WriteData does not create a octree file to be shown using octovis

[reem90]

I used the writeData() function to create a map.ot file. The created file has redundant lines and when I tried to visualize it with octovis, I got an error says "can't open octree file". Also, when I used readData() function to load the map and visualize it with RVIZ all the voxels were white-colored. Could you please tell me the right way of calling these function? or What I am doing wrong?