Q: I would like export an .obj file (.obj file and associated mtl file) made with the Kenmah pier data (http://www.ilinks.us), but we’ve had some snags with the mtl file. Could you explain please?

A:  A .mtl file is the file that has all the material info for an .obj file (colors + textures (if any)). 

The .obj file, where is needed, is referencing the materials that are written inside the .mtl file.

The .mtl file as a general rule should sit exactly next to the .obj file and in general both should have the same name (though there are some exceptions but not needed to dig deeper)

The .mtl file can reference any kind of image extension (such as the most commonly used, .jpeg, .png)
NaviModel supports the most common image extensions and so a jpeg should definitely work.

 This is a simple example of a material info inside .mtl file:


!Important note: Be aware that the path to the image is not absolute! An absolute path will point to a folder existing in creator’s local computer.
 The general rule is that the image is being located either on the same folder as the .obj and .mtl file (like in this example case)

Or it is inside a folder named textures located on the same folder as the .obj and .mtl file.