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Fixed an issue with smooth position rasterization which wouldn't alwa…
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…ys activate the correct topology if the search radius was larger than the point radius

Signed-off-by: Nick Avramoussis <[email protected]>
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@Idclip
Idclip committed Oct 24, 2023
1 parent 36bee2d commit de71777
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Showing 4 changed files with 206 additions and 32 deletions.
4 changes: 4 additions & 0 deletions openvdb/openvdb/points/PointRasterizeSDF.h
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Original file line number Diff line number Diff line change
Expand Up @@ -257,6 +257,10 @@ struct SmoothSphereSettings
/// larger than the point radius. Both this and the `radiusScale`
/// parameters are given in world space units and are applied to every
/// point to generate a surface mask.
/// @warning If this value is less than the sum of the maximum particle
/// radius and the half band width, the exterior half band width may be
/// smaller than desired. In these cases, consider running a levelset
/// renormalize or a levelset rebuild.
Real searchRadius = 1.0;
};

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188 changes: 157 additions & 31 deletions openvdb/openvdb/points/impl/PointRasterizeSDFImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -643,18 +643,23 @@ struct SurfaceMaskOp
protected:
SurfaceMaskOp(const math::Transform& points,
const math::Transform& surface,
// Clip the surface to this bounds. Only used for the smooth
// raster workflow to limit to search radii topology init
const CoordBBox* const maxClipBounds = nullptr,
InterrupterT* interrupter = nullptr)
: mMask(new MaskTreeT)
, mMaskOff(new MaskTreeT)
, mPointsTransform(points)
, mSurfaceTransform(surface)
, mMaxClipBounds(maxClipBounds ? this->toSurfaceBounds(*maxClipBounds) : CoordBBox::inf())
, mInterrupter(interrupter) {}

SurfaceMaskOp(const SurfaceMaskOp& other)
: mMask(new MaskTreeT)
, mMaskOff(new MaskTreeT)
, mPointsTransform(other.mPointsTransform)
, mSurfaceTransform(other.mSurfaceTransform)
, mMaxClipBounds(other.mMaxClipBounds)
, mInterrupter(other.mInterrupter) {}

// @brief Sparse fill a tree with activated bounding boxes expanded from
Expand Down Expand Up @@ -696,8 +701,16 @@ struct SurfaceMaskOp
this->deactivate(bounds);
}

inline void activate(const CoordBBox& bounds) { mMask->sparseFill(bounds, true, true); }
inline void deactivate(const CoordBBox& bounds) { mMaskOff->sparseFill(bounds, true, true); }
inline void activate(CoordBBox& bounds)
{
bounds.intersect(mMaxClipBounds);
mMask->sparseFill(bounds, true, true);
}

inline void deactivate(const CoordBBox& bounds)
{
mMaskOff->sparseFill(bounds, true, true);
}

inline bool interrupted()
{
Expand Down Expand Up @@ -752,6 +765,7 @@ struct SurfaceMaskOp
std::unique_ptr<MaskTreeT> mMaskOff;
const math::Transform& mPointsTransform;
const math::Transform& mSurfaceTransform;
const CoordBBox mMaxClipBounds;
InterrupterT* mInterrupter;
};

Expand All @@ -769,8 +783,9 @@ struct FixedSurfaceMaskOp
const math::Transform& surface,
const double minBandRadius, // sdf index space
const double maxBandRadius, // sdf index space
const CoordBBox* const maxClipBounds,
InterrupterT* interrupter = nullptr)
: BaseT(points, surface, interrupter)
: BaseT(points, surface, maxClipBounds, interrupter)
, mMin(), mMax()
{
// calculate the min interior cube area of activity. this is the side
Expand Down Expand Up @@ -827,13 +842,15 @@ struct VariableSurfaceMaskOp

VariableSurfaceMaskOp(const math::Transform& pointsTransform,
const math::Transform& surfaceTransform,
const RadiusTreeT& min,
const RadiusTreeT* const min,
const RadiusTreeT& max,
const Real scale,
const Real minScale,
const Real maxScale,
const Real halfband,
const CoordBBox* const maxClipBounds,
InterrupterT* interrupter = nullptr)
: BaseT(pointsTransform, surfaceTransform, interrupter)
, mMin(min), mMax(max), mScale(scale)
: BaseT(pointsTransform, surfaceTransform, maxClipBounds, interrupter)
, mMin(min), mMax(max), mMinScale(minScale), mMaxScale(maxScale)
, mHalfband(halfband) {}

