Entity to map color in each vertex in a mesh model

Developers
1

Hi everyone,
I want to map color data into IFC for a colored mesh model, like below.
It defines RBG in vertices, with the geometry defined as vertices and indexes.
It’s very common in modelling softwares.

Is there any entities to describe it in IFC data schema, like IfcIndexedColourMap (It is describe color for faces.).
color

I will really appreciate your concerns.
Thank You!

Best regards
Shihang

2

The following example might be helpful:
standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/tessellation-with-individual-colors.htm

3

Hi, the IfcIndexedColourMap is used in this example.
I’m afraid it colors the mesh model with individual faces instead of vertices.
So, maybe this entity could not be used to describe this situation.

image
image1820×96 29.1 KB

Best regards
Shihang

4

Clear, so for example a simple triangle with only 3 vertices where each vertex can have its own color and the colors in the triangle ‘smoothly’ transition. By my knowledge this is not possible in IFC, also not in the recent releases. The closest would be most probably using a texture, however textures are available but not widely supported.

5

Yea, there are some entities to map texture to the mesh model, such as the IfcIndexedTriangleTextureMap.
I’m not very familiar with these things, because it’s uncommon in the existing modelling software.

Do you think it’s possible to exchange the colorful cloud data to picture of each face, and then attach them to the mesh geometry with IfcIndexedTextureMap.
And do you think there are existing open source IFC viewer to read and visualize this kind of IFC model.

Best regards
Shihang

6

For sure I think it is possible to exchange the colorful cloud data to picture of each face, and then attach them to the mesh geometry with IfcIndexedTextureMap.

However I do not think you will find (many) viewers that will support this, of course for open source viewers you will have the possiblity to add such functionality.