Beginner's questions

Hi folks,

I’m new to the world of modelling and VFX and i found Sketchfab after seeing it recommended on Grant Abbit’s youtube channel.

Seems like a really amazing learning resource (and much more besides, i’m sure!).

A couple of quick questions: when i inspect a model, am i seeing everything that went into creating that model? Or can people decide to hold back certain information? (i would imagine not every artist wants to share their inner workings if they took years to develop a certain technique).

Also, when i inspect certain models, they’re smoother than the wireframe, so there must be some kind of “smoothing” going on inside the Sketchfab engine? Or is that smoothing rendered?

In fact this whole smoothing thing is pretty baffling to me.

For example, if i create an object in Blender and subdivide it 7 times, to get an ultra-smooth shape, my computer will fall weeping to it’s knees.

But if i subdivide a couple of times, then apply smoothing, no problem. How is it possible? The computer must, in some way, be subdividing a lot to create the smoothness? Or is it an optical illusion, kinda like a normal map?

And lastly, if one buys a model on Sketchfab, does one always get everything one needs to exactly re-create that model including materials (presuming you have the right software to import it)?

Thanks!

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Without knowing what sort of information you think they might be holding back, it’s quite hard to answer this. In general terms, you’re seeing the result of the techniques they used to create something, and from that can perhaps infer some the techniques used - although this requires some familiarity with 3D modelling and the types of approaches used.

Is this in relation to a specific model you’re looking at?

You kind of answered your own question part way through - this is all down to Normals. More specifically, in the subdivision smoothing example you talk about, this would be the smoothing of Surface Normals where there are shared Verts.

All points in 3D space (Verts) typically have a Normal. Normal Maps are an evolution of this base concept, but instead of applying to the Verts/Faces of your mesh, you’re doing it at a texture level for more detailed results. Normal Maps are typically made using a much higher polygon model to ‘Bake’ that detail onto a lower polygon target mesh to avoid the CPU breaking performance issues you mentioned.

This is likely what you’re seeing when you see a smoother result than the wireframe implies.

Yes and no. As there is no real universal concept of a material in modelling, it is simply the combination of the various texture maps (Diffuse, Normal, Spec, AO, etc etc.) and how they interact with the lighting etc. of the 3D environment they are being rendered in - and even this description is a gross oversimplification of a complex subject. If you wanted to read more about this you should look into ‘Shaders’

So when you buy a model from Sketchfab you should receive the model and any textures used with it, but depending on file format of the model and the application you are taking it into, you may have to set up the materials yourself. You can read more about buying in the help center.

Probably not the best explanations of the subject at hand, but hopefully that was of some help Dazzer :nerd_face:

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