Tulip Stairs

Positioned beside the main hall the entire staircase runs 94 steps – including the lesser visible flight down to lower level. Each of the cantilever steps are inset into surrounding wall and are approximately 1200mm wide. 

This design was likely inspired by Andrea Palladio’s stairs in the Convento della Caritá, Venice – which in turn may have influenced Wren’s spiral stairs in the Chapel in the Old Royal Naval college.

Palladio’s Spiral Stairs at Monastery of Santa Maria della Carita, Venice. Credit Gardiner Hallock
Chapel Stairs at Old Royal Naval College Chapel, Greenwich.

The first spiral stairs to be built in Great Britain without any central support; the diameter divided into four; “two parts given to the steps and two to the vacuum” – as described in the notes of Inigo Jones.

The full scan capture of the staircase consists of 19 individual scans taken at regular points around the flights. The glass lantern / roof light allows – overcast in this case – daylight in.

360 Camera View
PolyCam App: Preliminary Scan

Successful registration of the scan set requires common, identifiable points in each that overlap enough to create links and tie them all together. Since there are so many similar elements on different storeys the auto registration process incorrectly places them all as if on a single floor – the wall / stair / handrail scans on different flights all appear the same to the software; though properly aligned in the X-Y axis they are dropped all together in the Z. Manual correction was necessary in this case to pull scans up to the correct elevation and produce the proper model.

The point cloud model allows outer elements to be masked away to reveal just the cylinder space of the stairs and landings. Software camera lens settings can show the structures in orthographic projection or with contrasting field of view settings to generate natural or exaggerated and distorted perspectives.

Sources:

George H Chettle, Survey of London Monograph 14, the Queen’s House, Greenwich (London, 1937)

Pieter van der Merwe  – The Queen’s House Greenwich

Royal Museums Greenwich www.rmg.co.uk

All images by author unless indicated