Are you getting any error messages when loading the model?
If not, then it's most likely a scaling issue. The Vizard 5
Upgrade Guide mentions that Collada models will be automatically scaled to meters by default. You can disable this option by adding the following line to the beginning of your script, before any models are loaded:
Code:
viz.setOption('viz.model.apply_collada_scale', 0)
Try that and let us know if it doesn't solve the problem.