This announcement is out of date, and some information is deprecated. You can find up-to-date information on the Material Editor in our Help Center: https://help.sketchfab.com/hc/en-us/articles/202512446-Material-Editor
Bump / normal map
Normal mapping and bump mapping are techniques meant to achieve the same goal : deform the surface of an object. So why not use the same slot for both ? When uploading a texture, the material editor detects the color and automatically assigns the right type for you.
Polygons located on a mesh have a front and a back side by default. Therefore, wherever you look at you can see something.
However, in some cases you may want to disable this characteristic by unchecking the material option “Double sided” and display only front faces, making the back side invisible.
You can use this option with transparent objects where back and front faces are drawn in a inpredictable order for example.
While it’s not realistic to draw only the front faces of a transparent object, it gives definitely a nicer result.