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

Website: https://www.dotbim.net

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: https://github.com/paireks/dotbim/issues/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 (alphabetical order)

Export and/or Import of .bim files

Name	Purpose	Link	Author
FacadeOption	Facade modelling	https://app.facadeoption.com	FacadeOption
kolega.space	Generative conceptual design	https://www.kolega.space/	Designbotic
Spacio	Lets you design, analyse, and bring to life properly structured building proposals – all within the same day.	https://spacio.ai/	Spacio
three.model.bim	3d modelling in browser	https://github.com/RyugaRyuzaki/three.model.bim	Ryuga Ryuzaki
T-Rex	Reinforcement in Grasshopper	https://www.food4rhino.com/en/app/t-rex	Wojciech Radaczyński

Viewers that support .bim files

Name	Purpose	Link	Author
dotbim.three.js Viewer	Viewer from dotbim.three.js	Click	Luiz Henrique Cassettari
Online 3d Viewer	3d viewer in browser	https://3dviewer.net/	Viktor Kovacs, Agnes Gaschitz
STEP Viewer	3d viewer in browser	Click	GitHubDragonFly

Connectors - plugins that allow to export and/or import of .bim files to other software

Name	Link	Author
dotbim-archicad	Click	Viktor Kovacs
dotbim-blender	Click	Nathan Hild
DotBimConvert/RevitExporter	Click	Ryuga Ryuzaki
dotbimGH	Click	Wojciech Radaczyński
dotbimRH	Click	Seghier Mohamed Abdelaziz
dotbim.three.js	Click	Luiz Henrique Cassettari
import_dotbim	Click	Mattia Bressanelli

Libraries for developers

Name	Purpose	Link	Author
dotbim	C# library	you're looking at it right now ;)	Wojciech Radaczyński
dotbimpy	Python library	https://github.com/paireks/dotbimpy	Wojciech Radaczyński
dotbim-ts	Typescript library	https://github.com/baid-group/dotbim-ts	Maciej Lutostański

Converters - programs that allow to convert to/from .bim files

Name	Purpose	Link	Author
DotBimConvert/IFC	Convertes to IFC	https://github.com/RyugaRyuzaki/DotBimConvert/tree/main/Ifc	Ryuga Ryuzaki
dotbim-ifc	Converts to and from IFC and dotbim	https://github.com/Moult/dotbim-ifc	Dion Moult
dotbim-io-dxf	Converts to and from 3d DXF and dotbim	https://github.com/Gorgious56/dotbim_io_dxf	Nathan Hild
mesh2mesh	Mac application with ability to convert from .dae, .obj, .ply, .scn, .stl, .usd, .usda, .usdz	https://apps.apple.com/us/app/mesh2mesh/id1672770477	fluthaus
Online 3d Viewer	3d viewer with ability of conversion from .obj, .3ds, .stl, .ply, .gltf, .glb, .off, .3dm, .fbx, .dae, .wrl, .3mf, .amf, .ifc, .brep, .step, .iges, .fcstd.	https://3dviewer.net/	Viktor Kovacs, Agnes Gaschitz

Other projects related to .bim

Name	Purpose	Link	Author
DotBimConvert/Compress	Compress and decompress .bim files	Click	Ryuga Ryuzaki
ICEBridge	Blender plugin to send BIM data to IDA ICE	Click	Max Tillberg
os4bim/dotbim	Converts Revit's detailed MEP to schematic 3d model	Click	Yoann Obry

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.

mesh

mesh_id is integer >= 0 to reference this mesh later in the 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:

1. x (value)
2. y (value)
3. 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:

1. qx (value) - first imaginary coefficient of the quaternion
2. qy (value) - second imaginary coefficient of the quaternion
3. qz (value) - third imaginary coefficient of the quaternion
4. 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:

1. r (integer between 0-255) - red
2. g (integer between 0-255) - green
3. b (integer between 0-255) - blue
4. 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