diff --git a/l5kit/l5kit/data/map_api.py b/l5kit/l5kit/data/map_api.py
index 6811f20a..18947491 100644
--- a/l5kit/l5kit/data/map_api.py
+++ b/l5kit/l5kit/data/map_api.py
@@ -110,7 +110,7 @@ def get_lane_coords(self, element_id: str) -> dict:
             element_id (str): lane element id
 
         Returns:
-            dict: a dict with the two boundaries coordinates as (Nx3) XYZ arrays
+            dict: a dict with the boundaries coordinates as (3xN) XYZ arrays
         """
         element = self[element_id]
         assert self.is_lane(element)
@@ -132,7 +132,10 @@ def get_lane_coords(self, element_id: str) -> dict:
             lane.geo_frame,
         )
 
-        return {"xyz_left": xyz_left, "xyz_right": xyz_right}
+        xyz = np.vstack((xyz_left, np.flip(xyz_right, 0)))
+        xyz[:, -1] = 1.0
+
+        return {"xyz": xyz.T}
 
     @staticmethod
     @no_type_check
@@ -161,7 +164,7 @@ def get_crosswalk_coords(self, element_id: str) -> dict:
             element_id (str): crosswalk element id
 
         Returns:
-            dict: a dict with the polygon coordinates as an (Nx3) XYZ array
+            dict: a dict with the polygon coordinates as an (3xN) XYZ array
         """
         element = self[element_id]
         assert self.is_crosswalk(element)
@@ -174,7 +177,8 @@ def get_crosswalk_coords(self, element_id: str) -> dict:
             traffic_element.geo_frame,
         )
 
-        return {"xyz": xyz}
+        xyz[:, -1] = 1.0
+        return {"xyz": xyz.T}
 
     def is_traffic_face_colour(self, element_id: str, colour: str) -> bool:
         """
diff --git a/l5kit/l5kit/rasterization/semantic_rasterizer.py b/l5kit/l5kit/rasterization/semantic_rasterizer.py
index 5f728462..d82f9724 100644
--- a/l5kit/l5kit/rasterization/semantic_rasterizer.py
+++ b/l5kit/l5kit/rasterization/semantic_rasterizer.py
@@ -6,7 +6,7 @@
 
 from ..data.filter import filter_tl_faces_by_status
 from ..data.map_api import MapAPI
-from ..geometry import rotation33_as_yaw, transform_point, transform_points, world_to_image_pixels_matrix
+from ..geometry import rotation33_as_yaw, transform_point, world_to_image_pixels_matrix
 from .rasterizer import Rasterizer
 
 # sub-pixel drawing precision constants
@@ -95,20 +95,20 @@ def get_bounds(self) -> dict:
 
             if self.proto_API.is_lane(element):
                 lane = self.proto_API.get_lane_coords(element_id)
-                x_min = min(np.min(lane["xyz_left"][:, 0]), np.min(lane["xyz_right"][:, 0]))
-                y_min = min(np.min(lane["xyz_left"][:, 1]), np.min(lane["xyz_right"][:, 1]))
-                x_max = max(np.max(lane["xyz_left"][:, 0]), np.max(lane["xyz_right"][:, 0]))
-                y_max = max(np.max(lane["xyz_left"][:, 1]), np.max(lane["xyz_right"][:, 1]))
+                x_min = np.min(lane["xyz"][0, :])
+                y_min = np.min(lane["xyz"][1, :])
+                x_max = np.max(lane["xyz"][0, :])
+                y_max = np.max(lane["xyz"][1, :])
 
                 lanes_bounds = np.append(lanes_bounds, np.asarray([[[x_min, y_min], [x_max, y_max]]]), axis=0)
                 lanes_ids.append(element_id)
 
             if self.proto_API.is_crosswalk(element):
                 crosswalk = self.proto_API.get_crosswalk_coords(element_id)
-                x_min = np.min(crosswalk["xyz"][:, 0])
-                y_min = np.min(crosswalk["xyz"][:, 1])
-                x_max = np.max(crosswalk["xyz"][:, 0])
-                y_max = np.max(crosswalk["xyz"][:, 1])
+                x_min = np.min(crosswalk["xyz"][0, :])
+                y_min = np.min(crosswalk["xyz"][1, :])
+                x_max = np.max(crosswalk["xyz"][0, :])
+                y_max = np.max(crosswalk["xyz"][1, :])
 
                 crosswalks_bounds = np.append(
                     crosswalks_bounds, np.asarray([[[x_min, y_min], [x_max, y_max]]]), axis=0,
@@ -176,12 +176,10 @@ def render_semantic_map(
 
             # get image coords
             lane_coords = self.proto_API.get_lane_coords(self.bounds_info["lanes"]["ids"][idx])
-            xy_left = cv2_subpixel(transform_points(lane_coords["xyz_left"][:, :2], world_to_image_space))
-            xy_right = cv2_subpixel(transform_points(lane_coords["xyz_right"][:, :2], world_to_image_space))
-            lanes_area = np.vstack((xy_left, np.flip(xy_right, 0)))  # start->end left then end->start right
+            lanes_xy = cv2_subpixel(world_to_image_space.dot(lane_coords["xyz"]).T[:, :2])
 
             # Note(lberg): this called on all polygons skips some of them, don't know why
-            cv2.fillPoly(img, [lanes_area], (17, 17, 31), lineType=cv2.LINE_AA, shift=CV2_SHIFT)
+            cv2.fillPoly(img, [lanes_xy], (17, 17, 31), lineType=cv2.LINE_AA, shift=CV2_SHIFT)
 
             lane_type = "default"  # no traffic light face is controlling this lane
             lane_tl_ids = set([MapAPI.id_as_str(la_tc) for la_tc in lane.traffic_controls])
@@ -193,7 +191,7 @@ def render_semantic_map(
                 elif self.proto_API.is_traffic_face_colour(tl_id, "yellow"):
                     lane_type = "yellow"
 
-            lanes_lines[lane_type].extend([xy_left, xy_right])
+            lanes_lines[lane_type].extend([lanes_xy])
 
         cv2.polylines(img, lanes_lines["default"], False, (255, 217, 82), lineType=cv2.LINE_AA, shift=CV2_SHIFT)
         cv2.polylines(img, lanes_lines["green"], False, (0, 255, 0), lineType=cv2.LINE_AA, shift=CV2_SHIFT)
@@ -205,7 +203,7 @@ def render_semantic_map(
         for idx in elements_within_bounds(center_world, self.bounds_info["crosswalks"]["bounds"], raster_radius):
             crosswalk = self.proto_API.get_crosswalk_coords(self.bounds_info["crosswalks"]["ids"][idx])
 
-            xy_cross = cv2_subpixel(transform_points(crosswalk["xyz"][:, :2], world_to_image_space))
+            xy_cross = cv2_subpixel(world_to_image_space.dot(crosswalk["xyz"]).T[:, :2])
             crosswalks.append(xy_cross)
 
         cv2.polylines(img, crosswalks, True, (255, 117, 69), lineType=cv2.LINE_AA, shift=CV2_SHIFT)