How can you create photo-realistic renderings with a BIM design software? Texture Maps and BIM Software, how are they used?
How can we produce photo-realistic images when rendering scenes in a BIM project? Is it possible to use an integration facility between architectural BIM design and a high quality rendering of the project? These are the two question that we’ll try to answer in this article.
The main factors that contribute to obtaining photo-realistic images are many but a very strong influence is determined by the material properties used to characterize the objects used in the BIM model. Good results come from the use of 3D materials.
But what are they and how are 3D Materials used? What are the different types of Texture Maps that allow us to get photo-realistic effects in our projects?
The connection between architectural BIM design and high quality rendering
We now know that BIM design tends to a multi-disciplinary approach to design allowing whoever is involved in the design process to prepare the necessary construction documents in great detail.
It’s natural to think whether the typical modelling features of an architectural BIM design software can be in someway integrated with a rendering software to produce images and video.
Edificius by ACCA software, has this capability and is equipped with an advanced dynamic integration tool that seamlessly connects BIM and real time rendering. This surely revolutionizes the traditional way of addressing architectural design.
This kind of technology change everything because we can now truly check our design choices in real time and even assess the different effects on materials during the design process simulating lights, shadows and under different wheather conditions too.
How do we get realistic effects with a BIM software
To get these realistic effects when using Edificius, we can use the 3D materials already available in the program’s catalogue or browse through the online catalogue. This catalogue is continuously enriched with objects and materials created by the community of Edificius users but also by ACCA’s technical staff.
But what happens if we need a specific material for special purposes?
Take a look at a material in the Edificius catalogue editor and see the various properties organized into sections.
Here we can see the Properties tab where we can define:
– material texture
– hatch pattern
The lower section of the editor shows a preview image of our material settings.
Operating at this level, by loading a simple bitmap and a material pattern, doesn’t allow us to define a HD Material. In fact, in the Real Time rendering (RTR) view, we won’t see any realistic 3D effects on our materials.
Switching to the effects tab, we can see these 4 separate boxes where the various texture maps can be loaded determining the characteristics of a HD material.
If these image maps are loaded correctly, they allow us to achieve appealing photo-realistic effects when viewing the architectural model.
We’ll be taking a closer look at this aspect later on in this article.
The third tab, Real Time Rendering, gives us the opportunity to dynamically test how our materials will appear in the Real Time Rendering environment.
Let’s go back to the effects tab.
As said previously, these image maps can be compared to different layers forming a given material, that if overlayed, return the materials physical behaviour in terms of reflectiveness, roughness, etc.
How does Material processing work in a rendering engine?
The rendering engine uses various types of “shaders” to calculate a materials reaction to natural or artifical light with maximum precision.
Materials are processed using a combination of fundamental data “channels”. Edificius uses 5 different channels or maps.
Let’s see what these different image maps (channels) look like and how they are processed by the graphic card’s “shader”.
This map is nothing more than the simple colour bitmap (RGB) of our material and is loaded in the “Texture” section of the Materials and Colours category.
This is basically a black and white image map where the dark areas produce an opaque surface effect whereas the brighter areas tell the shader to make the material reflect. The more brighter coloured areas there are, the more the material will tend to reflect in those areas. This map is loaded in the Specular map section of the properties toolbox.
The Normal mapping is a technique used for tricking the eye into seeing surface details when lighting bumps and dents. So Normal maps provide extra details to a material without having to increase model complexity. A common use of this technique is to greatly enhance a material’s appearance and its 3D details. The observer can therefore see elevations or depressions (holes, cracks, etc.) in the surface with an incredible increase in realism.
used as an alternative to the classic normal map, when the rendering engine processes this black and white image map, the resulting image also shows elevations and depresions but in greater detail as it actually modifies the model geometry because every pixel has an elevation value (similar to a GEOTIFF image, another image format commonly used in cartography). In Edificius, the height map is loaded in the HEIGHT MAP channel.
Alpha Mask is a clipping mask that tells the shader which parts of the material are transparent and which parts are covered by the texture. An example could be a glass panel with an overlayed metallic grid. The main material will appear to be glass whereas the other opaque areas will be covered by a metallic effect.
Bump mapping is a technique in computer graphics to make a rendered surface look more realistic by simulating small displacements of the surface. However, unlike a HEIGHT MAP or DISPLACEMENT MAP, the surface geometry is not modified.