diff --git a/README.md b/README.md
index 8fd23fd..a2df45e 100644
--- a/README.md
+++ b/README.md
@@ -127,7 +127,7 @@ There are two examples which are implemented by LEGO (one of non-linear data fit
   **Run** 
   
   ```bash 
-  ./bin/example_pose_graph_lie_algebra ./lego/examples/pose_graph/sphere.g2o 0 
+  ./bin/example_pose_graph_lie_algebra ./lego/examples/pose_graph/sphere_with_noise.g2o 0 
   ```
 
   **Output** 
diff --git a/lego/examples/pose_graph/example_pose_graph_SE3.cpp b/lego/examples/pose_graph/example_pose_graph_SE3.cpp
index f43d505..0edd79b 100644
--- a/lego/examples/pose_graph/example_pose_graph_SE3.cpp
+++ b/lego/examples/pose_graph/example_pose_graph_SE3.cpp
@@ -146,7 +146,7 @@ class EdgeSE3 : public lego::BaseEdge {
 /// main
 int main(int argc, char **argv) {
     if (argc != 3) {
-        cout << "Usage: [RUN_FILE_example_pose_graph] [sphere.g2o] [STRATEGY_NO.] \nError: argc is not 3. " << endl;
+        cout << "Usage: [RUN_FILE_example_pose_graph] [sphere_with_noise.g2o] [STRATEGY_NO.] \nError: argc is not 3. " << endl;
         return 1;
     }
 
@@ -168,7 +168,7 @@ int main(int argc, char **argv) {
         problem.setStrategyType(lego::Problem::StrategyType::STRATEGY1);
         strategy_no = "1";
     } else {
-        std::cerr << "Usage: [RUN_FILE_example_pose_graph] [sphere.g2o] [STRATEGY_NO.] "
+        std::cerr << "Usage: [RUN_FILE_example_pose_graph] [sphere_with_noise.g2o] [STRATEGY_NO.] "
                   << "\nError: strategy index: " << argv[2] << " dose not exist. " << std::endl;
         return 2;
     }
diff --git a/lego/examples/pose_graph/example_pose_graph_lie_algebra.cpp b/lego/examples/pose_graph/example_pose_graph_lie_algebra.cpp
index 379697c..b7e50e2 100644
--- a/lego/examples/pose_graph/example_pose_graph_lie_algebra.cpp
+++ b/lego/examples/pose_graph/example_pose_graph_lie_algebra.cpp
@@ -147,7 +147,7 @@ class EdgeLieAlgebra : public lego::BaseEdge {
 /// main
 int main(int argc, char **argv) {
     if (argc != 3) {
-        cout << "Usage: [RUN_FILE_example_pose_graph] [sphere.g2o] [STRATEGY_NO.] \nError: argc is not 3. " << endl;
+        cout << "Usage: [RUN_FILE_example_pose_graph] [sphere_with_noise.g2o] [STRATEGY_NO.] \nError: argc is not 3. " << endl;
         return 1;
     }
 
@@ -169,7 +169,7 @@ int main(int argc, char **argv) {
         problem.setStrategyType(lego::Problem::StrategyType::STRATEGY1);
         strategy_no = "1";
     } else {
-        std::cerr << "Usage: [RUN_FILE_example_pose_graph] [sphere.g2o] [STRATEGY_NO.] "
+        std::cerr << "Usage: [RUN_FILE_example_pose_graph] [sphere_with_noise.g2o] [STRATEGY_NO.] "
                   << "\nError: strategy index: " << argv[2] << " dose not exist. " << std::endl;
         return 2;
     }
diff --git a/lego/examples/pose_graph/sphere.g2o b/lego/examples/pose_graph/sphere_with_noise.g2o
similarity index 100%
rename from lego/examples/pose_graph/sphere.g2o
rename to lego/examples/pose_graph/sphere_with_noise.g2o