The x and y-direction objects must have the same number of points as the surface object. An easy way to ensure this is to create the x and y-direction objects by duplicating the surface curve using the Duplicate -> Immediate command. You can then reposition the copies and/or transform the control vertices of the duplicates before using the Duplicate -> Bridge effect in the Model module.
2. Choose Duplicate -> AnimatedBridge. The Bridge dialogue box is displayed.
3. Set the parameters as desired.
4. The effect prompts you to pick the surface, the y-direction model, the x-direction model, and the object to be duplicated.