diff --git a/lib/Slic3r/Fill.pm b/lib/Slic3r/Fill.pm
index 8e2f51e0a..95bd8e5af 100644
--- a/lib/Slic3r/Fill.pm
+++ b/lib/Slic3r/Fill.pm
@@ -13,7 +13,7 @@ use Slic3r::Fill::PlanePath;
 use Slic3r::Fill::Rectilinear;
 use Slic3r::ExtrusionPath ':roles';
 use Slic3r::Geometry qw(X Y PI scale chained_path);
-use Slic3r::Geometry::Clipper qw(union_ex diff diff_ex intersection_ex offset offset2);
+use Slic3r::Geometry::Clipper qw(union union_ex diff diff_ex intersection_ex offset offset2);
 use Slic3r::Surface ':types';
 
 
@@ -58,28 +58,26 @@ sub make_fill {
     # in case of bridge surfaces, the ones with defined angle will be attached to the ones
     # without any angle (shouldn't this logic be moved to process_external_surfaces()?)
     {
-        my @fill_surfaces = @{$layerm->fill_surfaces};
-        my @surfaces_with_bridge_angle = grep defined $_->bridge_angle, @fill_surfaces;
+        my @surfaces_with_bridge_angle = grep defined $_->bridge_angle, @{$layerm->fill_surfaces};
         
         # give priority to bridges
-        my @groups = Slic3r::Surface->group({merge_solid => 1}, @fill_surfaces);
-        @groups = sort { defined $a->[0]->bridge_angle ? -1 : 0 } @groups;
+        my @groups = sort { defined $a->[0]->bridge_angle ? -1 : 0 } @{$layerm->fill_surfaces->group(1)};
         
         foreach my $group (@groups) {
-            my $union = union_ex([ map $_->p, @$group ], 1);
+            my $union_p = union([ map $_->p, @$group ], 1);
             
             # subtract surfaces having a defined bridge_angle from any other
             if (@surfaces_with_bridge_angle && !defined $group->[0]->bridge_angle) {
-                $union = diff_ex(
-                    [ map @$_, @$union ],
+                $union_p = diff(
+                    $union_p,
                     [ map $_->p, @surfaces_with_bridge_angle ],
                     1,
                 );
             }
             
             # subtract any other surface already processed
-            $union = diff_ex(
-                [ map @$_, @$union ],
+            my $union = diff_ex(
+                $union_p,
                 [ map $_->p, @surfaces ],
                 1,
             );
diff --git a/lib/Slic3r/Layer/Region.pm b/lib/Slic3r/Layer/Region.pm
index 4f95f6518..e264bfe5f 100644
--- a/lib/Slic3r/Layer/Region.pm
+++ b/lib/Slic3r/Layer/Region.pm
@@ -458,7 +458,7 @@ sub process_external_surfaces {
     
     # intersect the grown surfaces with the actual fill boundaries
     my @new_surfaces = ();
-    foreach my $group (Slic3r::Surface->group(@top, @bottom)) {
+    foreach my $group (@{Slic3r::Surface::Collection->new(@top, @bottom)->group}) {
         push @new_surfaces,
             map $group->[0]->clone(expolygon => $_),
             @{intersection_ex(
@@ -470,7 +470,7 @@ sub process_external_surfaces {
     
     # subtract the new top surfaces from the other non-top surfaces and re-add them
     my @other = grep $_->surface_type != S_TYPE_TOP && $_->surface_type != S_TYPE_BOTTOM, @surfaces;
-    foreach my $group (Slic3r::Surface->group(@other)) {
+    foreach my $group (@{Slic3r::Surface::Collection->new(@other)->group}) {
         push @new_surfaces, map $group->[0]->clone(expolygon => $_), @{diff_ex(
             [ map $_->p, @$group ],
             [ map $_->p, @new_surfaces ],
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index 17504d7b9..dcca3c5b2 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -487,7 +487,7 @@ sub bridge_over_infill {
                     foreach my $lower_layerm (@{$self->layers->[$i]->regions}) {
                         my @new_surfaces = ();
                         # subtract the area from all types of surfaces
-                        foreach my $group (Slic3r::Surface->group(@{$lower_layerm->fill_surfaces})) {
+                        foreach my $group (@{$lower_layerm->fill_surfaces->group}) {
                             push @new_surfaces, map $group->[0]->clone(expolygon => $_),
                                 @{diff_ex(
                                     [ map $_->p, @$group ],
@@ -647,7 +647,7 @@ sub discover_horizontal_shells {
                         (expolygon => $_, surface_type => S_TYPE_INTERNALSOLID), @$internal_solid);
                     
