Open source software for architects


Author: Chen Nan Yang

When I began my career as an assistant architect 12 years ago, I used AutoCAD R12, 3D Studio, CorelDraw 6.0, and Photoshop 4.0 for architectural drawing and 3-D modeling. Today, many architects still use their later versions, but those bulky packages provide many functions an architect will never use. Luckily, there are several open source alternatives that are well-suited for architects — QCad in place of AutoCAD, Blender instead of 3DMax, Inkscape in place of CorelDraw, and the GIMP as a substitute for Photoshop.

CAD is the weakest link in the open source chain for architecture. AutoCAD provides architects with efficient solutions: you can, for instance, put hundreds of doors, windows, or pillars in your plan within seconds. By contrast, in open source CAD, you have to do most of the works from zero. Current open source CAD applications are still not good at handling a mass of standardizing drawings. But if you do unique designs, or would like to develop a custom CAD solution that fits your need, open source is a good choice.

QCad community edition is a simple open source 2-D CAD application that works well for architectural plans. It is very successful in countries and areas such as Taiwan; some Taiwanese companies have taken it as a standard solution for their architectural plans.

The release of the QCad community edition follows a few months behind the professional edition. For example, the latest version of the community edition is, while the professional edition is at The latter charges $33 for a single user. You can also download the demo version of the professional edition and use it for 100 hours with no function limits, though it shuts down once every 10 minutes.

QCad has strong tools for point, line, arc, circle, ellipse, polyline, NURBS, text, dimensioning, hatches and solid fills, and measuring. It can also use raster images, and has many other edit tools. The command line is under the main window, and you can accurately control your drawing here. In a word, an experienced architect can find all he needs for architectural plans.

On the down side, QCad doesn’t support AutoCAD’s DWG files.

Another open source CAD application is BRL-CAD. It handles 3-D CAD for constructive solid geometry (CSG) modeling. Or you can choose Open CASCADE as your platform if you want to develop your own CAD.

3-D modeling and rendering

For 3-D modeling you can choose Blender or the less powerful Wings 3D.

Blender is a small but powerful 3-D modeling, rendering, and animation application. It can import files in DXF, OBJ, and 3-DS formats. You can also put the left view, front view, and planform of your architectural plans in the background of the software to begin your modeling. You can choose elements such as mesh, curve, surface, or meta to do your 3-D modeling in different ways. A new feature in the latest version, Blender 2.44, called Subsurface Scattering (SSS) can help you to work out a perfect virtual reality for “participating media” such as glaze tile and crystal.

You can download some tutorials on If you’re used to 3-DMax, you may feel frustrated when you use Blender for the first time, but if you keep trying, you’ll find it’s simple when you get used to it.

A good companion to Blender for the architect or interior decorator is YafRay (Yet Another Free Raytracer). The latest version, 0.09, contains global illumination (which can make architectural scenes look realistic), skydome illumination, caustics (to deal with light emitted from a point and reflected or refracted from a curved surface), and depth of field and blurry reflections. With YafRay you can render your 3-D model to look a like a real photo in Blender.

Vector and bitmap drawing programs

After finishing your works in Blender or QCad, you may need to polish your graphics using a vector or bitmap drawing programs. Vector programs include Inkscape, Xara LX, and Skencil. Bitmap alternatives include the GIMP,, CinePaint, Gimpshop, and Krita.

Inkscape is an open source vector graphics editor that supports most of the standard drawing features you can find in CorelDraw or Illustrator. You can even create some simple architectural plans using only Inkscape.

The GIMP may be the most well-known open source drawing program. It has powerful painting tools and more than 100 plugins and scripts. You can use it to perfect your 3-D rendering graphics just the way you did in Photoshop.

Angel and devil

You will gain several advantages if you choose open source software for your architectural drawing:

You’ll save money. You may spend zero on your software, not the $10,000 you had to pay before.

The programs will go like the wind on your old computer, so you can save both time and money.

The programs are simple and easy to use. They don’t have too many showy functions, and their interfaces are so simple that you can get used to them within a few hours.

You can download lots of plugins or scripts from open source communities. You can also add functions you need to the software, either by yourself or by picking someone who can offer the service; that’s the benefit of open source.

If you happen to be using a pirated copy of AutoCAD or 3-DMax, you will never worry about that again. This will be very good for your mental health.

But before you move to open source you should prepare yourself:

You should stop thinking about the commercial software you used before. You may think “it’s crazy” when you try these open source applications for the first time and want to turn back to your old software. Be patient and keep trying. You will soon learn their merits and get used to them.

You should also ask yourself if these can meet your need when you have heavy standardizing works to do. If the answer is no, you’d better not change.


The bottom line is that open source software such as Blender, QCad, Inkscape, and the GIMP can do just about any architectural drawing that commercial software can do, though sometimes they are less efficient and not compatible to your previous work (as in QCad’s lack of support for DWG files).

Chen Nan Yang is a freelance journalist and former IT director in Chinese government. He has a bachelor’s degree of architecture and worked as an assistant architect a decade ago.


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