diff --git a/.travis.yml b/.travis.yml
index bd8ee237d..3bc267665 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -71,7 +71,6 @@ install:
 - source activate test-environment
 # make sure we parked our car in the right spot
 - python -c "import os,sys;assert '{}.{}'.format(*sys.version_info[:2])==os.environ['PYTHON_VERSION']"
-
 # only install the basic version of the library to make sure
 # trimesh imports and functions with only the minimal install
 - pip install .
@@ -103,6 +102,8 @@ script:
 - if [[ "$PYTHON_VERSION" == "3.6" ]]; then pip install python-fcl; fi;
 # lxml stopped supporting EOL Python
 - if [[ "$PYTHON_VERSION" == "3.4" ]]; then pip install lxml==4.3.5; fi;
+# sdist for released shapely has issues on 3.8
+- if [[ "$PYTHON_VERSION" == "3.8" ]]; then pip install shapely==1.7a2; fi;
 
 # install most deps here
 - pip install -q .[easy]
diff --git a/docker/builds/apt.bash b/docker/builds/apt.bash
index 64dc2d97d..df4f0c06b 100644
--- a/docker/builds/apt.bash
+++ b/docker/builds/apt.bash
@@ -2,7 +2,7 @@ set -xe
 apt-get update -qq
 apt-get upgrade -y -qq --no-install-recommends
 apt-get install -y -qq --no-install-recommends wget bzip2 supervisor \
-	libgl1-mesa-glx libgl1-mesa-dri xvfb xauth libgeos-dev libspatialindex-c5 \
+	libgl1-mesa-glx libgl1-mesa-dri xvfb xauth \
 	libassimp-dev ca-certificates zstd unzip \
 	freeglut3-dev
 
diff --git a/docker/builds/conda.bash b/docker/builds/conda.bash
index a30af25da..a584b6cff 100644
--- a/docker/builds/conda.bash
+++ b/docker/builds/conda.bash
@@ -19,7 +19,7 @@ conda config --add channels conda-forge
 # pyembree is used for fast ray tests
 # this will also install numpy from conda
 # conda/numpy is compiled with intel's MKL
-conda install pyembree 
+conda install pyembree rtree
 
 # install trimesh from the repo
 cd /tmp/trimesh
diff --git a/tests/test_export.py b/tests/test_export.py
index 1a6a58d6d..2b3909b90 100644
--- a/tests/test_export.py
+++ b/tests/test_export.py
@@ -16,7 +16,7 @@ def test_export(self):
 
         for mesh in meshes:
             # disregard texture
-            mesh.merge_vertices(textured=False)
+            mesh.merge_vertices(merge_tex=True, merge_norm=True)
             for file_type in export_types:
                 # skip pointcloud format
                 if file_type in ['xyz', 'gltf']:
@@ -50,7 +50,10 @@ def test_export(self):
                     file_obj = export
 
                 loaded = g.trimesh.load(file_obj=file_obj,
-                                        file_type=file_type)
+                                        file_type=file_type,
+                                        process=True,
+                                        merge_norm=True,
+                                        merge_tex=True)
 
                 # if we exported as GLTF/dae it will come back as a Scene
                 if isinstance(loaded, g.trimesh.Scene) and isinstance(
diff --git a/tests/test_gltf.py b/tests/test_gltf.py
index 1a3c78b55..be108e449 100644
--- a/tests/test_gltf.py
+++ b/tests/test_gltf.py
@@ -28,7 +28,7 @@ def test_duck(self):
         g.scene_equal(scene, reloaded)
 
         # if we merge ugly it should now be watertight
-        geom.merge_vertices(textured=False)
+        geom.merge_vertices(merge_tex=True)
         assert geom.is_volume
 
     def test_tex_export(self):
@@ -217,6 +217,30 @@ def test_node_name(self):
         assert (set(s.graph.nodes_geometry) ==
                 set(r.graph.nodes_geometry))
 
