# Manifold vs. Non Manifold geometries

Hi, All.

My question about these two concepts lies on that I think I understand the difference but I´d like to have it clarified in plain english as my base discipline is architecture and not advanced geometries or computation (though attempting to do my thesis on informational design).

I think there is a really strong field of study around the possibilities of using non-manifold geometries, and their query, to create parametrically sound designs.

Besides the first, could anyone also explain what are the key capabilities a “non-manifold” modeller should have, and if Rhino could be one?

From my limted knowledge and intuition, I guess this approach, coupled with Grasshopper, could be amazing for the initial phases of architectural design.

This from the Rhino help file:

A polysurface or mesh for which every edge is shared by at most two faces is called a manifold.

Edges of polysurfaces or meshes that have more than two faces joined to a single edge are non-manifold.

Does this help?

– Dale

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@arquitextonica I recently met with some Rhino users in the geotechnical industry. For seismic simulation and analysis, they use non-manifold meshes for modelling the internal lattice structures of 3d volumes that could represent the material properties of different soil types.

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The area where I’ve seen non-manifold geometry used is in analysis of “zones”. In a very simplified case, think of a single mesh that looks like two stacked boxes (non-manifold). This would represent two volumes with a face that divides these volumes. The analysis could consider the volumes as rooms in a house or tanks on a ship.

Thanks @RichardZ and @dale so far was already clear for me.

@fraguada and @stevebaer these are two different approaches.

The one stated by @fraguada is really interesting, but “mass” modelling, I think could be related to the concept of materials and voxels (I think Andy Payne researches in that direction). It´s amazing but not my field.

The other stated by @stevebaer is actually what interests me. I think Robert Aish and others research in this direction.
For me the idea/goal of this type of modelling is alike “sketching” in 3D. You build “space” before “construction”. Lines remain lines instead of becoming instantly walls or floors like what happens in hardcore BIM

The querying of this geometry is what really puzzels me. I’ve tried something in this direction, before actually knowing about the concept of non-manifold topologies and came head-first to the querying problem… in grasshopper it was painstakingly hard to devise a system that could be minimallz user friendly and even the result I achieved didn¡t satisfz me… Perhaps @fsalla has some imput about it.