Create models using MicroStation SmartSolids. SmartSolids offer more editing possibilities than SmartSurfaces and are guaranteed to close a complete volume.
Existing building models do not have to be converted to solids. If the model is working well, looks correct and renders properly, then it can be converted to 3D feature.
Existing building models may be built on a digital terrain model (DTM) that represents the ground. This may result in models that are open on the bottom.
Stitch together the building shapes to create a surface that represents the building.
Select the DTM triangles that define the bottom of the building.
Use Trim Surfaces to modify the bottom shapes to fit the rest of the building. The result will be a surface that represents the building bottom.
Stitch the building surface to the bottom surface together.
