diff --git a/doc/pattern_tools/gen_pattern.py b/doc/pattern_tools/gen_pattern.py
index 3643b6d3b2..fc1e74bbc3 100755
--- a/doc/pattern_tools/gen_pattern.py
+++ b/doc/pattern_tools/gen_pattern.py
@@ -1,13 +1,19 @@
 #!/usr/bin/env python
 
 """gen_pattern.py
-To run:
--c 10 -r 12 -o out.svg
--T type of pattern, circles, acircles, checkerboard
--s --square_size size of squares in pattern
--u --units mm, inches, px, m
--w  page width in units
--h  page height in units
+Usage example:
+python gen_pattern.py -o out.svg -r 11 -c 8 -T circles -s 20.0 -R 5.0 -u mm -w 216 -h 279
+
+-o, --output - output file (default out.svg)
+-r, --rows - pattern rows (default 11)
+-c, --columns - pattern columns (default 8)
+-T, --type - type of pattern, circles, acircles, checkerboard (default circles)
+-s, --square_size - size of squares in pattern (default 20.0)
+-R, --radius_rate - circles_radius = square_size/radius_rate (default 5.0)
+-u, --units - mm, inches, px, m (default mm)
+-w, --page_width - page width in units (default 216)
+-h, --page_height - page height in units (default 279)
+-H, --help - show help
 """
 
 from svgfig import *
@@ -16,18 +22,20 @@ import sys
 import getopt
 
 class PatternMaker:
-  def __init__(self, cols,rows,output,units,square_size,page_width,page_height):
+  def __init__(self, cols,rows,output,units,square_size,radius_rate,page_width,page_height):
     self.cols = cols
     self.rows = rows
     self.output = output
     self.units = units
     self.square_size = square_size
+    self.radius_rate = radius_rate
     self.width = page_width
     self.height = page_height
     self.g = SVG("g") # the svg group container
+
   def makeCirclesPattern(self):
     spacing = self.square_size
-    r = spacing / 5.0 #radius is a 5th of the spacing TODO parameterize
+    r = spacing / self.radius_rate
     for x in range(1,self.cols+1):
       for y in range(1,self.rows+1):
         dot = SVG("circle", cx=x * spacing, cy=y * spacing, r=r, fill="black")
@@ -35,7 +43,7 @@ class PatternMaker:
 
   def makeACirclesPattern(self):
     spacing = self.square_size
-    r = spacing / 5.0
+    r = spacing / self.radius_rate
     for i in range(0,self.rows):
       for j in range(0,self.cols):
         dot = SVG("circle", cx= ((j*2 + i%2)*spacing) + spacing, cy=self.height - (i * spacing + spacing), r=r, fill="black")
@@ -43,37 +51,23 @@ class PatternMaker:
 
   def makeCheckerboardPattern(self):
     spacing = self.square_size
-    r = spacing / 5.0
     for x in range(1,self.cols+1):
       for y in range(1,self.rows+1):
-        #TODO make a checkerboard pattern
-        dot = SVG("circle", cx=x * spacing, cy=y * spacing, r=r, fill="black")
-        self.g.append(dot)
+        if x%2 == y%2:
+          dot = SVG("rect", x=x * spacing, y=y * spacing, width=spacing, height=spacing, stroke_width="0", fill="black")
+          self.g.append(dot)
+
   def save(self):
     c = canvas(self.g,width="%d%s"%(self.width,self.units),height="%d%s"%(self.height,self.units),viewBox="0 0 %d %d"%(self.width,self.height))
     c.inkview(self.output)
 
-def makePattern(cols,rows,output,p_type,units,square_size,page_width,page_height):
-    width = page_width
-    spacing = square_size
-    height = page_height
-    r = spacing / 5.0
-    g = SVG("g") # the svg group container
-    for x in range(1,cols+1):
-      for y in range(1,rows+1):
-        if "circle" in p_type:
-          dot = SVG("circle", cx=x * spacing, cy=y * spacing, r=r, fill="black")
-        g.append(dot)
-    c = canvas(g,width="%d%s"%(width,units),height="%d%s"%(height,units),viewBox="0 0 %d %d"%(width,height))
-    c.inkview(output)
-
 
 def main():
     # parse command line options, TODO use argparse for better doc
     try:
-        opts, args = getopt.getopt(sys.argv[1:], "ho:c:r:T:u:s:w:h:", ["help","output","columns","rows",
-                                                                      "type","units","square_size","page_width",
-                                                                      "page_height"])
+        opts, args = getopt.getopt(sys.argv[1:], "Ho:c:r:T:u:s:R:w:h:", ["help","output=","columns=","rows=",
+                                                                      "type=","units=","square_size=","radius_rate=",
+                                                                      "page_width=","page_height="])
     except getopt.error, msg:
         print msg
         print "for help use --help"
@@ -84,11 +78,12 @@ def main():
     p_type = "circles"
     units = "mm"
     square_size = 20.0
+    radius_rate = 5.0
     page_width = 216    #8.5 inches
     page_height = 279   #11 inches
     # process options
     for o, a in opts:
-        if o in ("-h", "--help"):
+        if o in ("-H", "--help"):
             print __doc__
             sys.exit(0)
         elif o in ("-r", "--rows"):
@@ -103,11 +98,13 @@ def main():
             units = a
         elif o in ("-s", "--square_size"):
             square_size = float(a)
+        elif o in ("-R", "--radius_rate"):
+            radius_rate = float(a)
         elif o in ("-w", "--page_width"):
             page_width = float(a)
         elif o in ("-h", "--page_height"):
             page_height = float(a)
-    pm = PatternMaker(columns,rows,output,units,square_size,page_width,page_height)
+    pm = PatternMaker(columns,rows,output,units,square_size,radius_rate,page_width,page_height)
     #dict for easy lookup of pattern type
     mp = {"circles":pm.makeCirclesPattern,"acircles":pm.makeACirclesPattern,"checkerboard":pm.makeCheckerboardPattern}
     mp[p_type]()