diff --git a/Mapping/raycasting_grid_map/raycasting_grid_map.py b/Mapping/raycasting_grid_map/raycasting_grid_map.py
index 154c8fc2..c93ad7ed 100644
--- a/Mapping/raycasting_grid_map/raycasting_grid_map.py
+++ b/Mapping/raycasting_grid_map/raycasting_grid_map.py
@@ -1,6 +1,6 @@
 """
 
-2D grid map sample
+Ray casting 2D grid map example
 
 author: Atsushi Sakai (@Atsushi_twi)
 
@@ -9,46 +9,17 @@ author: Atsushi Sakai (@Atsushi_twi)
 import math
 import numpy as np
 import matplotlib.pyplot as plt
-from scipy.stats import norm
 
-AREA_WIDTH = 10.0
+EXTEND_AREA = 10.0
 
-STD = 10.0  # standard diviation
-
-
-def generate_gaussian_grid_map(ox, oy, xyreso):
-
-    minx, miny, maxx, maxy, xw, yw = calc_grid_map_config(ox, oy, xyreso)
-
-    # calc each potential
-    pmap = [[0.0 for i in range(yw)] for i in range(xw)]
-
-    for ix in range(xw):
-        for iy in range(yw):
-
-            x = ix * xyreso + minx
-            y = iy * xyreso + miny
-
-            # Search minimum distance
-            mindis = float("inf")
-            for (iox, ioy) in zip(ox, oy):
-                d = math.sqrt((iox - x)**2 + (ioy - y)**2)
-                if mindis >= d:
-                    mindis = d
-
-            pdf = (1.0 - norm.cdf(mindis, 0.0, STD))
-            pmap[ix][iy] = pdf
-
-    draw_heatmap(pmap, minx, maxx, miny, maxy, xyreso)
-    plt.plot(ox, oy, "xr")
-    plt.plot(0.0, 0.0, "ob")
+show_animation = True
 
 
 def calc_grid_map_config(ox, oy, xyreso):
-    minx = round(min(ox) - AREA_WIDTH / 2.0)
-    miny = round(min(oy) - AREA_WIDTH / 2.0)
-    maxx = round(max(ox) + AREA_WIDTH / 2.0)
-    maxy = round(max(oy) + AREA_WIDTH / 2.0)
+    minx = round(min(ox) - EXTEND_AREA / 2.0)
+    miny = round(min(oy) - EXTEND_AREA / 2.0)
+    maxx = round(max(ox) + EXTEND_AREA / 2.0)
+    maxy = round(max(oy) + EXTEND_AREA / 2.0)
     xw = int(round((maxx - minx) / xyreso))
     yw = int(round((maxy - miny) / xyreso))
 
@@ -69,6 +40,14 @@ class precastDB:
         return str(self.px) + "," + str(self.py) + "," + str(self.d) + "," + str(self.angle)
 
 
+def atan_zero_to_twopi(y, x):
+    angle = math.atan2(y, x)
+    if angle < 0.0:
+        angle += math.pi * 2.0
+
+    return angle
+
+
 def precasting(minx, miny, xw, yw, xyreso, yawreso):
 
     precast = [[] for i in range(round((math.pi * 2.0) / yawreso) + 1)]
@@ -79,10 +58,7 @@ def precasting(minx, miny, xw, yw, xyreso, yawreso):
             py = iy * xyreso + miny
 
             d = math.sqrt(px**2 + py**2)
-            angle = math.atan2(py, px)
-            if angle < 0.0:
-                angle += math.pi * 2.0
-
+            angle = atan_zero_to_twopi(py, px)
             angleid = math.floor(angle / yawreso)
 
             pc = precastDB()
@@ -99,23 +75,18 @@ def precasting(minx, miny, xw, yw, xyreso, yawreso):
     return precast
 
 
-def generate_ray_casting_grid_map(ox, oy, xyreso):
+def generate_ray_casting_grid_map(ox, oy, xyreso, yawreso):
 
     minx, miny, maxx, maxy, xw, yw = calc_grid_map_config(ox, oy, xyreso)
 
     pmap = [[0.0 for i in range(yw)] for i in range(xw)]
 
-    yawreso = math.radians(10.0)
-
     precast = precasting(minx, miny, xw, yw, xyreso, yawreso)
 
     for (x, y) in zip(ox, oy):
 
         d = math.sqrt(x**2 + y**2)
-        angle = math.atan2(y, x)
-        if angle < 0.0:
-            angle += math.pi * 2.0
-
+        angle = atan_zero_to_twopi(y, x)
         angleid = math.floor(angle / yawreso)
 
         gridlist = precast[angleid]
@@ -124,14 +95,12 @@ def generate_ray_casting_grid_map(ox, oy, xyreso):
         iy = int(round((y - miny) / xyreso))
 
         for grid in gridlist:
-            if grid.d > (d):
+            if grid.d > d:
                 pmap[grid.ix][grid.iy] = 0.5
 
         pmap[ix][iy] = 1.0
 
-    draw_heatmap(pmap, minx, maxx, miny, maxy, xyreso)
-    plt.plot(ox, oy, "xr")
-    plt.plot(0.0, 0.0, "ob")
+    return pmap, minx, maxx, miny, maxy, xyreso
 
 
 def draw_heatmap(data, minx, maxx, miny, maxy, xyreso):
@@ -144,18 +113,20 @@ def draw_heatmap(data, minx, maxx, miny, maxy, xyreso):
 def main():
     print(__file__ + " start!!")
 
-    xyreso = 0.5
+    xyreso = 0.25  # x-y grid resolution [m]
+    yawreso = math.radians(10.0)  # yaw angle resolution [rad]
 
     for i in range(5):
         ox = (np.random.rand(4) - 0.5) * 10.0
         oy = (np.random.rand(4) - 0.5) * 10.0
-        plt.cla()
-        generate_gaussian_grid_map(ox, oy, xyreso)
-        plt.pause(1.0)
-
-        plt.cla()
-        generate_ray_casting_grid_map(ox, oy, xyreso)
-        plt.pause(1.0)
+        pmap, minx, maxx, miny, maxy, xyreso = generate_ray_casting_grid_map(
+            ox, oy, xyreso, yawreso)
+        if show_animation:
+            plt.cla()
+            draw_heatmap(pmap, minx, maxx, miny, maxy, xyreso)
+            plt.plot(ox, oy, "xr")
+            plt.plot(0.0, 0.0, "ob")
+            plt.pause(1.0)
 
 
 if __name__ == '__main__':