BIMNode

The BIMNode class in Geomapi represents the data and metadata of ifc data. The data itself and methods build upon Open3D TriangleMesh and IFCOPENSHELL concepts while the metadata builds upon the RDFlib framework:

The code below shows how to create a BIMNode from various inputs.

First the geomapi and external packages are imported

#IMPORT PACKAGES
from rdflib import Graph
import os
import numpy as np

#IMPORT MODULES
from context import geomapi #context import for documentation only
from geomapi.nodes import BIMNode

Jupyter environment detected. Enabling Open3D WebVisualizer.
[Open3D INFO] WebRTC GUI backend enabled.
[Open3D INFO] WebRTCWindowSystem: HTTP handshake server disabled.

BIMNode Creation

A BIMNode is constructed using the same parameters as the base Node. Please refer to Node Tutorial For more info about Node Creation

BIMNode( subject = None,             # (URIRef, optional) : A subject to use as identifier for the Node.
          graph = None,               # (Graph, optional) : An RDF Graph to parse.
          graphPath = None,           # (Path, optional) : The path of an RDF Graph to parse.
          name = None,                # (str, optional) : A name of the Node.
          path = None,                # (Path, optional) : A filepath to a resource.
          timestamp = None,           # (str, optional) : Timestamp for the node.
          resource = None,            # (optional) : Resource associated with the node.
          cartesianTransform = None,  # (np.ndarray, optional) : The (4x4) transformation matrix.
          orientedBoundingBox = None, # (o3d.geometry.OrientedBoundingBox, optional) : The oriented bounding box of the node.
          convexHull = None,          # (o3d.geometry.TriangleBIM, optional) : The convex hull of the node.
          loadResource = False,       # Load the resource at initialization?
          ifcPath = None,             # (Path, optional) : path to IFC file     
          globalId = None,            # (str, optional) : IFC globalId
          className = None,           # (str, optional) : IFC className e.g. IfcWall, IfcBeam, IfcSlab, etc.
          objectType = None           # (str, optional) : IFC object type e.g.  i.e. Floor:232_FL_Concrete CIP 400mm
        )

Ontology link

The BIMNode has 4 new standard properties that are serialized to the graph:

python name	predicate
`ifcPath`	`ifc:ifcPath`
`globalId`	`ifc:IfcGloballyUniqueId`
`className`	`ifc:className`
`objectType`	`ifc:objectType_IfcObject`

Creation From IFC file

Since IFC files contain a large amount of elements, they cannot be loaded directly into a BIMNode. Use the geomapi.tools.ifc_to_bim_nodes function to load all elements into a list of BIMNodes.

import geomapi.tools as tl

bimnodes = tl.ifc_to_bim_nodes(path = r"../../..\tests\testfiles\ifc\parking.ifc", classes='IfcColumn')
print(len(bimnodes))

BIMNode Resource

When creating a BIMNode with a resource, it can be done either directly with the resource, or with the path to the resource. The resource can be a o3d.geometry.TriangleMesh, trimesh.base.Trimesh or an ifcopenshell.entity_instance. The resource is always converted to a o3d.geometry.TriangleMesh

A resource can be a big piece of data, this is why it is not always wanted to load the whole resource at initialization. This is why the loadResource parameter is default to False

Loading The Resource

node = BIMNode(path=r"../../..\tests\testfiles\ifc\Basic_Wall_168_WA_f2_Soilmix_600mm_956569_06v1k9ENv8DhGMCvKUuLQV.ply", loadResource=False)
print("resource before loading:",node.resource)
node.load_resource() # Use specialized node fo each type of resource.
print("resource after loading:",node.resource)

Resource not loaded, but path is defined, call `load_resource()` to access it.
Resource not loaded, but path is defined, call `load_resource()` to access it.
resource before loading: None
resource after loading: TriangleMesh with 16 points and 28 triangles.

Saving The Resource

A BIM resource can be saved to disk using the save_resource() function. Currently supports: .ply, .obj

node = BIMNode(path=r"../../..\tests\testfiles\ifc\Basic_Wall_168_WA_f2_Soilmix_600mm_956569_06v1k9ENv8DhGMCvKUuLQV.ply", loadResource=True)
node.save_resource(directory=r"../../../tests/testfiles/resources", extension=".ply") # Save the resource to the resourcePath

True

BIMNode Transformation

Since every nod has a cartesian transform, it can be transformed using the node.transform() function.

The transformation also updates the convexHull and orientedBoundingBox.

Furthermore, if the BIMNode has a resource, that resource is also transformed.

node = BIMNode()
print(node.cartesianTransform)
transformation = np.array([[0,0,1,0],[0,1,0,0],[1,0,0,0],[0,0,0,1]])
node.transform(transformation=transformation)
print("applying transformation: (-1)")
print(node.cartesianTransform,"\n")

node = BIMNode()
rotation = np.array([90,0,0]) #eulers in degrees
node.transform(rotation=rotation)
print("applying rotation: (90,0,0)")
print(node.cartesianTransform,"\n")

node = BIMNode()
translation = np.array([1,2,3])
node.transform(translation=translation)
print("applying translation: (1,2,3)")
print(node.cartesianTransform)

[[1. 0. 0. 0.]
 [0. 1. 0. 0.]
 [0. 0. 1. 0.]
 [0. 0. 0. 1.]]
applying transformation: (-1)
[[0. 0. 1. 0.]
 [0. 1. 0. 0.]
 [1. 0. 0. 0.]
 [0. 0. 0. 1.]] 

applying rotation: (90,0,0)
[[ 1.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00]
 [ 0.000000e+00  6.123234e-17 -1.000000e+00  0.000000e+00]
 [ 0.000000e+00  1.000000e+00  6.123234e-17  0.000000e+00]
 [ 0.000000e+00  0.000000e+00  0.000000e+00  1.000000e+00]] 

applying translation: (1,2,3)
[[1. 0. 0. 1.]
 [0. 1. 0. 2.]
 [0. 0. 1. 3.]
 [0. 0. 0. 1.]]

BIMNode Visualisation

When a BIMNode has a resource, the show() function displays the BIM using either open3d or Trimesh, depending on the workspace.

Use the inline = True parameter to display the Mesh using the Trimesh viewer in your jupyter notebook file. Otherwise the function opens a new python window to display the open3d viewer

node = BIMNode(path=r"../../..\tests\testfiles\ifc\Basic_Wall_168_WA_f2_Soilmix_600mm_956569_06v1k9ENv8DhGMCvKUuLQV.ply", loadResource=True)
node.show(inline=True) # The standard node has no resource to display