dotbim (Schema version 1.1.0)

Introduction

Introducing an open-source and minimalist file format for BIM. Built to be easy to read and write.

Created by BIM developers for BIM developers.

An idiot admires complexity, while a genius appreciates simplicity - Terry Davis

Quick introduction video: https://www.youtube.com/watch?v=RSV-0-UrzhQ

BIM vs IFC comparison

	.bim	.ifc
Is it open?	Yes	Yes
Is it free?	Yes	Yes
Type	Text file	Text file
What it contains	Geometry + data attached	Geometry + data attached in a standardized way
Types of geometries allowed	Triangulated meshes only	A lot of different types: meshes, extrusions, b-reps etc.
Pages of documentation	1	100+

To see much more extended comparison check out Dion's comparison here: paireks#8

Guide for developers

If you're a developer, check out this document: https://github.com/paireks/dotbim/blob/master/DeveloperTips.md

Apps supporting .bim

Name	Purpose	Link	Author
dotbim	C# library	you're looking at it right now ;)
dotbimpy	Python library	https://github.com/paireks/dotbimpy
dotbimGH	Grasshopper plugin	https://github.com/paireks/dotbimGH
dotbim-ifc	Converts to and from IFC and dotbim	https://github.com/Moult/dotbim-ifc	Dion Moult
Online 3d Viewer	3d viewer in your browser, it can also convert to and from other file formats	https://3dviewer.net/	Viktor Kovacs, Agnes Gaschitz
dotbim-blender	Blender addon	https://github.com/paireks/dotbim-blender	Nathan Hild
dotbim-io-dxf	Converts to and from 3d DXF and dotbim	https://github.com/Gorgious56/dotbim_io_dxf	Nathan Hild
dotbim-ts	Typescript library	https://github.com/baid-group/dotbim-ts	Maciej Lutostański
dotbim-archicad	Archicad addon	https://github.com/kovacsv/dotbim-archicad	Viktor Kovacs
os4bim/dotbim	Converts Revit's detailed MEP to schematic 3d model	https://github.com/os4bim/dotbim	Yoann Obry
import_dotbim	SketchUp addon	https://github.com/MattiaBressanelli/import_dotbim	Mattia Bressanelli
dotbim.three.js	Three.js addon	https://github.com/ricaun/dotbim.three.js	Luiz Henrique Cassettari
ICEBridge	Blender plugin to send BIM data to IDA ICE	https://github.com/maxtillberg/ICEBridge	Max Tillberg
three.model.bim	3d modelling in browser	https://github.com/RyugaRyuzaki/three.model.bim	Ryuga Ryuzaki

If you're building any app that will use .bim - let me know, I'll post it here :)

NuGet package

https://www.nuget.org/packages/dotbim/

It may require importing another nuget for Newtonsoft.Json library.

Structure

Documentation

Main information

.bim
License: MIT
JSON structure
x, y, z coordinates should be in meters
Decimal point should be used
JSON objects and properties should start with lowercase and with underscore as a seperator between words, e.g. schema_version

file

File contains 4 properties:

schema_version is the version of schema used in this file as string. Current one is "1.0.0".

mesh

mesh_id is integer >= 0 to reference this mesh later in element.

coordinates

It is a big array of all coordinates of a mesh. It is structured in this way:

[X0, Y0, Z0, X1, Y1, Z1, X2, Y2, Z2, X3, Y3, Z3, ..., XN, YN, ZN]

Let's say our mesh is defined by 3 vertices: (0.0, 0.0, 0.0), (10.0, 0.0, 0.0) and (10.0, 5.0, 0.0), then your vertices_coordinates will look like this:

[0.0, 0.0, 0.0, 10.0, 0.0, 0.0, 10.0, 5.0, 0.0]

Later in faces_ids we refer to these vertices by their order.

indices

It is a big array of ids (integers) that define all faces in a mesh. It is structured in this way:

[Face1_Id1, Face1_Id2, Face1_Id3, Face2_Id1, Face2_Id2, Face3_Id3, Face3_Id1, Face3_Id2, Face3_Id3, ..., FaceN_Id1, FaceN_Id2, FaceN_Id3]

If we'd like to create one-face mesh using vertices_coordinates from an example above, then it will look like this:

[0, 1, 2]

Pyramid example:

  "coordinates": [
    0.0,
    0.0,
    0.0,
    10.0,
    0.0,
    0.0,
    10.0,
    10.0,
    0.0,
    0.0,
    10.0,
    0.0,
    5.0,
    5.0,
    4.0
  ],
  "indices": [
    0,
    1,
    2,
    0,
    2,
    3,
    0,
    1,
    4,
    1,
    2,
    4,
    2,
    3,
    4,
    3,
    0,
    4
  ]

element

guid is a string that can be used for comparison of different elements.

"guid": "76e051c1-1bd7-44fc-8e2e-db2b64055068"

vector

Vector places referenced mesh where it should be placed as an element. It should have 3 properties:

x (value)
y (value)
z (value)

  "vector": {
    "x": 9.9266016462536122,
    "y": 3.3910972817343494,
    "z": 52.239445879618685
  }

rotation

Rotation rotates referenced mesh how it should be rotated as element. It is a quaternion. It should have 4 properties:

qx (value) - first imaginary coefficient of the quaternion
qy (value) - second imaginary coefficient of the quaternion
qz (value) - third imaginary coefficient of the quaternion
qw (value) - real part of the quaternion

  "rotation": {
    "qx": 0.63979295771454925,
    "qy": 0.10626982147910254,
    "qz": -0.12472093047736807,
    "qw": -0.7508770776915008
  }

color and face_colors

From schema_version 1.1.0 if face_colors tag is applied, then we color element using face_colors, if there is no face_colors - we use color tag to color an element.

color should have 3 properties:

r (integer between 0-255) - red
g (integer between 0-255) - green
b (integer between 0-255) - blue
a (integer between 0-255) - alpha

  "color": {
    "r": 255,
    "g": 255,
    "b": 0,
    "a": 255
  }

To color single element with multiple colors add "face_colors" tag inside an element. "face_colors" is a simple list of integers (integers should be between 0-255) organised in that way:

[r1, g1, b1, a1, r2, g2, b2, a2, r3, g3, b3, a3, ... rn, gn, bn, an]

It should match each face of the mesh.

So let's say you have 3 faces inside one mesh, and wanted to color first face (triangle) as red (255,0,0,255), second as skyblue (135,206,235,255), third as white (255,255,255,255). Then you will have:

"face_colors" : [ 255, 0, 0, 255, 135, 206, 235, 255, 255, 255, 255, 255 ]

type

Element type. It is a string that specifies what mesh represents. E.g. "Beam", "Plate".

"type": "Beam"

info

info is just a dictionary with string as key and value.

  "info": {
    "Name": "Teapot",
    "Price": "2.50$"
  }

.bim file format encourages users to link their data by attaching URLs inside properties of file or specific elements. E.g.:

  "info": {
    "Name": "Metal sheet roofing",
    "Catalogue": "https://pruszynski.com.pl/t-20-roof,prod,99,2294.php"
  }

Such functionality allows also to link one model with another as well. If you're interested in this kind of linking, check this separate document about it: https://github.com/paireks/dotbim/blob/master/LinkingData.md

Tell me more

If you'd like to read more details about this project, a bit background + line-by-line explanation, you might find this article on BIM Corner interesting: https://bimcorner.com/a-new-bim-file-format/

Authors

Wojciech Radaczyński
Viktor Kovacs

Advisors

Tom Van Diggelen
Harry Collin
Marios Messios

kovacsv / dotbim