot_evoked_field(renderer):
 
     fig = evoked.plot_field(maps, time_viewer=False)
     assert isinstance(fig, Figure3D)
+    renderer.backend._close_all()
 
 
 @testing.requires_testing_data