Watch CGI is the closest thing to medical imaging that exists in the commercial world. We routinely model parts at 0.4mm across, with chamfers measured in single-digit microns. At that scale, traditional 3D conventions fall apart completely.
LIGHT BENDS DIFFERENTLY HERE
At sub-millimetre scale, the depth of field of any plausible camera collapses to nothing. We render with full physical camera simulations in Karma, including lens curvature, chromatic aberration, and the minute optical diffraction that occurs when light passes through an f/2.8 aperture near macro limits.
MATERIALS ARE NOT WHAT YOU THINK
Brushed steel at 50× magnification is not brushed steel. It is a forest of micro-grooves with their own micro-shadows. Every screw head carries tiny tooling marks from the CNC bit. If you leave those out, the watch looks sterile. If you add them with procedural noise, it looks dirty. The only solution is custom scan data and hand-painted roughness masks.
Haute horlogerie clients have spent two hundred years perfecting their hand-finishing. The least we can do is give their digital twins the same respect.