Only add faces to shells that have a surface area larger than some threshold value

src/ifcgeom/IfcGeom.h

@@ -47,8 +47,10 @@
 #define DEFLECTION_TOLERANCE 0.001
 // Specifies the tolerance of the wire builder, most notably for trimmed curves
 #define WIRE_CREATION_TOLERANCE 0.0001
+// Specifies the minimal area of a face to be included in an IfcConnectedFaceset
+#define MINIMAL_FACE_AREA 0.000001
 // Specifies the treshold distance under which cartesian points are deemed equal
-#define POINT_EQUALITY_TOLERANCE 0.0000001
+#define POINT_EQUALITY_TOLERANCE 0.00001
 
 // Specifies maximum number of faces for a shell to be sewed. Sewing shells
 // that consist of many faces is really detrimental for the performance.
@@ -72,6 +74,7 @@ namespace IfcGeom {
 	const TopoDS_Shape& ensure_fit_for_subtraction(const TopoDS_Shape& shape, TopoDS_Shape& solid);
 	bool profile_helper(int numVerts, double* verts, int numFillets, int* filletIndices, double* filletRadii, gp_Trsf2d trsf, TopoDS_Face& face); 
 	double shape_volume(const TopoDS_Shape& s);
+	double face_area(const TopoDS_Face& f);
 	namespace Cache {
 		void Purge();
 		void PurgeShapeCache();

src/ifcgeom/IfcGeomFaces.cpp

@@ -73,8 +73,6 @@
 #include <ShapeFix_ShapeTolerance.hxx>
 #include <ShapeFix_Solid.hxx>
 
-#include <BRepFilletAPI_MakeFillet2d.hxx>
-
 #include <TopLoc_Location.hxx>
 
 #include "../ifcgeom/IfcGeom.h"
@@ -97,28 +95,33 @@ bool IfcGeom::convert(const Ifc2x3::IfcFace::ptr l, TopoDS_Face& face) {
 	if ( er != BRepBuilderAPI_FaceDone ) return false;
 	if ( bounds->Size() == 1 ) {
 		face = mf.Face();
-		return true;
-	}
-	for( ++it; it != bounds->end(); ++ it) {
-		Ifc2x3::IfcLoop::ptr loop = (*it)->Bound();
-		TopoDS_Wire wire;
-		if ( ! IfcGeom::convert_wire(loop,wire) ) return false;
-		mf.Add(wire);
-	}
-	if ( mf.IsDone() ) {
-		ShapeFix_Shape sfs(mf.Face());
-		sfs.Perform();
-		TopoDS_Shape sfs_shape = sfs.Shape();
-		bool is_face = sfs_shape.ShapeType() == TopAbs_FACE;
-		if ( is_face ) {
-			face = TopoDS::Face(sfs_shape);
-			return true;
+	} else {
+		for( ++it; it != bounds->end(); ++ it) {
+			Ifc2x3::IfcLoop::ptr loop = (*it)->Bound();
+			TopoDS_Wire wire;
+			if ( ! IfcGeom::convert_wire(loop,wire) ) return false;
+			mf.Add(wire);
+		}
+		if ( mf.IsDone() ) {
+			ShapeFix_Shape sfs(mf.Face());
+			sfs.Perform();
+			TopoDS_Shape sfs_shape = sfs.Shape();
+			bool is_face = sfs_shape.ShapeType() == TopAbs_FACE;
+			if ( is_face ) {
+				face = TopoDS::Face(sfs_shape);
+			} else {
+				return false;
+			}
 		} else {
 			return false;
 		}
-	} else {
-		return false;
 	}
+	// It might be a good idea to globally discard faces
+	// smaller than a certain treshold value. But for now
+	// only when processing IfcConnectedFacesets the small
+	// faces are skipped.
+	// return face_area(face) > 0.0001;
+	return true;
 }
 bool IfcGeom::convert(const Ifc2x3::IfcArbitraryClosedProfileDef::ptr l, TopoDS_Face& face) {
 	TopoDS_Wire wire;