VariableSurfaceMaskOp(const VariableSurfaceMaskOp&) = default;
Expand All @@ -848,7 +865,9 @@ struct VariableSurfaceMaskOp
const int32_t max = this->maxDist(maxacc.getValue(leafIter->origin()));
this->activate(*leafIter, max);
}
const tree::ValueAccessor<const RadiusTreeT> minacc(mMin);

if (!mMin) return;
const tree::ValueAccessor<const RadiusTreeT> minacc(*mMin);
for (auto leafIter = range.begin(); leafIter; ++leafIter) {
const int32_t min = this->minDist(minacc.getValue(leafIter->origin()));
if (min < 0) continue;
Expand All @@ -860,14 +879,14 @@ struct VariableSurfaceMaskOp
inline int32_t maxDist(const typename RadiusTreeT::ValueType& maxRadiusWs) const
{
// max radius in index space
const Real maxBandRadius = (Real(maxRadiusWs) * mScale) + mHalfband;
const Real maxBandRadius = (Real(maxRadiusWs) * mMaxScale) + mHalfband;
return static_cast<int32_t>(math::Round(maxBandRadius)); // furthest voxel
}

inline int32_t minDist(const typename RadiusTreeT::ValueType& minRadiusWs) const
{
// min radius in index space
Real minBandRadius = math::Max(0.0, (Real(minRadiusWs) * mScale) - mHalfband);
Real minBandRadius = math::Max(0.0, (Real(minRadiusWs) * mMinScale) - mHalfband);
// calculate the min interior cube area of activity. this is the side
// of the largest possible cube that fits into the radius "min":
// d = 2r -> 2r = 3x^2 -> x = 2r / sqrt(3)
Expand All @@ -889,9 +908,9 @@ struct VariableSurfaceMaskOp
}

private:
const RadiusTreeT& mMin;
const RadiusTreeT* const mMin;
const RadiusTreeT& mMax;
const Real mScale, mHalfband;
const Real mMinScale, mMaxScale, mHalfband;
};

template <typename SdfT, typename MaskTreeT>
Expand Down Expand Up @@ -945,7 +964,7 @@ initFixedSdf(const PointDataGridT& points,
if (interrupter) interrupter->start("Generating uniform surface topology");

FixedSurfaceMaskOp<MaskTreeT, InterrupterT> op(points.transform(),
*transform, minBandRadius, maxBandRadius, interrupter);
*transform, minBandRadius, maxBandRadius, /*clipbounds=*/nullptr, interrupter);

LeafManagerT manager(points.tree());
tbb::parallel_reduce(manager.leafRange(), op);
Expand Down Expand Up @@ -977,7 +996,72 @@ initVariableSdf(const PointDataGridT& points,
if (interrupter) interrupter->start("Generating variable surface topology");

VariableSurfaceMaskOp<RadiusTreeT, MaskTreeT, InterrupterT>
op(points.transform(), *transform, min, max, scale, halfband, interrupter);
op(points.transform(), *transform, &min, max, scale, scale, halfband,
/*clipbounds=*/nullptr, interrupter);

LeafManagerT manager(points.tree());
tbb::parallel_reduce(manager.leafRange(), op);

typename SdfT::Ptr surface =
initSdfFromMasks<SdfT, MaskTreeT>(transform, bg, op.mask(), op.maskoff());

if (interrupter) interrupter->end();
return surface;
}

template <typename SdfT, typename InterrupterT, typename PointDataGridT>
inline typename SdfT::Ptr
initFixedSmoothSdf(const PointDataGridT& points,
math::Transform::Ptr transform,
const typename SdfT::ValueType bg,
const Real maxBandRadius,
const CoordBBox& bounds,
InterrupterT* interrupter)
{
using LeafManagerT = tree::LeafManager<const typename PointDataGridT::TreeType>;
using MaskTreeT = typename SdfT::TreeType::template ValueConverter<ValueMask>::Type;

if (interrupter) interrupter->start("Generating uniform surface topology");

// @note Currently don't use min radii to deactivate, can't compute
// this with the ZB kernel
FixedSurfaceMaskOp<MaskTreeT, InterrupterT> op(points.transform(),
*transform, /*minBandRadius=*/0.0, maxBandRadius, &bounds, interrupter);

LeafManagerT manager(points.tree());
tbb::parallel_reduce(manager.leafRange(), op);

typename SdfT::Ptr surface =
initSdfFromMasks<SdfT, MaskTreeT>(transform, bg, op.mask(), op.maskoff());

if (interrupter) interrupter->end();
return surface;
}

template <typename SdfT,
typename InterrupterT,
typename PointDataGridT,
typename RadiusTreeT>
inline typename SdfT::Ptr
initVariableSmoothSdf(const PointDataGridT& points,
math::Transform::Ptr transform,
const typename SdfT::ValueType bg,
const RadiusTreeT& maxTree,
const Real scale,
const Real halfband,
const CoordBBox& bounds,
InterrupterT* interrupter)
{
using LeafManagerT = tree::LeafManager<const typename PointDataGridT::TreeType>;
using MaskTreeT = typename SdfT::TreeType::template ValueConverter<ValueMask>::Type;

if (interrupter) interrupter->start("Generating variable surface topology");

