# Geometry Modeling

Hi all,

I opened this topic to discuss about geometry and geometry related topics

Topics like Solid and Surface modeling, and also hybrid modeling which supports solid and surface paradigms together (common on the PLM industry)

File formats to choose the best schema that supports geometries well, like JT = STEP AP 242 (ISO 10303-242), like USD, like IFC, ...

And modeling methods, Top-Down and Bottom-UP

## Comments

Good subject

*Geometry is KING*

Naming parts is less impromant than the structure provided.

Conversions KILL stucture

Therefore the whole oncept of BIM is still veru weak.

@magicalcloud_75 Hi Hans, happy see you hear.

Yes, "Geometry is KING" and hope soon we all start a discussion about all paradigms and each one is good for which use case or use cases?

@Moult Dion, I think there's a need to write an article about geometric modeling which would be accurate as well as coherent

I think these articles are good to start:

I add the question I asked here too:

Is there any advanced mathematical geometric modeling paradigm like NURBS that is suitable for many environments, manifolds and many purposes like modeling, visualization, emulation, simulation, analysis, etc and transformable to other paradigms and vise versa?

Known workflow: Brep (NURBS) --> Mesh ((sometimes optimized) triangular or quads)

Mesh --> Brep is an opened issue

In what context do you see useful to go from Mesh to Geometry?

Good question, I think there are some technologies/methodologies that just are suitable to generate mesh and just produce mesh, like AI/ML/DL related areas like Laser Scanning, like Photogrammetry, etc

I think I added one more just here "and just produce mesh" the correct

@Moult Please open edit, you said you will open it, but it seems that you didn't, also, sometimes it has issues in saving and loading content

I think I added one more just here "and just produce mesh" the correct is: and produce mesh

Also, for instance Blender, which is mainly Polygonal Modeling tool, so for Blender Mesh to Brep is an opened issue if someone thinks about generate for instance stair modeled on Blender directly into Brep (NURBS) or CSG (https://community.osarch.org/discussion/13/building-a-custom-designed-stair-with-blender)

I know about implicit modeling ;)

Don't worry man, understood 😊

For point cloud / laser scanning it makes sense.

For Blender example if you want to end up in having a geometry I don't see why use polygonal modelling in the first place.

Just some thoughts

It's hard for me to understand this:

"For Blender example if you want to end up in having a geometry I don't see why use polygonal modelling in the first place."However, I think there're some solutions/techniques to end up geometry/topology obstacles

I'm working to gather all geometric modeling paradigms and categorize them based on their use cases and purposes, etc to finally come with two vitally important news that proves the way I follow on MaterialPass, ProductPass, and FacilityPass projects, and also "decoupling geometry and semantics" 😀

It is also hard for me to understand what I meant :D :D

Let's forget about it, probably did not make sense

@ReD_CoDE I saw this repo today and I thought of this thread. Not sure it is related but it looks like

https://github.com/pmneila/PyMCubes

Thank you @Jesusbill, it's valuable, I know that isosurfaces are really important, especially in simulations

Implicit Modeling

@yorik @Moult 2016, FreeCAD froum: https://forum.freecadweb.org/viewtopic.php?f=10&t=15885

Hyperfun (SIGGRAPH 1999), (http://hyperfun.org)

Kokopelli (2012), (https://github.com/mkeeter/kokopelli)

ImplicitCAD (2012), (http://www.implicitcad.org)

Antimony (2013), (https://github.com/mkeeter/antimony)

Animation Nodes (2014), (https://animation-nodes.com)

Ao (2016), (https://github.com/mkeeter/ao-guile-repl)

libfive + Studio (2018), (http://libfive.com)

mods (https://github.com/fabfoundation/mods)

Antimony and mods have some similarities with what I follow in IfcXtreme

Geometric Modeling

Geometry Representation

https://graphscad.blogspot.com/ Nodal editor for OpensCAD

https://openjscad.org/ https://github.com/xibyte/jsketcher

Thank you @bitacovir, I'm researching about Function Representation (F-Rep) these days and also Hybrid Representation (H-Rep) (Volumetric geometries/materials/media/data)

So, I confused, there're a lot of things I should consider :smile:

IGA, based on Splines, NURBS, SubD, ...