+    def test_schema(self):
+        # get a copy of the GLTF schema and do simple checks
+        s = g.trimesh.exchange.gltf.get_schema()
+
+        # make sure it has at least the keys we expect
+        assert set(s['properties'].keys()).issuperset(
+            {'accessors',
+             'animations',
+             'asset',
+             'buffers',
+             'bufferViews',
+             'cameras',
+             'images',
+             'materials',
+             'meshes',
+             'nodes',
+             'samplers',
+             'scene',
+             'scenes',
+             'skins',
+             'textures',
+             'extensions',
+             'extras'})
+
 
 if __name__ == '__main__':
     g.trimesh.util.attach_to_log()
diff --git a/tests/test_normals.py b/tests/test_normals.py
index 8d70fbbe5..45af8d455 100644
--- a/tests/test_normals.py
+++ b/tests/test_normals.py
@@ -159,7 +159,7 @@ def test_merge(self):
         assert g.np.isclose(m.volume, 8.0, atol=1e-4)
 
         # without considering normals should just be cube
-        m.merge_vertices(use_norm=False)
+        m.merge_vertices(merge_norm=True)
         assert m.vertices.shape == (8, 3)
         assert m.faces.shape == (12, 3)
         assert g.np.isclose(m.volume, 8.0, atol=1e-4)
diff --git a/tests/test_paths.py b/tests/test_paths.py
index 7b33cdf02..8ff8221d5 100644
--- a/tests/test_paths.py
+++ b/tests/test_paths.py
@@ -7,15 +7,6 @@
 class VectorTests(g.unittest.TestCase):
 
     def test_discrete(self):
-        try:
-            # TODO : REMOVE THIS WHEN SHAPELY WORKS IN 3.8
-            from shapely import vectorized  # noqa
-            vec_ok = True
-        except BaseException:
-            vec_ok = False
-            g.log.error(
-                'no shapely.vectorized!', exc_info=True)
-
         for d in g.get_2D():
             # store md5 before requesting passive functions
             md5 = d.md5()
@@ -108,7 +99,7 @@ def test_discrete(self):
             # Y should not have moved
             assert g.np.allclose(d.bounds[:, 1], ori[:, 1])
 
-            if vec_ok and len(d.polygons_full) > 0 and len(d.vertices) < 150:
+            if len(d.polygons_full) > 0 and len(d.vertices) < 150:
                 g.log.info('Checking medial axis on %s',
                            d.metadata['file_name'])
                 m = d.medial_axis()
@@ -239,13 +230,6 @@ def test_sample(self):
         """
         Test random sampling of polygons
         """
-        try:
-            # TODO : REMOVE THIS
-            from shapely import vectorized  # noqa
-        except BaseException:
-            g.log.error(
-                'no shapely.vectorized!', exc_info=True)
-            return
 
         p = g.Point([0, 0]).buffer(1.0)
         count = 100
diff --git a/trimesh/base.py b/trimesh/base.py
index 1bbf8a11c..f4ebc57ca 100644
--- a/trimesh/base.py
+++ b/trimesh/base.py
@@ -194,18 +194,17 @@ def __init__(self,
         # process will remove NaN and Inf values and merge vertices
         # if validate, will remove degenerate and duplicate faces
         if process or validate:
-            self.process()
+            self.process(validate=validate, **kwargs)
 
         # save reference to kwargs
         self._kwargs = kwargs
 
-    def process(self):
+    def process(self, **kwargs):
         """
         Do the bare minimum processing to make a mesh useful.
 
         Does this by:
             1) removing NaN and Inf values
-
             2) merging duplicate vertices
 
         If self._validate:
@@ -226,10 +225,10 @@ def process(self):
         # avoid clearing the cache during operations
         with self._cache:
             self.remove_infinite_values()
-            self.merge_vertices()
+            self.merge_vertices(**kwargs)
             # if we're cleaning remove duplicate
             # and degenerate faces
-            if self._validate:
+            if self._validate or ('validate' in kwargs and kwargs['validate']):
                 self.remove_duplicate_faces()
                 self.remove_degenerate_faces()
         # since none of our process operations moved vertices or faces
@@ -1101,9 +1100,9 @@ def merge_vertices(self, **kwargs):
           Number of digits to consider for UV coordinates
         """
         if 'textured' in kwargs:
-            kwargs['use_tex'] = kwargs.pop('textured')
+            kwargs['merge_tex'] = not kwargs.pop('textured')
             log.warning(
-                'merge_vertices depreciation: `textured`->`use_tex`')
+                'merge_vertices depreciation: `not textured`->`merge_tex`')
         grouping.merge_vertices(self, **kwargs)
 
     def update_vertices(self, mask, inverse=None):
@@ -1557,7 +1556,7 @@ def is_volume(self):
                      self.volume > 0.0)
         return valid
 
