FIX: Handle surfaces with only undefined values (#656)

schema/definitions/0.8.0/schema/fmu_meta.json

@@ -291,12 +291,12 @@
           "type": "number"
         },
         "zmax": {
-          "description": "Maximum z-coordinate",
+          "description": "Maximum z-coordinate. For regular surfaces this field represents the maximum surface value and it will be absent if all values are undefined.",
           "title": "Zmax",
           "type": "number"
         },
         "zmin": {
-          "description": "Minimum z-coordinate",
+          "description": "Minimum z-coordinate. For regular surfaces this field represents the minimum surface value and it will be absent if all values are undefined.",
           "title": "Zmin",
           "type": "number"
         }

src/fmu/dataio/datastructure/meta/content.py

@@ -142,11 +142,17 @@ class BoundingBox2D(BaseModel):
 
 class BoundingBox3D(BoundingBox2D):
     zmin: float = Field(
-        description="Minimum z-coordinate",
+        description=(
+            "Minimum z-coordinate. For regular surfaces this field represents the "
+            "minimum surface value and it will be absent if all values are undefined."
+        ),
         allow_inf_nan=False,
     )
     zmax: float = Field(
-        description="Maximum z-coordinate",
+        description=(
+            "Maximum z-coordinate. For regular surfaces this field represents the "
+            "maximum surface value and it will be absent if all values are undefined."
+        ),
         allow_inf_nan=False,
     )
 

src/fmu/dataio/providers/objectdata/_xtgeo.py

@@ -48,20 +48,29 @@ def get_spec(self) -> dict[str, Any]:
         )
 
     def get_bbox(self) -> dict[str, Any]:
-        """Derive data.bbox for xtgeo.RegularSurface."""
+        """
+        Derive data.bbox for xtgeo.RegularSurface. The zmin/zmax fields represents
+        the minimum/maximum surface values and should be absent in the metadata if the
+        surface only has undefined values.
+        """
         logger.info("Get bbox for RegularSurface")
 
-        return meta.content.BoundingBox3D(
+        if np.isfinite(self.obj.values).any():
+            return meta.content.BoundingBox3D(
+                xmin=float(self.obj.xmin),
+                xmax=float(self.obj.xmax),
+                ymin=float(self.obj.ymin),
+                ymax=float(self.obj.ymax),
+                zmin=float(self.obj.values.min()),
+                zmax=float(self.obj.values.max()),
+            ).model_dump(mode="json", exclude_none=True)
+
+        return meta.content.BoundingBox2D(
             xmin=float(self.obj.xmin),
             xmax=float(self.obj.xmax),
             ymin=float(self.obj.ymin),
             ymax=float(self.obj.ymax),
-            zmin=float(self.obj.values.min()),
-            zmax=float(self.obj.values.max()),
-        ).model_dump(
-            mode="json",
-            exclude_none=True,
-        )
+        ).model_dump(mode="json", exclude_none=True)
 
     def get_objectdata(self) -> DerivedObjectDescriptor:
         """Derive object data for xtgeo.RegularSurface."""

tests/conftest.py

@@ -8,6 +8,7 @@
 from pathlib import Path
 
 import fmu.dataio as dio
+import numpy as np
 import pandas as pd
 import pytest
 import xtgeo
@@ -401,6 +402,22 @@ def metadata_examples():
     return _metadata_examples()
 
 
+@pytest.fixture(name="regsurf_nan_only", scope="module")
+def fixture_regsurf_nan_only():
+    """Create an xtgeo surface with only NaNs."""
+    logger.debug("Ran %s", _current_function_name())
+    return xtgeo.RegularSurface(ncol=12, nrow=10, xinc=20, yinc=20, values=np.nan)
+
+
+@pytest.fixture(name="regsurf_masked_only", scope="module")
+def fixture_regsurf_masked_only():
+    """Create an xtgeo surface with only masked values."""
+    logger.debug("Ran %s", _current_function_name())
+    regsurf = xtgeo.RegularSurface(ncol=12, nrow=10, xinc=20, yinc=20, values=1000)
+    regsurf.values = np.ma.masked_array(regsurf.values, mask=True)
+    return regsurf
+
+
 # ======================================================================================
 # Various objects
 # ======================================================================================

tests/test_schema/test_pydantic_logic.py

@@ -4,7 +4,7 @@
 from copy import deepcopy
 
 import pytest
-from fmu.dataio.datastructure.meta import Root
+from fmu.dataio.datastructure.meta import Root, content
 from pydantic import ValidationError
 
 from ..utils import _metadata_examples
@@ -377,3 +377,29 @@ def test_content_whitelist(metadata_examples):
     example_surface["data"]["content"] = "not_valid_content"
     with pytest.raises(ValidationError):
         Root.model_validate(example_surface)
+
+
+def test_zmin_zmax_not_present_for_surfaces(metadata_examples):
+    """
+    Test that the validation works for surface metadata without
+    zmin/zmax info or with zmin/zmax = None.
+    """
+
+    # fetch surface example
+    example_surface = deepcopy(metadata_examples["surface_depth.yml"])
+
+    # assert validation with no changes and check that bbox is 3D
+    model = Root.model_validate(example_surface)
+    assert isinstance(model.root.data.root.bbox, content.BoundingBox3D)
+
+    # assert validation works with zmin/zmax = None, bbox should be 2D
+    example_surface["data"]["bbox"]["zmin"] = None
+    example_surface["data"]["bbox"]["zmax"] = None
+    model = Root.model_validate(example_surface)
+    assert isinstance(model.root.data.root.bbox, content.BoundingBox2D)
+
+    # assert validation works without zmin/zmax, bbox should be 2D
+    del example_surface["data"]["bbox"]["zmin"]
+    del example_surface["data"]["bbox"]["zmax"]
+    model = Root.model_validate(example_surface)
+    assert isinstance(model.root.data.root.bbox, content.BoundingBox2D)

tests/test_units/test_dataio.py

@@ -429,6 +429,32 @@ def test_content_deprecated_seismic_offset(regsurf, globalconfig2):
     }
 
 
+def test_surfaces_with_non_finite_values(
+    globalconfig1, regsurf_masked_only, regsurf_nan_only, regsurf
+):
+    """
+    When a surface has no finite values the zmin/zmax should not be present
+    in the metadata.
+    """
+
+    eobj = ExportData(config=globalconfig1, content="time")
+
+    # test surface with only masked values
+    mymeta = eobj.generate_metadata(regsurf_masked_only)
+    assert "zmin" not in mymeta["data"]["bbox"]
+    assert "zmax" not in mymeta["data"]["bbox"]
+
+    # test surface with only nan values
+    mymeta = eobj.generate_metadata(regsurf_nan_only)
+    assert "zmin" not in mymeta["data"]["bbox"]
+    assert "zmax" not in mymeta["data"]["bbox"]
+
+    # test surface with finite values has zmin/zmax
+    mymeta = eobj.generate_metadata(regsurf)
+    assert "zmin" in mymeta["data"]["bbox"]
+    assert "zmax" in mymeta["data"]["bbox"]
+
+
 def test_workflow_as_string(fmurun_w_casemetadata, monkeypatch, globalconfig1, regsurf):
     """
     Check that having workflow as string works both in ExportData and on export.