Verts in blender and viewer do not match

[Tattooshop]

Hey! Why Verts in blender and in viewer when uploading do not match ( greater )?

[ChinRey]

In Second Life - and all other virtual realities/games afaik - each vertice can only be assigned to one material, have only one set of UV coordinates and only have one normal so it's often neccessary for the uploader to split some of the vertices:

 

[Kyrah Abattoir]

Yeah it is called "edge splitting"

Edges get split for various reasons:

• Material change.
• UV seam.
• Hard edge normals