We can insert a primitive shape in to a link, or we can insert a mesh file using the mesh tag. The following example shows how to insert a mesh into the vision sensor:
<visual> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <mesh filename= "package://mastering_ros_robot_description_pkg/meshes/sensors/xtion_pro_live/xtion_pro_live.dae"/> </geometry> <material name="DarkGrey"/> </visual>