model data structure in vtk.js, please explain please help

Anyway to see the actualy data in a vtk object, e.g, imageData? the data must be somewhere stored in ‘model’, but it seems completely hidden from the chrome debugger by the publicAPIs. it is frustrating not being able to check the actual data. The publicAPI properties does not tell you anything about the object. So if I want to printout the data in imageData, what should I do?