How to fix color change in models due to upgrade in gazebo ?

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I recently upgraded my Gazebo from 2 to 7, Everything works seamlessly except for my models which I built when I was using gazebo 2. The models were all white with amorphous shapes but after upgrade I dont see some of the edges of my models and some of them have turned black. has anyone else ran into this problem ? is there any fix or should I go back and build the collada files with sketchup and rebuild everything . Thank you