The meaning of 'distance' in rendering_metadata.txt?

[yeweining]

Hi Author, what is the specific meaning of 'distance' (range from 0~1) in rendering_metadata.txt, and what is the definition of the center of the voxel?
In other words, how can I get the coordinates of the viewpoint from the 32*32*32 voxel and the annotations in rendering_metadata.txt?
Thank you so much!