diff --git a/.idea/libs.iml b/.idea/libs.iml
index 7d99385a..c268a131 100644
--- a/.idea/libs.iml
+++ b/.idea/libs.iml
@@ -6,7 +6,7 @@
       <excludeFolder url="file://$MODULE_DIR$/venv2" />
       <excludeFolder url="file://$MODULE_DIR$/venv38" />
     </content>
-    <orderEntry type="jdk" jdkName="Python 3.8 (libs) (2)" jdkType="Python SDK" />
+    <orderEntry type="jdk" jdkName="Python 3.7 (venv)" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
   <component name="PackageRequirementsSettings">
diff --git a/exports/exports_factory.py b/exports/exports_factory.py
index 04f2f9be..6a9d0216 100644
--- a/exports/exports_factory.py
+++ b/exports/exports_factory.py
@@ -7,6 +7,7 @@ Copyright © 2020 Project Author Guille Gutierrez guillermo.gutierrezmorote@conc
 from exports.formats.stl import Stl
 from exports.formats.obj import Obj
 
+
 class ExportsFactory:
   """
   Exports factory class
@@ -38,7 +39,7 @@ class ExportsFactory:
     Export the city geometry to obj
     :return: None
     """
-    return Obj(self._city, self._path)
+    return Obj(self._city, self._path).to_ground_points()
 
   @property
   def _idf(self):
diff --git a/exports/formats/obj.py b/exports/formats/obj.py
index 56e30706..f3f572ed 100644
--- a/exports/formats/obj.py
+++ b/exports/formats/obj.py
@@ -1,5 +1,25 @@
 from exports.formats.triangular import Triangular
+from pathlib import Path
+from imports.geometry_factory import GeometryFactory
+import trimesh.exchange.obj
+from trimesh import Trimesh
+
 
 class Obj(Triangular):
   def __init__(self, city, path):
     super().__init__(city, path, 'obj')
+
+  def to_ground_points(self):
+    reference_coordinates = self._city.lower_corner
+    file_name_in = self._city.name + '.' + self._triangular_format
+    file_name_out = self._city.name + '_ground.' + self._triangular_format
+    file_path_in = (Path(self._path).resolve() / file_name_in).resolve()
+    file_path_out = (Path(self._path).resolve() / file_name_out).resolve()
+    scene_dic = GeometryFactory('obj', file_path_in).scene
+    for vertex in scene_dic['vertices']:
+      for i in range(0, 3):
+        vertex[i] -= reference_coordinates[i]
+    scene = Trimesh(vertices=scene_dic['vertices'], faces=scene_dic['faces'])
+    obj_file = trimesh.exchange.obj.export_obj(scene)
+    with open(file_path_out, 'w') as file:
+      file.write(obj_file)
diff --git a/exports/formats/stl.py b/exports/formats/stl.py
index 915d455d..984c207a 100644
--- a/exports/formats/stl.py
+++ b/exports/formats/stl.py
@@ -1,5 +1,6 @@
 from exports.formats.triangular import Triangular
 
+
 class Stl(Triangular):
   def __init__(self, city, path):
     super().__init__(city, path, 'stl')
diff --git a/exports/formats/triangular.py b/exports/formats/triangular.py
index de5b9ec4..8a7b9dda 100644
--- a/exports/formats/triangular.py
+++ b/exports/formats/triangular.py
@@ -1,6 +1,7 @@
 from pathlib import Path
 from trimesh import Trimesh
 
+
 class Triangular:
   def __init__(self, city, path, triangular_format):
     self._city = city
diff --git a/imports/geometry_factory.py b/imports/geometry_factory.py
index a9c55d85..447a29fe 100644
--- a/imports/geometry_factory.py
+++ b/imports/geometry_factory.py
@@ -7,6 +7,7 @@ from city_model_structure.city import City
 from city_model_structure.city_object import CityObject
 from imports.geometry_feeders.city_gml import CityGml
 from imports.geometry_feeders.osm_subway import OsmSubway
+from imports.geometry_feeders.obj import Obj
 
 
 class GeometryFactory:
@@ -25,6 +26,10 @@ class GeometryFactory:
   def _stl(self):
     raise Exception('Not implemented')
 
+  @property
+  def _obj(self):
+    return Obj(self._path).scene
+
   @property
   def _geojson(self):
     raise Exception('Not implemented')
@@ -41,6 +46,14 @@ class GeometryFactory:
     """
     return getattr(self, self._file_type, lambda: None)
 
+  @property
+  def scene(self):
+    """
+    Load  the city model structure from a geometry source
+    :return: Trimesh
+    """
+    return getattr(self, self._file_type, lambda: None)
+
   @property
   def _city_debug(self):
     return CityGml(self._path).city
diff --git a/imports/geometry_feeders/obj.py b/imports/geometry_feeders/obj.py
new file mode 100644
index 00000000..fc82847a
--- /dev/null
+++ b/imports/geometry_feeders/obj.py
@@ -0,0 +1,21 @@
+"""
+Obj module parses obj files and import the geometry into the city model structure
+SPDX - License - Identifier: LGPL - 3.0 - or -later
+Copyright © 2020 Project Author Pilar Monsalvete Álvarez de Uribarri pilar.monsalvete@concordia.ca
+"""
+import trimesh.exchange.obj
+
+
+class Obj:
+  """
+  Obj class
+  """
+  def __init__(self, path):
+    self._city = None
+    with open(path, 'r') as file:
+      self._scene = trimesh.exchange.obj.load_obj(file)
+  # todo: review class trimesh.exchange.load that returns Trimesh or Trimesh.scene
+
+  @property
+  def scene(self) -> dict:
+    return self._scene
diff --git a/requirements.txt b/requirements.txt
index 24f9d4f4..638c0a1d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,10 +1,11 @@
 xmltodict~=0.12.0
 numpy~=1.20.1
-trimesh~=3.9.8
+trimesh~=3.9.9
 pyproj~=3.0.1
 pandas~=1.2.3
 requests~=2.25.1
 esoreader~=1.2.3
 geomeppy~=0.11.8
 open3d~=0.12.0
-pathlib~=1.0.1
\ No newline at end of file
+pathlib~=1.0.1
+PyWavefront~=1.3.3
\ No newline at end of file
diff --git a/tests/test_exports.py b/tests/test_exports.py
index 99ddb926..19ce1bb0 100644
--- a/tests/test_exports.py
+++ b/tests/test_exports.py
@@ -9,6 +9,7 @@ from unittest import TestCase
 from imports.geometry_factory import GeometryFactory
 from exports.exports_factory import ExportsFactory
 
+
 class TestExports(TestCase):
   """
   TestGeometryFactory TestCase 1