                     # assign top and bottom surfaces to layer
-                    foreach my $s (Slic3r::Surface->group(grep { ($_->surface_type == S_TYPE_TOP) || ($_->surface_type == S_TYPE_BOTTOM) } @neighbor_fill_surfaces)) {
+                    foreach my $s (@{Slic3r::Surface::Collection->new(grep { ($_->surface_type == S_TYPE_TOP) || ($_->surface_type == S_TYPE_BOTTOM) } @neighbor_fill_surfaces)->group}) {
                         my $solid_surfaces = diff_ex(
                             [ map $_->p, @$s ],
                             [ map @$_, @$internal_solid, @$internal ],
diff --git a/lib/Slic3r/Surface.pm b/lib/Slic3r/Surface.pm
index e1b84ad5a..998645a10 100644
--- a/lib/Slic3r/Surface.pm
+++ b/lib/Slic3r/Surface.pm
@@ -7,26 +7,6 @@ our @ISA = qw(Exporter);
 our @EXPORT_OK   = qw(S_TYPE_TOP S_TYPE_BOTTOM S_TYPE_INTERNAL S_TYPE_INTERNALSOLID S_TYPE_INTERNALBRIDGE S_TYPE_INTERNALVOID);
 our %EXPORT_TAGS = (types => \@EXPORT_OK);
 
-# static method to group surfaces having same surface_type, bridge_angle and thickness*
-sub group {
-    my $class = shift;
-    my $params = ref $_[0] eq 'HASH' ? shift(@_) : {};
-    my (@surfaces) = @_;
-    
-    my %unique_types = ();
-    foreach my $surface (@surfaces) {
-        my $type = join '_',
-            ($params->{merge_solid} && $surface->is_solid) ? 'solid' : $surface->surface_type,
-            $surface->bridge_angle // '',
-            $surface->thickness // '',
-            $surface->thickness_layers;
-        $unique_types{$type} ||= [];
-        push @{ $unique_types{$type} }, $surface;
-    }
-    
-    return values %unique_types;
-}
-
 sub offset {
     my $self = shift;
     return [ map $self->clone(expolygon => $_), @{$self->expolygon->offset_ex(@_)} ];
diff --git a/xs/MANIFEST b/xs/MANIFEST
index 9d2e3699e..5256bba42 100644
--- a/xs/MANIFEST
+++ b/xs/MANIFEST
@@ -20,6 +20,8 @@ src/ExtrusionEntity.cpp
 src/ExtrusionEntity.hpp
 src/ExtrusionEntityCollection.cpp
 src/ExtrusionEntityCollection.hpp
+src/Geometry.cpp
+src/Geometry.hpp
 src/Line.cpp
 src/Line.hpp
 src/MultiPoint.cpp
@@ -55,12 +57,14 @@ t/10_line.t
 t/11_clipper.t
 t/12_extrusionpathcollection.t
 t/13_polylinecollection.t
+t/14_geometry.t
 xsp/Clipper.xsp
 xsp/ExPolygon.xsp
 xsp/ExPolygonCollection.xsp
 xsp/ExtrusionEntityCollection.xsp
 xsp/ExtrusionLoop.xsp
 xsp/ExtrusionPath.xsp
+xsp/Geometry.xsp
 xsp/Line.xsp
 xsp/my.map
 xsp/mytype.map
diff --git a/xs/src/Surface.cpp b/xs/src/Surface.cpp
index fadb47213..085756b86 100644
--- a/xs/src/Surface.cpp
+++ b/xs/src/Surface.cpp
@@ -30,6 +30,13 @@ Surface::to_SV_ref() {
     sv_setref_pv( sv, "Slic3r::Surface::Ref", (void*)this );
     return sv;
 }
+
+SV*
+Surface::to_SV_clone_ref() const {
+    SV* sv = newSV(0);
+    sv_setref_pv( sv, "Slic3r::Surface", new Surface(*this) );
+    return sv;
+}
 #endif
 
 }
diff --git a/xs/src/Surface.hpp b/xs/src/Surface.hpp
index 5c4d65ef2..304cc4572 100644
--- a/xs/src/Surface.hpp
+++ b/xs/src/Surface.hpp
@@ -22,10 +22,12 @@ class Surface
     
     #ifdef SLIC3RXS
     SV* to_SV_ref();
+    SV* to_SV_clone_ref() const;
     #endif
 };
 
 typedef std::vector<Surface> Surfaces;
+typedef std::vector<Surface*> SurfacesPtr;
 
 }
 
diff --git a/xs/src/SurfaceCollection.cpp b/xs/src/SurfaceCollection.cpp
index 898db92e1..ce4995eae 100644
--- a/xs/src/SurfaceCollection.cpp
+++ b/xs/src/SurfaceCollection.cpp
@@ -21,12 +21,12 @@ SurfaceCollection::simplify(double tolerance)
 
