Add a unit-test for LevelSetFilter::fillet.

Signed-off-by: apradhana <[email protected]>

openvdb/openvdb/tools/LevelSetFilter.h

@@ -98,11 +98,15 @@ class LevelSetFilter : public LevelSetTracker<GridT, InterruptT>
     /// @brief One iteration of filleting on the level set.
     /// @param mask Optional alpha mask.
     ///
-    /// @note This filter rounds off concave edges to create a smoother transition between surfaces
-    /// Fillets a level set by
-    ///   offsetting at locations with a negative principal curvature, proportional to its magnitude
-    ///   leaves locations with non-negative principal curvatures untouched
-    /// This filter converges to the convex hull if iterated enough times
+    /// @note This filter rounds off concave edges to create a smoother
+    /// transition between surfaces. Fillets a level set by offsetting
+    /// at locations with a negative principal curvature, proportional
+    /// to its magnitude leaves locations with non-negative principal
+    /// curvatures untouched. This filter converges to the convex hull
+    /// if iterated enough times.
+    ///
+    /// @details See also Level Set Methods and Fast Marching Methods
+    /// by James Sethian, pp. 204.
     void fillet(const MaskType* mask = nullptr)
     {
         Filter f(this, mask); f.fillet();
@@ -409,10 +413,10 @@ LevelSetFilter<GridT, MaskT, InterruptT>::Filter::meanCurvatureImpl(const LeafRa
     }
 }
 
-/// Fillets a level set by
-///   offsetting at locations with a negative principal curvature, proportional to its magnitude
-///   leaves locations with non-negative principal curvatures untouched
-/// This filter converges to the convex hull if iterated enough times
+/// Fillets a level set by offsetting at locations with a negative principal
+/// curvature, proportional to its magnitude. Leaves locations with non-negative
+/// principal curvatures untouched. This filter converges to the convex hull if
+/// iterated enough times.
 template<typename GridT, typename MaskT, typename InterruptT>
 inline void
 LevelSetFilter<GridT, MaskT, InterruptT>::Filter::filletImpl(const LeafRange& range)

openvdb/openvdb/unittest/CMakeLists.txt

@@ -118,6 +118,7 @@ else()
     TestLeafManager.cc
     TestLeafMask.cc
     TestLeafOrigin.cc
+    TestLevelSetFilter.cc
     TestLevelSetRayIntersector.cc
     TestLevelSetUtil.cc
     TestLinearInterp.cc

openvdb/openvdb/unittest/TestLevelSetFilter.cc

@@ -0,0 +1,80 @@
+// Copyright Contributors to the OpenVDB Project
+// SPDX-License-Identifier: Apache-2.0
+
+#include <openvdb/openvdb.h>
+#include <openvdb/tools/LevelSetFilter.h>
+#include <openvdb/tools/LevelSetSphere.h>
+#include <openvdb/io/File.h>
+#include <openvdb/tools/Composite.h>        // for csgUnion()
+
+#include <gtest/gtest.h>
+
+using namespace openvdb;
+
+class TestLevelSetFilter: public ::testing::Test
+{
+public:
+    void SetUp() override { openvdb::initialize(); }
+    void TearDown() override { openvdb::uninitialize(); }
+
+    void testLevelSetFillet();
+}; // class TestLevelSetFilter
+
+
+////////////////////////////////////////
+
+
+TEST_F(TestLevelSetFilter, testLevelSetFillet)
+{
+    using GridT = FloatGrid;
+    using FilterT = tools::LevelSetFilter<GridT>;
+
+    const float radius = 5.0f;
+    const float voxelSize = 1.0f;
+    const float halfWidth = 3.0f;
+    typename GridT::Ptr sdfGrid = tools::createLevelSetSphere<GridT>(/*radius=*/radius,
+            /*center=*/Vec3f(-radius, 0.0f, 0.0f),
+            /*dx=*/voxelSize, /*halfWidth*/ halfWidth);
+    typename GridT::Ptr sdfGridB = tools::createLevelSetSphere<GridT>(/*radius=*/radius,
+            /*center=*/Vec3f(radius, 0.0f, 0.0f),
+            /*dx=*/voxelSize, /*halfWidth*/ halfWidth);
+    typename GridT::Accessor acc = sdfGrid->getAccessor();
+
+    EXPECT_TRUE(sdfGrid);
+    EXPECT_TRUE(sdfGridB);
+
+    tools::csgUnion(*sdfGrid, *sdfGridB);
+
+    {
+        EXPECT_TRUE(sdfGrid);
+
+        Coord ijk(0, 3, 0);
+
+        // We expect that the intersection between the two spheres are at (0, 0, 0)
+        // so the SDF value of the union in these offsets locations should be > 0
+        EXPECT_TRUE(acc.getValue(ijk) > 0.f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0, 0, 1)) > 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0, 0,-1)) > 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1, 0)) > 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1, 1)) > 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1,-1)) > 0.0f);
+    }
+
+    FilterT filter(*sdfGrid);
+    filter.fillet();
+
+    {
+        EXPECT_TRUE(sdfGrid);
+
+        Coord ijk(0, 3, 0);
+
+        // After the fillet operation, we expect that the zero-isocontour is
+        // pushed outward.
+        EXPECT_TRUE(acc.getValue(ijk) < 0.f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0, 0, 1)) < 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0, 0,-1)) < 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1, 0)) < 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1, 1)) < 0.0f);
+        EXPECT_TRUE(acc.getValue(ijk.offsetBy(0,-1,-1)) < 0.0f);
+    }
+}

pendingchanges/levelset_fillet.txt

@@ -0,0 +1,2 @@
+New Feature:
+- Added fillet() method in tools::LevelSetFilter to round off concave edges to create smoother transition between surfaces. [Contributed by Greg Hurst]