« The Kinect wall of fa… | Home | GreenSpider goes acad… »

GreenSpider test drive on existing buildings

Little tutorial on vaults modeled in Revit

Scritto da Silicon_Simon.
Giovedì 20 Giugno 2013, 4:34 pm.

In my research, I'm deeply concerned about representing existing buildings in BIM domain. Thence, historical buildings are considerably a further reason for my interest. GreeenSpider was originally imagined as a piece of code able to traslate points as reference in Revit, with particular interest in Rhino+Grasshopper's parametric morphologies. However, dealing with real buildings, translating decimated point clouds from laser scanning or digital photogrammetry appeared to be feasible as well.

This post is intended as a practical example of GreenSpider implementation in real world documentation: in this case I would introduce a working pipeline on vault modeling in Revit from an accurate TLS survey.

The quality of data in a laser scanning survey is unequivocally important; starting our work with GreenSpider from a clean and consistent point cloud is, this way, unavoidable.

Using a Faro Cam2 Focus 3D laser scanner (phase shift technology) a vault pertaining to an historical building was captured (see the first picture in this post). This file is often rich of information and every point can be transslated by GreenSpider in a Revit's reference point. However, too many points make a Revit file pretty unmanageable.

Due to this occurrence, point clouds have to be roughly simplified with a rude decimation algorhitm (see first two pictures in the gallery): consider resulting points as a guide for splines tracing in Revit mass modeling environment, they have to be adaptive, correct but not overdetailed, 15 to 30 points per curve are enough.

Every section has to be saved in a single .XYZ file, so we have here 13 different files since I decided to generate 13 slices from the main point cloud.

In picture three of the gallery below, GreenSpider is invoked from Revit GUI, to translate along the Y axis .XYZ slices one by one. GreenSpider is a prototype so it's still not so robust. This means .XYZ in input and resulting .GSP in output have to be carefully checked to work properly. Files with .XYZ extension have to collect coordinates in text format separed by a space, with NO NORMALS (only coords) and no End-of-File character at the end of the list.  an example of .XYZ files used in this tutorial.

In Autodesk Revit, open the mass modeling environment and import translated .GSP files one by one;  you can find files used in this tutorial, to check your work. Generating a surface from splines is very easy and resulting vault can be saved as a template family.

This is the end of the workflow: your vault can be imported in a Revit project as generic family, the exported in IFC format and reimported as a ceiling, a roof, a wall and so on.

Latest GreenSpider is here! 

Nessun commento