Frequently asked questions about LightWorks

by GRAPHISOFT, Katalin Götz and Emőke Csikós · updated: 12.30.2011

Note: ARCHICAD 18 introduced a new rendering engine: CineRender.

LightWorks rendering engine is incorporated into ArchiCAD from version 9. LightWorks rendering engine is developed by LightWork Design

Q: Does LightWorks in ArchiCAD supports radiosity?

A: No, currently Ray-tracing is supported

Q: Does LightWorks in ArchiCAD support multi-threading?

A: Yes, although not all of the rendering modes in LightWorks are multithreaded. Therefore some settings cause the rendering process to use one processor only.

Q: What settings are limiting the multi-thread functionality?

A: There are two settings:

  • If Antialiasing is set to “best”, then the projection will use scanline rendering which is a single-thread rendering mode in LightWorks
  • If Realistic Sun is used, then the rendering will break down to separate threads, but only one of these threads will be active most of the time, while the others will be idle, therefore there will be no performance benefit over a single-processor computer .

Q: When do I need to set Antialising to best?

A: You will probably only need this option when you have very thin (1-pixel) elements (e.g. wires) that run at a steep angle in your composition.

Q: When do I need to turn Realistic Sun on?

A: Realistic Sun has the benefit of most accurate shading, because it uses ray tracing algorithm. The rays of the Realistic Sun will penetrate transparent materials, while the simple Sun will not penetrate such materials, creating a less realistic shadow casting. Since the use of Realistic Sun puts a heavy burden on performance, use it only when you do the final renderings. You can improve rendering speed by setting the Number of Samples value lower.

Q: Can LightWorks take advantage of more than 2 processors?

A: LightWorks will use as many processors as many you have. However, do not expect rendering times to be divided by the number of processors compared to a single processor. Photo rendering has 3 stages: creating 3D model, converting model to LightWorks format, then rendering. Only the 3rd stage is multi-threaded.

Q: Rendering an image fails due to lack of memory. How do I fix that?

A: Read this article: LightWorks memory usage

Q: Is ArchiCAD LWA-Enabled ?

A: This feature is not yet implemented in ArchiCAD.

Q: Where can I learn more about LightWorks rendering in ArchiCAD?

A: Dwight Atkinson’s ‘LightWorks in ArchiCAD book is a highly recommended read if you are interested in learning more about this topic

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Is rendering with LightWorks twice as fast on a dual-core processor?

Creating a rendered image involves separate steps. When you start a “Photorender projection”, first the 3D model of your project is generated in the 3D window, then the model is converted into LightWorks data format, and only the last step is the so-called “rendering”, when the lines of the image are starting to appear on screen. In the latest version of ArchiCAD, most of these steps are multithreaded. Only the last phase is multi-threaded prior to ArchiCAD 12.

I never use LightWorks. Does it make any sense at all to buy a dual-core, quad-core, or more, computer?

Absolutely, because of the tremendous performance gains achieved in ArchiCAD due to multithreading. Even though earlier versions of ArchiCAD will typically use only 50% percent of the CPU resources, you are always running other tasks as well – invisible (or not so invisible) operating systems tasks, or user tasks such as another copy of ArchiCAD, for example. During processor-heavy activities (e.g. 3D model or section generating, publishing, updating layouts) when ArchiCAD’s CPU usage maxes out, your system will still be responsive when you try to use other applications. For example, when you are updating drawings that are linked into another ArchiCAD project, the Background ArchiCAD – which is another copy of ArchiCAD – will not keep you from working on in the open project. Dual-core will benefit everyone. Quad, Oct-core, or higher will benefit users with reasonably complex models as well as those doing a lot of multitasking. Visit archicad-talk and search for discussion threads concerning purchasing new machines.

I am rendering with LightWorks, but it still seems that both processors stop at 50%

There are areas in LightWorks that are not multi-threaded. Depending on the antialiasing level and other settings, it is normal that LightWorks renders with only one thread. See more in the LightWorks article

Can LightWorks use 4 processors?

Yes. Theoretically, LightWorks can use as many processors as you have.




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