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View Full Version : all OBJ export options, strip out the UV maps?



eblu
10-23-2014, 09:31 PM
what gives? I remember happily making uv maps and exporting them in my OBJ objects.

today I had some trouble exporting a transformed sequence, and tried to track it down. in LW Layout and Modeler there are a handful of OBJ export options, and today, NONE of them have properly saved an OBJ with it's UV map intact.

did I just get lucky that last time? has it always been this way?
this makes the OBJ export options all worthless.

Sensei
10-23-2014, 10:30 PM
You have to use UV map in some surface (Texture some channel with UV Map). It always was this way, and always will be. OBJ format supports single one UV map. While LW supports unlimited quantity of UV maps. It's the only way to tell exporter which UV map you have in mind to export or not.

CaptainMarlowe
10-24-2014, 11:19 PM
You can have multiple UV maps in .OBJ. I'm using this function all the time when sending an object from LW to substance designer, or Vue, or for selling on TS. For instance, if I send an .lwo with multiple UVs in Vue, only one UV will be read. If i export to .OBJ and load in Vue, all the UV maps will be read.

Sensei
10-24-2014, 11:59 PM
You can have multiple UV maps in .OBJ.

Here is .obj specification
http://en.wikipedia.org/wiki/Wavefront_.obj_file
Please show me where do you have support to multiple uv maps?

Vertex texture data are set by vt command. Parameters are u,v.
Polygon data are set by f command (f-face). Parameters are vertex index, uv index, normal vector index.


I'm using this function all the time when sending an object from LW to substance designer, or Vue, or for selling on TS. For instance, if I send an .lwo with multiple UVs in Vue, only one UV will be read. If i export to .OBJ and load in Vue, all the UV maps will be read.

Please show me example .obj with multiple uvs in that case.. With just one surface.

Here is attached LWO with two uv maps "Texture" and "Texture 1". Each box has separate uv map.
Export it to .obj
Open in text editor, or load in Modeler, and you will see there is just one uv map starting with name of file "2_uv". Second uv map is gone.

125212

CaptainMarlowe
10-25-2014, 02:01 AM
OK, I guess I understand. I usually have on UV per surface on my exported models (and most of the time, it is also a specific layer, although not systematically) with an image assigned to the surface with the UV. This way, it usually works fine.
On the example below (uploaded in OBJ in skecthfab), I had three UV maps, each with a specific texture image, in 4 layers.
1 layer for the wheels (with a specific UV map)
1 layer for the base (with a specific UV map)
1 layer for the main body and 1 for the turret (with a common UV map).

https://sketchfab.com/models/8aa9c1931de342d4bb80f697b5d9d461

Edit : Curiously, when importing it back in LW it separates the 4 UV maps in several surface-based UV map. The UV map for the body becomes divided in sub-usv like "main body_camo" and "main_body_glass" etc.

Sensei
10-26-2014, 12:49 AM
Some apps split layers to separate objects.

bobakabob
10-26-2014, 04:54 PM
I'm on the penultimate LW build so need to update, but have experience obj not exporting well into Maya. Large objects just crash Modeller. Has anyone had this problem?

FBX seems a great solution... Is this the best option for professional pipelines?