The materials that you find in the Autodesk range of software products have a materials browser that is similar across the board. It looks something like this.
Besides the user interface colours it is exactly the same. The top image is AutoCAD and the below image is Inventor. The dialog box has the same layout where the local images saved inside the CAD model are represented in the top panel. The left side panel has a list of the material library and then the right window represents the material and has an image of the material.
This layout is similar in Navisworks as well as Revit.
When creating materials there is a certain real world measurement that is used so that when mapped onto your CAD model or element it looks like it is real but what happens when you have created a model or it has been acquired from another party and the scaling is totally out?
This is when the material needs to be edited. When editing materials it is always best practise to make a duplicate of the existing material and then edit. The reason for this is that you cannot undo changes when a material is edited.
To edit the material double click on the material in the material editor.
The below image is what the texture editor looks like.
As you can see you are able to change the size (depicted in mm) for the scale both width and height. The chain next to it links the 2 so if there was a specific ratio it scales accordingly. if you un-tick the chain then you can scale it independently.
Once the changes are made you can go back to your model and see if you have to do any more changes to depict it in a more realistic fashion.