Color / material export details in 3MF

[hartdegenlu89421]

Hi, new here so I hope this question is allowed (here) etc. etc.
I noticed that when I add appearances to bodies in Fusion and export them as a 3mf, they are written as "m:colorgroup" tags to the xml representation within the file. Each of these color groups always contains 2+ colors, where one is usually #A0A0A0FF and the other one the sRGB equivalent of the chosen appearance(s). Are there any sources explaining why it is done like this and whether it is always like this? What is the second color for if it is always (afaik) the same? 

[Drewpan]

Hi,

If you are reading XML files then you are really getting under the hood about how

fusion works. While I am not certain, it appears that there are two versions because

an Appearance is different from a Material. Fusion defaults to all Components being

modeled as Steel and I would suggest that maybe the #A0A0A0FF is related to that.

The sRGB would be, as you suggest, the equivalent colour.

What happens if you change the material to something other than Steel? If you chose

ABS plastic with the same appearance as you wanted does that change what happens?

As to why this is done this way and where would you find documentation or an explanation,

I would suggest that it probably has something to do with the 3mf Standard and the

answer is buried within that documentation. Fusion would have been programmed to

be compatible with the Standard.

Only the Devs would really know the answer to this question.

Cheers

Andrew

[hartdegenlu89421]

Thanks for the answer & the tip, I will certainly look into it! 
I'd already scoured the 3mf specification, but apart from the general way of saving materials in colorgroups it doesn't say anything particularly helpful about the topic. That's why I think it's rather Fusion specific. It would totally make sense though, if the second color refers to the physical material applied / the default material.