the modelindex and occlusion model work well with your models , no problemo.
But when i tried to make my custom TERRAIN_ and BUILDING , the rendering is all wrong and it seems that there is requirement about the scene not explain in the doc like naming convention for BUILDING, NODE , LINK.
As well what is the diff between what you call link and node , they all refer to roads…it s a bit confusing for someone that want to use this fabulous piece of code.
May you tell me how do you nest your scene nodes , or if you could provide us a collada that was use for the city it will help , to discover the requirement to make it work fully from scratch.
we learn alot with all this samples