diff --git a/subt_ign/src/dot_generator.cc b/subt_ign/src/dot_generator.cc
index 16ac6f08..bce1a895 100644
--- a/subt_ign/src/dot_generator.cc
+++ b/subt_ign/src/dot_generator.cc
@@ -61,11 +61,12 @@ std::string parse(const std::string &_key, const std::string &_str)
 void printGraph(std::vector<VertexData> &_vertexData)
 {
   std::stringstream out;
+  out << "/* Visibility graph generated by dot_generator */\n\n";
   out << "graph {\n";
-  out << "/* ==== Vertices ==== */\n";
+  out << "  /* ==== Vertices ==== */\n\n";
 //  out << "0  [label=\"0::base_station::BaseStation\"]\n";
 
-  for (auto &vd : _vertexData)
+  for (const auto &vd : _vertexData)
   {
     // update staging area name for compatibility with other subt tools that
     // rely on this naming convention
@@ -77,11 +78,16 @@ void printGraph(std::vector<VertexData> &_vertexData)
       type = "base_station";
       name = "BaseStation";
     }
-    out << vd.id << "  " << "[label=\"" << vd.id << "::" << type
+    out << "  " << vd.id;
+    if (vd.id < 10)
+      out << " ";
+    out << "  " << "[label=\"" << vd.id << "::" << type
         << "::" << name << "\"];\n";
+    if (vd.id == 0)
+      out << std::endl;
   }
 
-  out << "/* ==== Edges ==== */\n";
+  out << "\n  /* ==== Edges ==== */\n\n";
 
   for (unsigned int i = 0u; i < _vertexData.size() -1; ++i)
   {
@@ -108,8 +114,13 @@ void printGraph(std::vector<VertexData> &_vertexData)
         else
           cost = 6;
 
-        out << _vertexData[i].id << " -- " << _vertexData[j].id
-            << " " << "[label=" << cost << "];\n";
+        out << "  " << _vertexData[i].id;
+        if (_vertexData[i].id < 10)
+         out <<  " ";
+        out << " -- " << _vertexData[j].id;
+        if (_vertexData[j].id < 10)
+         out <<  " ";
+        out << "  " << "[label=" << cost << "];\n";
       }
     }
   }
@@ -196,7 +207,7 @@ void generateDOT(const std::string &_sdfFile)
 //////////////////////////////////////////////////
 int main(int argc, char **argv)
 {
-  if (argc < 2)
+  if (argc != 2)
   {
     std::cerr << "Usage: dot_generator <path_to_world_sdf_file>"
               << std::endl;