-    @caching.cache_decorator
+    @property
     def is_empty(self):
         """
         Does the current mesh have data defined.
@@ -1918,7 +1917,7 @@ def subdivide(self, face_index=None):
         return result
 
     @log_time
-    def smoothed(self, angle=None, facet_minlen=4):
+    def smoothed(self, **kwargs):
         """
         Return a version of the current mesh which will render
         nicely, without changing source mesh.
@@ -1928,8 +1927,10 @@ def smoothed(self, angle=None, facet_minlen=4):
         angle : float or None
           Angle in radians face pairs with angles
           smaller than this will appear smoothed
-        facet_minlen : int or None
-          Minimum length of facets to consider
+        facet_minarea : float or None
+          Minimum area fraction to consider
+          IE for `facets_minarea=25` only facets larger
+          than `mesh.area / 25` will be considered.
 
         Returns
         ---------
@@ -1945,9 +1946,7 @@ def smoothed(self, angle=None, facet_minlen=4):
             return cached
         # run smoothing
         smoothed = graph.smoothed(
-            self,
-            angle=angle,
-            facet_minlen=facet_minlen)
+            self, **kwargs)
         self.visual._cache['smoothed'] = smoothed
         return smoothed
 
diff --git a/trimesh/collision.py b/trimesh/collision.py
index 8b30cf041..fd0968eef 100644
--- a/trimesh/collision.py
+++ b/trimesh/collision.py
@@ -242,8 +242,11 @@ def set_transform(self, name, transform):
         else:
             raise ValueError('{} not in collision manager!'.format(name))
 
-    def in_collision_single(self, mesh, transform=None,
-                            return_names=False, return_data=False):
+    def in_collision_single(self,
+                            mesh,
+                            transform=None,
+                            return_names=False,
+                            return_data=False):
         """
         Check a single object for collisions against all objects in the
         manager.
@@ -265,10 +268,10 @@ def in_collision_single(self, mesh, transform=None,
         is_collision : bool
           True if a collision occurs and False otherwise
         names : set of str
-          The set of names of objects that collided with the
+          [OPTIONAL] The set of names of objects that collided with the
           provided one
         contacts : list of ContactData
-          All contacts detected
+          [OPTIONAL] All contacts detected
         """
         if transform is None:
             transform = np.eye(4)
diff --git a/trimesh/exchange/gltf.py b/trimesh/exchange/gltf.py
index 5c72edcdb..dea7601e5 100644
--- a/trimesh/exchange/gltf.py
+++ b/trimesh/exchange/gltf.py
@@ -1237,7 +1237,7 @@ def get_schema():
       A copy of the GLTF 2.0 schema without external references.
     """
     # replace references
-    from ..schemas import resolve_json
+    from ..schemas import resolve
     # get zip resolver to access referenced assets
     from ..visual.resolvers import ZipResolver
 
@@ -1247,11 +1247,13 @@ def get_schema():
     archive = util.decompress(util.wrap_as_stream(blob), 'zip')
     # get a resolver object for accessing the schema
     resolver = ZipResolver(archive)
-    # remove references to other files in the schema and load
-    schema = json.loads(
-        resolve_json(
-            resolver.get('glTF.schema.json').decode('utf-8'),
-            resolver=resolver))
+    # get a loaded dict from the base file
+    unresolved = json.loads(util.decode_text(
+        resolver.get('glTF.schema.json')))
+    # remove references to other files in the schema
+    schema = resolve(unresolved,
+                     resolver=resolver)
+
     return schema
 
 
diff --git a/trimesh/graph.py b/trimesh/graph.py
index f82b408ed..1f2e65ab7 100644
--- a/trimesh/graph.py
+++ b/trimesh/graph.py
@@ -760,7 +760,7 @@ def edges_to_coo(edges, count=None, data=None):
     return matrix
 