 /* group surfaces by common properties */
 void
-SurfaceCollection::group(std::vector<Surfaces> &retval, bool merge_solid) const
+SurfaceCollection::group(std::vector<SurfacesPtr> &retval, bool merge_solid)
 {
-    typedef std::map<t_surface_group_key,Surfaces> t_unique_map;
+    typedef std::map<t_surface_group_key,SurfacesPtr> t_unique_map;
     t_unique_map unique_map;
     
-    for (Surfaces::const_iterator it = this->surfaces.begin(); it != this->surfaces.end(); ++it) {
+    for (Surfaces::iterator it = this->surfaces.begin(); it != this->surfaces.end(); ++it) {
         // build the t_surface_group_key struct with this surface's properties
         t_surface_group_key key;
         if (merge_solid && it->is_solid()) {
@@ -41,9 +41,9 @@ SurfaceCollection::group(std::vector<Surfaces> &retval, bool merge_solid) const
         // check whether we already have a group for these properties
         if (unique_map.find(key) == unique_map.end()) {
             // no group exists, add it
-            unique_map[key] = Surfaces();
+            unique_map[key] = SurfacesPtr();
         }
-        unique_map[key].push_back(*it);
+        unique_map[key].push_back(&*it);
     }
     
     retval.reserve(unique_map.size());
diff --git a/xs/src/SurfaceCollection.hpp b/xs/src/SurfaceCollection.hpp
index e941cee21..32bd6c042 100644
--- a/xs/src/SurfaceCollection.hpp
+++ b/xs/src/SurfaceCollection.hpp
@@ -25,7 +25,7 @@ class SurfaceCollection
     public:
     Surfaces surfaces;
     void simplify(double tolerance);
-    void group(std::vector<Surfaces> &retval, bool merge_solid = false) const;
+    void group(std::vector<SurfacesPtr> &retval, bool merge_solid = false);
 };
 
 }
diff --git a/xs/t/05_surface.t b/xs/t/05_surface.t
index 4a3689bee..493a74b52 100644
--- a/xs/t/05_surface.t
+++ b/xs/t/05_surface.t
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 14;
+use Test::More tests => 16;
 
 my $square = [  # ccw
     [100, 100],
@@ -63,4 +63,15 @@ is $surface->extra_perimeters, 2, 'extra_perimeters';
     is $item->surface_type, $collection->[0]->surface_type, 'collection returns items by reference';
 }
 
+{
+    my @surfaces = (
+        Slic3r::Surface->new(expolygon => $expolygon, surface_type => Slic3r::Surface::S_TYPE_BOTTOM),
+        Slic3r::Surface->new(expolygon => $expolygon, surface_type => Slic3r::Surface::S_TYPE_BOTTOM),
+        Slic3r::Surface->new(expolygon => $expolygon, surface_type => Slic3r::Surface::S_TYPE_TOP),
+    );
+    my $collection = Slic3r::Surface::Collection->new(@surfaces);
+    is scalar(@{$collection->group}), 2, 'group() returns correct number of groups';
+    is scalar(@{$collection->group(1)}), 1, 'group() returns correct number of solid groups';
+}
+
 __END__
diff --git a/xs/xsp/SurfaceCollection.xsp b/xs/xsp/SurfaceCollection.xsp
index e8ecd0028..d880ebcdb 100644
--- a/xs/xsp/SurfaceCollection.xsp
+++ b/xs/xsp/SurfaceCollection.xsp
@@ -74,5 +74,30 @@ SurfaceCollection::set_surface_type(index, surface_type)
     CODE:
         THIS->surfaces[index].surface_type = surface_type;
 
+SV*
+SurfaceCollection::group(merge_solid = false)
+    bool    merge_solid
+    CODE:
+        // perform grouping
+        std::vector<SurfacesPtr> groups;
+        THIS->group(groups, merge_solid);
+        
+        // build return arrayref
+        AV* av = newAV();
+        av_fill(av, groups.size()-1);
+        size_t i = 0;
+        for (std::vector<SurfacesPtr>::iterator it = groups.begin(); it != groups.end(); ++it) {
+            AV* innerav = newAV();
+            av_fill(innerav, it->size()-1);
+            size_t j = 0;
+            for (SurfacesPtr::iterator it_s = it->begin(); it_s != it->end(); ++it_s) {
+                av_store(innerav, j++, (*it_s)->to_SV_clone_ref());
+            }
+            av_store(av, i++, newRV_noinc((SV*)innerav));
+        }
+        RETVAL = newRV_noinc((SV*)av);
+    OUTPUT:
+        RETVAL
+
 %}
 };