Hello Raymond,
You are correct in your observation that the shininess of the object is causing problem, since the specular reflection from a shiny surface is dependent on both the lighting and viewer direction, the bright specular area changes as the camera's view point changes as well. Similarly, the surrounding reflection on the shiny surface is also usually not static. (ie, the reflection of you holding the camera while capturing the object.)
Your second observation that the better reconstruction is confusingly on the metal parts and not the handle is twofold.
1) There are many blur spots of stain on metallic surface of the flask. Despite the high specular reflection, these spots serve as reasonably good features for the algorithm whenever they are not lost in the bright reflection.
2) The black handle while not metallic is still made of a very reflective plastic material hence it suffer from the same issue with any shiny surfaces. Compounding the issue is the general black color of the material, which just appears as a monotone featureless patch in most of the photos.
Our recommendation when attempting to capture shiny object are as below:
1) Choose a more diffuse/soft light source, this will reduce the bright specular reflection so you won't lose as much information on those area.
2) If you don't require the actual color but wants the accurate shape of the object. You can spray temporary matt paint to make the surface matt instead of shiny. Doing so will improve the reconstruction quality at the cost of losing color and possibly damaging the object.
A side note: We still don't recommend cropping or modifying the photos yourself, however you are free to experiment with it and let us know how it goes :).
Thanks for your interest and hope this might be helpful for you.
Naimin