 
-def smoothed(mesh, angle, facet_minlen=4):
+def smoothed(mesh, angle=None, facet_minarea=15):
     """
     Return a non- watertight version of the mesh which
     will render nicely with smooth shading by
@@ -770,12 +770,13 @@ def smoothed(mesh, angle, facet_minlen=4):
     -----------
     mesh : trimesh.Trimesh
       Source geometry
-    angle : float
-      Angle in radians: adjacent faces
-      below this angle will be smoothed
-    facet_minlen : None or int
-      If specified will specially group facets
-      with more faces
+    angle : float or None
+      Angle in radians face pairs with angles
+      smaller than this will appear smoothed
+    facet_minarea : float or None
+      Minimum area fraction to consider
+      IE for `facets_minarea=25` only facets larger
+      than `mesh.area / 25` will be considered.
 
     Returns
     ---------
@@ -798,12 +799,14 @@ def smoothed(mesh, angle, facet_minlen=4):
     facets = []
     nodes = None
     # collect coplanar regions for smoothing
-    if facet_minlen is not None:
+    if facet_minarea is not None:
+        areas = mesh.area_faces
+        min_area = mesh.area / facet_minarea
         try:
             # we can survive not knowing facets
             # exclude facets with few faces
             facets = [f for f in mesh.facets
-                      if len(f) > facet_minlen]
+                      if areas[f].sum() > min_area]
             if len(facets) > 0:
                 # mask for removing adjacency pairs where
                 # one of the faces is contained in a facet
diff --git a/trimesh/grouping.py b/trimesh/grouping.py
index dff28ae44..bc77ca06c 100644
--- a/trimesh/grouping.py
+++ b/trimesh/grouping.py
@@ -21,25 +21,26 @@
 
 
 def merge_vertices(mesh,
-                   use_tex=True,
-                   use_norm=True,
+                   merge_tex=False,
+                   merge_norm=False,
                    digits_vertex=None,
                    digits_norm=2,
-                   digits_uv=4):
+                   digits_uv=4,
+                   **kwargs):
     """
-    Removes duplicate vertices based on integer hashes of
+    Removes duplicate vertices. By default,  based on integer hashes of
     each row.
 
     Parameters
     -------------
     mesh : Trimesh object
       Mesh to merge vertices on
-    use_tex : bool
-      If True for textured meshes merge vertices
-      with identical positions AND UV coordinates.
-    use_norm : bool
-      If True meshes with vertex normals defined will
-      only have vertices merged with identical normal
+    merge_tex : bool
+      If True textured meshes with UV coordinates will
+      have vertices merged regardless of UV coordinates
+    merge_norm : bool
+      If True, meshes with vertex normals will have
+      vertices merged ignoring different normals
     digits_vertex : None or int
       Number of digits to consider for vertex position
     digits_norm : int
@@ -60,25 +61,26 @@ def merge_vertices(mesh,
         # this is used for geometry without faces
         referenced = np.ones(len(mesh.vertices), dtype=np.bool)
 
-    # collect vertex attributes into sequence
+    # collect vertex attributes into sequence we can stack
     stacked = [mesh.vertices * (10 ** digits_vertex)]
 
     # UV texture visuals require us to update the
     # vertices and normals differently
-    if (use_tex and
+    if (not merge_tex and
         mesh.visual.defined and
         mesh.visual.kind == 'texture' and
-            mesh.visual.uv is not None):
+        mesh.visual.uv is not None and
+            len(mesh.visual.uv) == len(mesh.vertices)):
         # get an array with vertices and UV coordinates
         # converted to integers at requested precision
         stacked.append(mesh.visual.uv * (10 ** digits_uv))
 
     # check to see if we have vertex normals
     normals = mesh._cache['vertex_normals']
-    if use_norm and np.shape(normals) == np.shape(mesh.vertices):
+    if not merge_norm and np.shape(normals) == mesh.vertices.shape:
         stacked.append(normals * (10 ** digits_norm))
 
-    # stack collected vertex properties and round to int
+    # stack collected vertex properties and round to integer
     stacked = np.column_stack(stacked).round().astype(np.int64)
 
