Tuesday, May 16, 2017

EB GUIDE 6.4 – The scene graph widget – PART II

Thomas Engelhardt

In my last post, I introduced the scene graph widget, the challenges it can resolve and nodes that it contains. Moving on with scene graph nodes.

Scene graph nodes scale, rotate, or translate their children. They place cameras, light sources and meshes in the 3D world space of the 3D scene and may be arbitrarily nested. This allows grouping objects or constructing complex transformations. Three kinds of light sources place your scene within its true light: (1) Directional light sources mimic sunlight, (2) Point light sources behave like light bulbs, and (3) Spot light sources shift the lighting focus to a user defined cone of influence.

Mesh widgets store the actual visible scene geometry. They are entirely constructed of triangles and can only be created by importing 3D scenes into EB GUIDE. Once imported, meshes might appear broken or incomplete depending on the viewing angle of the camera. This is because face culling is activated by default for best performance. If you encounter such issues, simply deactivate face culling for the affected mesh.



Culling: For performance, culling is enabled by default which may lead to visual artifacts (left). Disabling triangle face culling alleviates the problem (right).

I’d also recommend exporting only the mesh attributes that you actually need from your 3D modelling tool. For instance, only export texture coordinates if you plan to use textures on your mesh.

Finally, the Material widget brings color to your 3D world. It defines the visual appearance of meshes in the presence of the scene’s light sources. The basic material parameters comprise a set of colors that, for example, control the Material’s Phong lighting model uniformly. Textures provide more variety (see image ‘Textures’). Beyond substituting the material’s colors, textures fulfill a variety of additional functions. The (tangent space) normal map adds fine-grained visible surface structure (for example, roughness). For this it is crucial to export tangents and binormals from your 3D modelling tool. Otherwise activating this feature remains without effect. The opaque texture partially stencils out geometry or renders it semi-transparent. Finally, light maps and reflection textures improve realism. Light maps provide the possibility to incorporate precomputed shadows or ambient occlusion. Reflection textures, as the name implies, simulate environment reflections for highly specular surfaces such as car paint.



Textures: A wide variety of optional textures enables more visual detail and realism for your3D scene within EB GUIDE 6.4


With the introduction of the scene graph widget, you now have an improved workflow for integrating 3D content with your HMI model in EB GUIDE 6.4. View the entire structure of the imported FBX or Collada file and have full control over viewing, lighting and the objects’ parameters.

As always, we are constantly looking for ways to improve the tool. Download the latest version of the tool, try it out and send us your feedback.