// @note Currently don't use min radii/tree to deactivate, can't
// compute this with the ZB kernel
VariableSurfaceMaskOp<RadiusTreeT, MaskTreeT, InterrupterT>
op(points.transform(), *transform, nullptr, maxTree, /*minscale=*/1.0,
scale, halfband, &bounds, interrupter);

LeafManagerT manager(points.tree());
tbb::parallel_reduce(manager.leafRange(), op);
Expand Down Expand Up @@ -1272,54 +1356,96 @@ rasterizeSmoothSpheres(const PointDataGridT& points,
static_cast<typename SdfT::ValueType>(vs * halfband);

const Real indexSpaceSearch = settings.searchRadius / vs;
// max possible index space search radius
const size_t width = static_cast<size_t>(math::RoundUp(indexSpaceSearch));

// The topology we need to activate is at a distance based on the maximum
// radii of each point and the uniform search radius. Even though we're
// guaranteed to be generating new positions within the distribution of
// point neighbours, these positions may end up outside of active topology
// were we _only_ to use the radius of the particles for topology
// activation.
const Real maxActivationRadius = std::max(settings.searchRadius, settings.radiusScale) / vs;
const auto leaf = points.constTree().cbeginLeaf();

// Compute estimated max bounds for clipping. This is used if the search
// radius is larger than the max particle radius (as we don't need to
// activate topology further outside the bounds of the point data grid).
// This bounds is expanded by the halfband + max radii
CoordBBox bounds;
points.tree().evalLeafBoundingBox(bounds);

typename SdfT::Ptr surface;
GridPtrVec grids;

if (settings.radius.empty())
{
const FixedBandRadius<Real> bands(settings.radiusScale / vs, halfband);
// This is the max possible distance we need to activate, but we'll
// clip this at the edges of the point bounds (as the ZB kernel will
// only create positions in between points).
const FixedBandRadius<Real> bands(maxActivationRadius, halfband);
const Real max = bands.max();

surface = initFixedSdf<SdfT, InterrupterType>
(points, transform, background, /*min*/0.0, max, interrupter);
// Compute max radius in index space and expand bounds
bounds.expand(static_cast<Coord::ValueType>(halfband + math::Round(settings.radiusScale / vs)));
// init surface
surface = initFixedSmoothSdf<SdfT, InterrupterType>
(points, transform, background, max, bounds, interrupter);

if (!leaf) return GridPtrVec(1, surface);

// max possible index space search radius
const size_t width = static_cast<size_t>(math::RoundUp(indexSpaceSearch));

const FixedRadius<Real> rad(settings.radiusScale / vs);
if (interrupter) interrupter->start("Rasterizing particles to level set using constant Zhu-Bridson");

grids = doRasterizeSurface<SdfT, AveragePositionTransfer, AttributeTypes, InterrupterType>
(points, attributes, filter, *surface, interrupter,
width, rad, indexSpaceSearch, points.transform(), *surface); // args
}
else {
else
{
using RadiusT = typename SettingsT::RadiusAttributeType;
using PointDataTreeT = typename PointDataGridT::TreeType;
using RadTreeT = typename PointDataTreeT::template ValueConverter<RadiusT>::Type;

// We currently don't use the min values for the ZB kernel topology
// activation.
// @todo We should be able to deactivate on some metric
RadiusT min(0), max(0);
typename RadTreeT::Ptr mintree(new RadTreeT), maxtree(new RadTreeT);
typename RadTreeT::Ptr maxtree(new RadTreeT);
points::evalMinMax<RadiusT, UnknownCodec>
(points.tree(), settings.radius, min, max, filter, mintree.get(), maxtree.get());
(points.tree(), settings.radius, min, max, filter, nullptr, maxtree.get());

if ((settings.searchRadius > settings.radiusScale) && (min < settings.searchRadius)) {
// set radius tree values to search distances if they are less,
// just for the surface topology initialization. This is the max
// possible distance we need to activate, but we'll clip this at
// the edges of the point bounds (as the ZB kernel will only
// create positions in-between points).
tools::foreach(maxtree->beginValueOn(),
[&](auto& iter) {
iter.modifyValue([&](auto& r) {
if (r < settings.searchRadius) {
// initVariableSmoothSdf scales radii by (settings.radiusScale/vs).
// We don't want to scale the search radii by the radius scale, so
// cancel it out here.
r = static_cast<RadiusT>(settings.searchRadius / settings.radiusScale);
}
});
}, /*thread=*/true, /*shared=*/true);
}

