IGES import - Architectural modelling - Texturing Part 3

PREPARING THE IGES FILES

Lets just discuss briefly what we did to "prepare" these files before exporting them to RS3D:

Q: Why not simply export the whole architectural documentation into RS3D ?
A: Because most CAD documentation contains "extraneous" information - in the form of dimensions, text labels, hatching, and redundant linework. If we imported such a file - not only would it be terribly complex - but we would have to create all our "3D" elements from scratch by "tracing" the plans.

Typical CAD documentation - we need to simplify CAD files before exporting.

Rather than heading down that path - we can skip a lot of the tedium of creating the walls and roof etc. by creating simple Polylines in the CAD package before exporting. We can reference in the architectural documentation in, and simply trace the walls with a SINGLE polyline. We need these lines to be closed. When these lines are imported into RS3D, we simply give them a height and our 3D geometry is created !

Most of the modeling can essentially be created in the CAD package - by placing simple blocks where windows are, we can Boolean out these from the walls to create the window holes. Put linework at its correct heights in the CAD package too - the more we do in CAD the less fiddling we have in RS3D.

TIPS:

IGES exporting works from a variety of packages - not exclusive to CAD. Microstation exports IGES natively, AutoCAD does not. 3D packages such as Maya import very well, with object structure maintained. IGES file format is very flexible as it imports NURB geometry as well. Basic formats such as DXF do not.

IGES uses color information to derive object levels, not CAD levels. Hence, structure your files based on color - be aware however that one can only utilize the 8 primary colors. (A dark red color object will simply be put in the Red color level in RS3D)

It is often very useful to import the building in stages rather than one file - this gives you flexibility with level structures, and file import type.

RS3D can import IGES files as Polyhedrons, SDS objects or Nurb curves. This only applies for curves themselves - 3D nurb surfaces will always import as just that. A series of curves however can be imported as one SDS object - from which you can build faces, by snapping to the points, to create complex polygon roofs for example - or bring each curve in as individual NURBs curves. Polyhedrons are the most useful for Architectural applications as they are low in complexity and Boolean very well.

Keep in mind that most 3D architectural models become VERY heavy very quickly. Therefore keeping objects in a readable level structure format is imperative. e.g.. Group walls under a "Walls" level, then drop that level under the "house" level, then put the house level under the "Buildings" level etc.

When importing large CAD scale documents, its preferable to keep the units from the CAD file, as most CAD documentation is 1:1 - i.e.. 1mm = 1mm. (Note - most documentation is in mm [in metric]) this can create dimensionally large files in RS3D. We can scale the drawing files on import - but its best to leave the scale tab at 1. The drawback of this, is files can be off the "design plane", or too large for RS3D altogether. One can check the "Center model" option - but keep in mind that this will not necessarily import further files in the correct location.

* Note: The IGES plugin for Realsoft 3D does not come built in - it is an aftermarket plugin developed by a third party.