     # check unique rows of referenced vertices
diff --git a/trimesh/path/segments.py b/trimesh/path/segments.py
index d7c36e73b..c3c35eea0 100644
--- a/trimesh/path/segments.py
+++ b/trimesh/path/segments.py
@@ -11,6 +11,7 @@
 from .. import grouping
 from .. import geometry
 from .. import interval
+from .. import transformations
 
 from ..constants import tol
 
@@ -249,7 +250,7 @@ def unique(segments, digits=5):
     inverse.sort(axis=1)
     # remove segments where both indexes are the same
     mask = np.zeros(len(segments), dtype=np.bool)
-    # only include the first occurance of a segment
+    # only include the first occurrence of a segment
     mask[grouping.unique_rows(inverse)[0]] = True
     # remove segments that are zero-length
     mask[inverse[:, 0] == inverse[:, 1]] = False
@@ -509,7 +510,7 @@ def resample(segments,
     return result
 
 
-def to_svg(segments, digits=4, scale=None, origin=None):
+def to_svg(segments, digits=4, matrix=None):
     """
     Convert (n, 2, 2) line segments to an SVG path string.
 
@@ -519,10 +520,8 @@ def to_svg(segments, digits=4, scale=None, origin=None):
       Line segments to convert
     digits : int
       Number of digits to include in SVG string
-    scale : None or float
-      Scale to apply before exporting
-    origin : None or (2,) float
-      Origin to translate before scaling
+    matrix : None or (3, 3) float
+      Homogeneous 2D transformation to apply before export
 
     Returns
     -----------
@@ -530,19 +529,17 @@ def to_svg(segments, digits=4, scale=None, origin=None):
       SVG path string with one line per segment
       IE: 'M 0.1 0.2 L 10 12'
     """
-    segments = np.asanyarray(segments)
+    segments = np.array(segments, copy=True)
     if not util.is_shape(segments, (-1, 2, 2)):
         raise ValueError('only for (n, 2, 2) segments!')
 
     # create the array to export
-    flat = segments.copy().reshape((-1, 2))
-    # apply origin if passed
-    if origin is not None:
-        flat -= np.array(origin).reshape(2)
-    # then apply scale if passed
-    if scale is not None:
-        flat *= float(scale)
-    # create the base format for a single line segment
+    flat = segments.reshape((-1, 2))
+    # apply 2D transformation if passed
+    if matrix is not None:
+        flat = transformations.transform_points(
+            flat, matrix=matrix)
+    # create the format string for a single line segment
     base = ' M _ _ L _ _'.replace(
         '_', '{:0.' + str(int(digits)) + 'f}')
     # create one large format string then apply points
diff --git a/trimesh/resources/gltf_2_schema.zip b/trimesh/resources/gltf_2_schema.zip
index dc64d63e8..77ca496d2 100644
Binary files a/trimesh/resources/gltf_2_schema.zip and b/trimesh/resources/gltf_2_schema.zip differ
diff --git a/trimesh/schemas.py b/trimesh/schemas.py
index 932a756a3..d3180e1a5 100644
--- a/trimesh/schemas.py
+++ b/trimesh/schemas.py
@@ -6,78 +6,40 @@
 """
 import json
 
+from .util import decode_text
 
-def resolve_json(text, resolver, recursive=True, fill_empty='{}'):
+
+def resolve(item, resolver):
     """
-    Given a JSON Schema containing `$ref` keys, replace all
-    referenced URI values with their values using trimesh
-    Resolver objects.
+    Given a JSON Schema containing `$ref` keys recursively
+    evaluate to find and replace referenced files with their
+    actual values using trimesh.visual.Resolver objects.
 