// search distance at the SDF transform
const RadiusT indexSpaceScale = RadiusT(settings.radiusScale / vs);
surface = initVariableSdf<SdfT, InterrupterType>
(points, transform, background, *mintree, *maxtree,
indexSpaceScale, halfband, interrupter);
mintree.reset();
// Compute max radius in index space and expand bounds
bounds.expand(static_cast<Coord::ValueType>(halfband + math::Round(max * indexSpaceScale)));

// init surface
surface = initVariableSmoothSdf<SdfT, InterrupterType>
(points, transform, background, *maxtree,
indexSpaceScale, halfband, bounds, interrupter);
maxtree.reset();

if (!leaf) return GridPtrVec(1, surface);

// max possible index space search radius
const size_t width = static_cast<size_t>(math::RoundUp(indexSpaceSearch));

const size_t ridx = leaf->attributeSet().find(settings.radius);
if (ridx == AttributeSet::INVALID_POS) {
OPENVDB_THROW(RuntimeError, "Failed to find radius attribute");
Expand Down
44 changes: 43 additions & 1 deletion openvdb/openvdb/unittest/TestPointRasterizeSDF.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -704,6 +704,48 @@ TEST_F(TestPointRasterizeSDF, testRasterizeSmoothSpheres)
}
}

// Test two points qhich create a ghost particle outside of their
// radii (to test that the surface topology correctly accounts for the
// search distance)
{
FixedSurfacing<points::NullFilter> s;
s.halfband = 2;
s.points = PointBuilder({ Vec3f(0), Vec3f(0,5,0) }).voxelsize(0.1).get();
s.transform = nullptr;
double radius = 0.5, search = 5; // large search

FloatGrid::Ptr sdf = s.surfaceSmooth(radius, search);
EXPECT_TRUE(sdf && sdf->getName() == "fixed_avg");
EXPECT_TRUE(sdf->transform() == s.points->transform());
EXPECT_EQ(GRID_LEVEL_SET, sdf->getGridClass());
EXPECT_EQ(float(s.halfband * s.points->voxelSize()[0]), sdf->background());

// @todo regression test. find a way to better test these values
size_t interiorOn = 0, exteriorOn = 0;
EXPECT_EQ(Index32(36), sdf->tree().leafCount());
EXPECT_EQ(Index64(0), sdf->tree().activeTileCount());
EXPECT_EQ(Index64(4188), sdf->tree().activeVoxelCount());

for (auto iter = sdf->cbeginValueOn(); iter; ++iter) {
EXPECT_TRUE(*iter > -sdf->background());
EXPECT_TRUE(*iter < sdf->background());
if (*iter > 0) ++exteriorOn;
else ++interiorOn;
}
EXPECT_EQ(size_t(1244), interiorOn);
EXPECT_EQ(size_t(2944), exteriorOn);

size_t interiorOff = 0, exteriorOff = 0;
for (auto iter = sdf->cbeginValueOff(); iter; ++iter) {
EXPECT_TRUE((*iter <= -sdf->background()) || (*iter >= sdf->background()))
<< *iter << " " << sdf->background();;
if (*iter > 0) ++exteriorOff;
else ++interiorOff;
}
EXPECT_EQ(size_t(323), interiorOff);
EXPECT_EQ(size_t(308789), exteriorOff);
}

// Test multiple points - 8 points at cube corner positions
{
FixedSurfacing<points::NullFilter> s;
Expand All @@ -726,7 +768,7 @@ TEST_F(TestPointRasterizeSDF, testRasterizeSmoothSpheres)

// test points from a box with coords at 0.5 and a search radius
// large enough to create a smoothed box
// @todo find a way to better test these values
// @todo regression test. find a way to better test these values
positions = getBoxPoints(/*scale*/0.5f);
radius = 0.2, search = 1.2;
s.halfband = 3;
Expand Down
2 changes: 2 additions & 0 deletions pendingchanges/surfacing.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -22,4 +22,6 @@ OpenVDB:
- Fixed a bug in points::rasterizeSpheres and points::rasterizeSmoothSpheres
which could cause sections of the generated surface to incorrectly be marked
as negative interior values.
- Fixed a bug in points::rasterizeSmoothSpheres which could result in
incomplete surface reconstruction with significantly larger search distances.
- Fixed some precision issues in various Matrix methods

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