Thursday, 31 March 2016

Exporting for 3D print

The subject of this blog is one of those topics that rarely gets covered in depth. In practice I am frequently telling customers to move their data to the origin before exporting for 3D print. But why is this? 

Many BIM, CAD and 3D modelling programs have a very large drawing space. An example of why this would be useful is when designing a very large structure like a road or railway. Similarly a large coordinate space allows buildings to be designed at their correct location in relation to a city grid.

When exporting 3D models for applications such as 3D printing a problem can occur causing the exported data to become deformed as shown in the image below. 

Bad STL export of sphere from Rhino when
deliberately modelling far from origin

The problem seems to be that most 3D modelling programs are based on geometric modelling Kernels such as ACIS or Parasolid. These work fine when close to the origin but lose accuracy outside of the kernel's modelling space. 

Confusingly many of the applications functionality is unaffected by modelling outside the kernels modelling space but certain functions either fail completely or result in degraded data.

In MicroStation for example the coordinate system (Working Area) will go well beyond a million km from the origin but the Solids Area is only a 4.2km cube. The 4.2km limit being set by the Parasolid modelling kernel used in MicroStation. When you draw more than 2.1km from the origin the lower resolution may not be immediately apparent but may manifest downstream, such as when you export to STL etc.

This is not a problem restricted to MicroStation. It is a problem with most 3D modelling packages. As a consequence it is always best practice to model near the origin whenever possible. 

Modern Architectural Design Tools Timeline

The following timeline places various architectural design tools by date. The purpose for this record was to create a context in which to view 3D printing as a design tool. From this point of view, today (2016) it is clear that the use of 3D printing in architecture is still very new. Even though early adopters were employing SLS and SLA printing for architectural model making in the 1990s and plaster-based printing from the 2000s these are still few and far between. 

Four buildings have been added to the timeline to act as a reference. These are somewhat arbitrary and do not necessarily represent precedents in use of technology. 

Each of the buildings shown relate in some way to the story of computing in architecture, not least the Lloyds building, the design of which commenced before any of the CAD packages that we know today. The Lloyds building was designed and built in the period that saw the appearance of the first personal computers. This led to a change in the way buildings are used and serviced and consequently changed the form of the buildings themselves. The affect of computing on architecture is undeniable but not always obvious. New design tools change the way architects work but the affect of design tools on the design of the buildings produced is sometimes less easy to identify.

There have been a great many pioneers of architectural design tools. Many tools have been developed and for one reason or other they have been abandoned or superseded.  It is worth making the observation that there is often little inclination to share detailed information on active design projects. Once buildings are complete and considerations of confidentiality have past these details fade from memory as focus switches to new challenges. Therefore much pioneering work is lost to public record. This timeline is admittedly only the bare bones of the story. 

1928 Tintenkuli nibless drawing pen (precursor to Rotring Rapidograph)

1953 Rotring Rapidograph drawing pen

1953 IBM 650 series of computers

1956 First computer keyboard

1957 Jorn Utzon wins international competition to design Sydney Opera House. Ove Arup & Partners engaged as engineers.

Detalle interior ópera Sydney
Sydney Opera House detail
Image by Leithcote / Antony Oliver (Flickr)
via Wikimedia Commons

1959 Letraset founded - manually applied lettering system

1959 Calcomp 565 pen plotter 

1960 DEC release first Mini Computer, the PDP-1, priced between $125,000 and $250,000. This computer was used to play 'Spacewar', the first digital screen game.

Spacewar running on PDP-1
Image Joi Ito via Wikimedia Commons

1962 Douglas Englebart envisions BIM in "Augmenting Human Intellect". He anticipates 
object based design, parametric manipulation and a relational database

1963 Ivan Sutherland writes Sketchpad considered to be the ancestor of modern CAD programs

1963 First Pantone Matching System Printers Edition

1963 First computer mouse, invented by Douglas Englebert

1965 After 8 years work on Sydney Opera House Tim Rice and Tony Cramm write a program from scratch, they run it at night borrowing time on an Australian General Electric computer to calculate positions of pre-cast segments. 

Sydney Opera House construction 1968
Sydney Opera House 1968
Image by PhillipC (Flickr) 
via Wikimedia Commons

1968 Conference 'Computer Graphics in Architecture and Design' Yale University

1969 Appalachian Conference, led by SOM at an IBM research facility. Out of this was formed the SOM, Computer Group

1973 Sydney Opera House opens

1974 Intergraph IGDS, precursor to MicroStation

1975 DRAW2D, SOM Computer Group

1977 DRAW3D, SOM Computer Group

 1977 Really Universal Computer Aided Production System (RUCAPS) sold through GMW Computers Ltd (from GMW Architects)

1978 Richard Rogers begins work on Lloyd's Building

1981 IBM launches first Personal Computer running Microsoft MS DOS 1.0

1982 AutoCAD 1.0

1982 Catia 1.0

1982 Romulus, the first 3D modelling kernel. Later becomes ACIS.

1984 MicroStation 1.0

1984 ArchiCAD 1.0 (named Radar CH for first version only)

1984 First HP LaserJet printer, Apple's LaserWriter followed the following year

1985 MiniCAD 1.0 (later renamed VectorWorks)

1986 Lloyds Building completed

Richard Rogers Partnership, Lloyds Building detail
Image from Oast House Archive via Wikimedia

1987 First commercial SLA 3D printer, SLA-1, made by 3D Systems

1988 STL file format 

1989 First Commercial SLS 3D printer built by DTM (later acquired by 3D Systems)

1989 ACIS 3D modelling kernel

1989 Parasolid 3D modelling kernel

1990 Photoshop 1.0

1992 Magics 1.0 (an STL editor which became the industry standard software for 3D print bureaus.

1993 PDF 1.0

1994 Gehry Technologies founded

1997 First commercial Z Corporation 3D printer, Z402

1997 Foster + Partners begin work on 30 St Mary Axe

1998 Foster + Partners' Specialist Modelling Group formed, 30 St Mary Axe becomes one of their first projects 

1998 Rhinoceros launched

2000 Morphosis buy a ZPrinter from Z Corporation. They are one of the first architectural practices to run a 3D printer in-house.

2000 Revit 1.0

2001 Microstation v8 (file format changes for first time)

2001 Smartgeometry Group formed

2002 Autodesk acquire Revit

2002 AutodDesk whitepaper "Building Information Modelling"

2003 Bentley Systems' Generative Components in Alpha

2003 64-bit processors become available in personal computers

2004 Morphosis begin designing Cooper Union building using 3D printing as part of the design process

2004 Foster + Partners' 30 St Mary Axe completed

Foster + Partners, 30 St Mary Axe
Image by Nevilley via Wikimedia

2005 Launch of Spectrum 510 colour 3D printer by ZCorporation. The increased resolution and build size meant reasonable quality architectural concept models could be printed overnight. 

2008 - ZPrinter 650, replaced for the 510 with slightly larger build 

2008 Great Recession begins

2009 Morphosis's Cooper Union building completed

Morphosis, Cooper Union building
Image by Short Dale via Wikimedia

2012 3D Systems acquires ZCorporation and rebrands the ZPrinter range as ProJet x60


2016 Digital Craft - 3D Printing for Architectural Design, written by Bryan Ratzlaff and published by Lee 3D. The first book to deal with 3D printing for architectural design as its sole subject.  

Find out more about Digital Craft at