     Parameters
     ---------------
-    text : str
-      JSON text including `$ref` to other files
+    item : any
+      JSON schema including `$ref` to other files
     resolver : trimesh.visual.resolver.Resolver
       Resolver to fetch referenced assets
-    recursive : bool
-      If True, resolve references in referenced files
-    fill_empty : str
-      What to replace empty references with
 
     Returns
     ----------
-    result : str
-      JSON text with references filled in
+    result : any
+      JSONSchema with references replaced
     """
-    if '$ref' not in text:
-        return text
-    # append strings to list then concatenate once
-    result = []
-    # set the current value to the input text
-    current = text
-    # loop with a for to cap iterations
-    for i in range(len(text)):
-        # find the referenced key in the text
-        idx = current.find('$ref')
-        # if the string wasn't found find will return -1
-        if idx < 0:
-            break
-        # find the first opening bracket before the ref key
-        first = current.rfind('{', 0, idx)
-        # find the first closing bracket after the ref key
-        last = current.find('}', idx)
-
-        # extract the URI of the reference
-        name = json.loads(current[first:last + 1])['$ref']
-
-        # get the bytes from the resolver
-        data = resolver.archive[name].read().decode('utf-8')
-
-        # include all text before the first reference
-        result.append(current[:first])
-
-        if recursive:
-            result.append(
-                resolve_json(
-                    data, resolver=resolver, recursive=True))
+    if isinstance(item, list):
+        # run the resolver on every list item
+        return [resolve(i, resolver) for i in item]
+    elif isinstance(item, dict):
+        if '$ref' in item:
+            # if we have a reference to a file pop the key
+            # and update the dict with the reference in-place
+            raw = decode_text(resolver.get(item.pop('$ref')))
+            item.update(json.loads(raw))
+            # run the resolver on the dict again
+            resolve(item, resolver)
         else:
-            # include the loaded data
-            result.append(data)
-
-        # if we had a reference to an empty file fill it
-        if len(result[-1].strip()) == 0:
-            result.append(fill_empty)
-
-        # for the next loop only look at the next chunk
-        current = current[last + 1:]
-
-    # any values after the last reference
-    result.append(current)
-
-    # append results into single string
-    appended = ' '.join(result)
-
-    # assert we got rid of all the references
-    assert '$ref' not in appended
-
-    return appended
+            # make sure all keys are evaluated
+            for i in item.values():
+                resolve(i, resolver)
+    return item
diff --git a/trimesh/version.py b/trimesh/version.py
index aa89269e5..89b1ca69d 100644
--- a/trimesh/version.py
+++ b/trimesh/version.py
@@ -1 +1 @@
-__version__ = '3.5.7'
+__version__ = '3.5.9'
diff --git a/trimesh/viewer/windowed.py b/trimesh/viewer/windowed.py
index 4b54dbb32..9fca737a0 100644
--- a/trimesh/viewer/windowed.py
+++ b/trimesh/viewer/windowed.py
@@ -24,7 +24,6 @@
 
 pyglet.options['shadow_window'] = False
 
-
 # smooth only when fewer faces than this
 _SMOOTH_MAX_FACES = 100000
 
@@ -45,6 +44,7 @@ def __init__(self,
                  offset_lines=True,
                  background=None,
                  window_conf=None,
+                 profile=False,
                  ** kwargs):
         """
         Create a window that will display a trimesh.Scene object
@@ -103,6 +103,11 @@ def __init__(self,
         self.batch = pyglet.graphics.Batch()
         self._smooth = smooth
 
+        self._profile = bool(profile)
+        if self._profile:
+            from pyinstrument import Profiler
+            self.Profiler = Profiler
+
         # store kwargs
         self.kwargs = kwargs
 
@@ -608,6 +613,10 @@ def on_draw(self):
         Run the actual draw calls.
         """
 
+        if self._profile:
+            profiler = self.Profiler()
+            profiler.start()
+
         self._update_meshes()
         gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
         gl.glLoadIdentity()
@@ -707,6 +716,10 @@ def on_draw(self):
             if texture is not None:
                 gl.glDisable(texture.target)
 
+        if self._profile:
+            profiler.stop()
+            print(profiler.output_text(unicode=True, color=True))
+
     def save_image(self, file_obj):
         """
         Save the current color buffer to a file object
diff --git a/trimesh/visual/resolvers.py b/trimesh/visual/resolvers.py
index 465049c34..21c2db55e 100644
--- a/trimesh/visual/resolvers.py
+++ b/trimesh/visual/resolvers.py
@@ -125,7 +125,9 @@ def get(self, name):
         # read file object from beginning
         obj.seek(0)
         # data is stored as a file object
-        return obj.read()
+        data = obj.read()
+        obj.seek(0)
+        return data
 
 
 class WebResolver(Resolver):