Rectangular nesting is fast but wastes material with irregular parts. True-shape nesting places parts by their real outline.
The simplest way to arrange parts on a sheet is to treat each part as its bounding rectangle. It is quick and predictable – but irregular parts such as flanges, brackets or L-shaped profiles leave large unused areas between them.
What true-shape nesting does differently
True-shape nesting works with the actual contour of every part, including holes. For each pair of parts and orientations a No-Fit Polygon is computed: the exact region where one part may not be placed relative to the other. Parts can then interlock, small parts can go into the holes of large ones and concave shapes can be paired.
Rotation and mirroring
Allowing more rotation angles usually improves utilization, but increases computing time. In practice 90° steps are a good default, finer steps pay off for irregular parts. Mirroring should only be allowed where the front and back of the part do not matter.
The result must be safe
Arcs in the drawing are approximated by polygons for the calculation. SRSA NEST approximates them so that a part is never smaller than in the drawing, and checks the final layout for collisions, gaps and margins on the real geometry before export.