(often called the "3D preview" or "perspective view" in older versions) works by taking the flat polygons on your mask layers and assigning them a height (Z-value) and a color . When you tilt the camera, you see "walls" rising from the substrate.
layout_view.update_3d_view
But what exactly is "2.5D"? It isn't true 3D rendering (like you’d see in Cadence Virtuoso 3D or Siemens Calibre 3DSTACK). Instead, the 2.5D view in KLayout gives you a pseudo-3D perspective where 2D polygons are extruded vertically based on layer information. This article dives deep into how to activate, configure, and leverage the KLayout 2.5D view to debug your designs faster than ever before. Before clicking buttons, let’s clarify the terminology. A true 3D view requires volume rendering (height, width, depth). KLayout does not natively do this because it is a layout tool, not a mechanical CAD tool. klayout 25d view