src/ifcgeom/IfcGeomFunctions.cpp

@@ -88,7 +88,9 @@
 
 bool IfcGeom::create_solid_from_compound(const TopoDS_Shape& compound, TopoDS_Shape& shape) {
 	BRepOffsetAPI_Sewing builder;
-	builder.SetTolerance(0.01);
+	builder.SetTolerance(POINT_EQUALITY_TOLERANCE);
+	builder.SetMaxTolerance(POINT_EQUALITY_TOLERANCE);
+	builder.SetMinTolerance(POINT_EQUALITY_TOLERANCE);
 	TopExp_Explorer exp(compound,TopAbs_FACE);
 	if ( ! exp.More() ) return false;
 	for ( ; exp.More(); exp.Next() ) {
@@ -99,7 +101,7 @@ bool IfcGeom::create_solid_from_compound(const TopoDS_Shape& compound, TopoDS_Sh
 	shape = builder.SewedShape();
 	try {
 	ShapeFix_Solid sf_solid;
-	sf_solid.LimitTolerance(0.01);
+	sf_solid.LimitTolerance(POINT_EQUALITY_TOLERANCE);
 	shape = sf_solid.SolidFromShell(TopoDS::Shell(shape));
 	} catch(...) {}
 	return true;
@@ -259,9 +261,14 @@ bool IfcGeom::profile_helper(int numVerts, double* verts, int numFillets, int* f
 	return true;
 }
 double IfcGeom::shape_volume(const TopoDS_Shape& s) {
-	GProp_GProps System;
-	BRepGProp::VolumeProperties(s, System);
-	return (double) System.Mass();
+	GProp_GProps prop;
+	BRepGProp::VolumeProperties(s, prop);
+	return prop.Mass();
+}
+double IfcGeom::face_area(const TopoDS_Face& f) {
+	GProp_GProps prop;
+	BRepGProp::SurfaceProperties(f,prop);
+	return prop.Mass();
 }
 bool IfcGeom::is_convex(const TopoDS_Wire& wire) {
 	for ( TopExp_Explorer exp1(wire,TopAbs_VERTEX); exp1.More(); exp1.Next() ) {

src/ifcgeom/IfcGeomShapes.cpp

@@ -296,10 +296,12 @@ bool IfcGeom::convert(const Ifc2x3::IfcConnectedFaceSet::ptr l, TopoDS_Shape& sh
 	const unsigned int num_faces = faces->Size();
 	if ( Ifc::SewShells && num_faces < MAX_FACES_TO_SEW ) {
 		BRepOffsetAPI_Sewing builder;
-		builder.SetTolerance(0.01);
+		builder.SetTolerance(POINT_EQUALITY_TOLERANCE);
+		builder.SetMaxTolerance(POINT_EQUALITY_TOLERANCE);
+		builder.SetMinTolerance(POINT_EQUALITY_TOLERANCE);
 		for( Ifc2x3::IfcFace::it it = faces->begin(); it != faces->end(); ++ it ) {
 			TopoDS_Face face;
-			if ( IfcGeom::convert_face(*it,face) ) {
+			if ( IfcGeom::convert_face(*it,face) && face_area(face) > MINIMAL_FACE_AREA ) {
 				builder.Add(face);
 				facesAdded = true;
 			} else {
@@ -311,7 +313,7 @@ bool IfcGeom::convert(const Ifc2x3::IfcConnectedFaceSet::ptr l, TopoDS_Shape& sh
 		shape = builder.SewedShape();
 		try {
 			ShapeFix_Solid solid;
-			solid.LimitTolerance(0.01);
+			solid.LimitTolerance(POINT_EQUALITY_TOLERANCE);
 			shape = solid.SolidFromShell(TopoDS::Shell(shape));
 		} catch(...) {}
 	} else {
@@ -320,7 +322,7 @@ bool IfcGeom::convert(const Ifc2x3::IfcConnectedFaceSet::ptr l, TopoDS_Shape& sh
 		builder.MakeCompound(compound);
 		for( Ifc2x3::IfcFace::it it = faces->begin(); it != faces->end(); ++ it ) {
 			TopoDS_Face face;
-			if ( IfcGeom::convert_face(*it,face) ) {
+			if ( IfcGeom::convert_face(*it,face) && face_area(face) > MINIMAL_FACE_AREA ) {
 				builder.Add(compound,face);
 				facesAdded = true;
 			} else {