We tried to scan a sculpture and we placed it in front of a green screen and masked everything out so only the sculpture will be an alpha channel.
Then, after RC calculated the model an additional white chunk appeared which is not related to the original sculpture. We also noticed the only one side of the sculpture was scanned and the other sides were not.
We did take photos of the sculpture by rotating the sculpture and not rotating around the sculpture, though we did see a successful tutorial of that technique.
can you please switch the left-most panel to 1Ds and check how many components have been created? I suppose that RC could not merge all images together with the current settings and perhaps several chunks were created. Due to this, when you run the reconstruction, there are missing data from some angles and RC is enclosing the volume with large triangles there (RC creates watertight meshes).
Since your object is uni-color and featureless, you probably need to raise the alignment settings a little. Please try to change in the Alignment settings Detector sensitivity to High and also try to raise Max features per image and Preselector features (e.g. 60 000, 20 000 respectively).
you need to switch the left-most panel (in any layout with at least two views) to 1Ds to be able to see the number of created components. Only the left-most panel can be switched to 1Ds, it is a different view than 1D. You can find more information about these views in the Help – Get Familiar with the Application Basics.
If there are still some data missing from several angles, RC will fill the volume to make the model watertight. Once you check how many images were actually merged into one component, you will be able to see which images were not registered. You can place some control points on registered and unregistered images in order to merge them manually.