Convert OBJ files to FBX files pros and cons

Question

I would like to know what happens when I decide to change my mesh in OBJ to FBX files.

For example, I had make a retopo in topogun, which only supports OBJ and their respective files convention. When I open it in Blender, everything seems to be right, but I use Unity often for exporting animations and for me, it works easier with FBX.

1. What happen with normals projections from the mesh in the conversion from file to file?
2. Is it the same type of mesh (collada, mesh, etc.)?
3. Is it a good idea to convert obj to fbx for animations for use in an engine?
4. I use xnormal for baking normal maps and I always use OBJ for both models in case I have got a HP and LP. I create the maps, go back to Blender and see the results, but when I decided to export the whole model with textures an animation, I change the OBJ to FBX. I do not see visual changes, everything seems to be right, but I would like to know the pros and cons, or whatever to develop my game or startup project.

My target: lowpoly games 2k to 20k, animations in Blender to use in Unity.

Answer 1

you have to understand that .obj files and .fbx files are following different concepts.

The .obj file format is a simple data-format that represents 3D geometry alone. In other words, its a simple text-based file that is primary for storing Meshes.

And a .fbx file format (and collada file as an open source equivalent) can store whole scenes (Camera, Armatures, Meshes, Curves, Empties, Lights, etc).

An .obj file can store:

1. Meshes information (Vertices, Edges, Faces) in multiple objects
2. Normals
3. UVs

4. Object information like Position, Rotation, Scale (in relation to each other!, I've often found that the obj exporter created files which had different dimensions in Blender to Meshes that had the same bounding size after importing to a different engine (Please correct me if I am wrong)

5. Some basic material information in a Separate .mtl File (nothing like complex cycles nodes)

6. Some Programs(Zbrush, XNormal, not Blender) can read and write Vertex colors to the obj file

7. It is possible to create .obj animations and some engines are even capable to read them. But you have to know that blender creates for every frame a new objfiles. So, most of the time, nothing you would like to have in your realtime engine

As mentioned above, a fbx file can store a lot of things. Essential is what your exporter(Blender) and your importer (Game engine) is capable of reading and writing.

I definitely would recommend to use fbx or collada for any kind of exchange. I had significant problems with obj.

to answer your questions:

What happen with normals projections from the mesh in the conversion from file to file?

1. Normals should be the same in every file format

Is it the same type of mesh (collada, mesh, etc.)?

2. Yes, it is the same type of mesh.

Is it a good idea to convert obj to fbx for animations for use in an engine?

3. Definitely

I create the maps, go back to Blender and see the results, but when I decided to export the whole model with textures an animation, I change the OBJ to FBX.

4. What you do in the process of creating your models doesn’t matter. You only want to prevent data loss. Obj is ok for texture generation with XNormal. Fbx is also ok.