Blender ошибка при импорте obj

You stumbled upon a curious problem with filename handling in the .obj format, that isn’t well defined in the specification. I will discuss this with the Blender devs, perhaps the importer needs small adjustments to parse the file correctly under these specific circumstances. Since it worked in 2.79b it can be considered a regression.

TL;DR The handling for filenames with blanks isn’t well defined in the .obj format specification and Blender expected a different format than what was provided in your file.

The Problem

The .obj is a text format for storing 3D models. The format contains various attributes that describe the geometry of the model. Typically the .obj is accompanied by a .mtl which describes the material and textures applied to the model. In order to keep track which files belong together, the .obj may contain a mtllib attribute followed by the filename of the .mtl.

Usually the beginning of an .obj would look something like this:

# Blender v2.80 (sub 74) OBJ File: ''
# www.blender.org
mtllib test.mtl
o Cube
v 1.000000 1.000000 -1.000000
v 1.000000 -1.000000 -1.000000

In case of your file it is:

# 
mtllib "tree stump1 original model.mtl"
usemtl tree_stump1_original_model
v 4.136163 -1.200306 -10.798826 0.113725 0.152941 0.141176
v 4.140683 -1.205297 -10.794383 0.117647 0.156863 0.145098

Notice that the filename contains quotations marks. This is causing the problem. The software you used to export this model quoted the filename to avoid confusion on how to interpret the filename. While this is common practice in other file formats the specification for .obj doesn’t mention quoting filenames and says specifically:

Blank space and blank lines can be freely added to the file to aid in formatting and readability.

Which can be interpreted as blanks in filenames can be stored as is, which is precisely what Blender does. Unfortunately Blender’s importer doesn’t expect the quotation marks in the filename therefore misinterpreting the correct filepath. This results in the aforementioned error in your question.

The Fix

Open the .obj file in a text editor of your choice an remove the quotes and save. It should look like this:

# 
mtllib tree stump1 original model.mtl
usemtl tree_stump1_original_model
v 4.136163 -1.200306 -10.798826 0.113725 0.152941 0.141176

The file can now be imported by Blender.

You stumbled upon a curious problem with filename handling in the .obj format, that isn’t well defined in the specification. I will discuss this with the Blender devs, perhaps the importer needs small adjustments to parse the file correctly under these specific circumstances. Since it worked in 2.79b it can be considered a regression.

TL;DR The handling for filenames with blanks isn’t well defined in the .obj format specification and Blender expected a different format than what was provided in your file.

The Problem

The .obj is a text format for storing 3D models. The format contains various attributes that describe the geometry of the model. Typically the .obj is accompanied by a .mtl which describes the material and textures applied to the model. In order to keep track which files belong together, the .obj may contain a mtllib attribute followed by the filename of the .mtl.

Usually the beginning of an .obj would look something like this:

# Blender v2.80 (sub 74) OBJ File: ''
# www.blender.org
mtllib test.mtl
o Cube
v 1.000000 1.000000 -1.000000
v 1.000000 -1.000000 -1.000000

In case of your file it is:

# 
mtllib "tree stump1 original model.mtl"
usemtl tree_stump1_original_model
v 4.136163 -1.200306 -10.798826 0.113725 0.152941 0.141176
v 4.140683 -1.205297 -10.794383 0.117647 0.156863 0.145098

Notice that the filename contains quotations marks. This is causing the problem. The software you used to export this model quoted the filename to avoid confusion on how to interpret the filename. While this is common practice in other file formats the specification for .obj doesn’t mention quoting filenames and says specifically:

Blank space and blank lines can be freely added to the file to aid in formatting and readability.

Which can be interpreted as blanks in filenames can be stored as is, which is precisely what Blender does. Unfortunately Blender’s importer doesn’t expect the quotation marks in the filename therefore misinterpreting the correct filepath. This results in the aforementioned error in your question.

The Fix

Open the .obj file in a text editor of your choice an remove the quotes and save. It should look like this:

# 
mtllib tree stump1 original model.mtl
usemtl tree_stump1_original_model
v 4.136163 -1.200306 -10.798826 0.113725 0.152941 0.141176

The file can now be imported by Blender.

1. Check the obj file

In your case the obj is not exported correctly. Obj is a human readable file format it is easy to find the issue. You can check this by open up the file in a text editor of your choice (sublime, gedit…).

To check referenced materials go to these lines:

• mtllib [external .mtl file name]
• usemtl [material name]

In your case mtllib line is correct, but usemtl is missing.

# OBJ FILE
...
f 3103/18700/18700 3081/18701/18700 3119/18702/18700
f 279/18703/18703 3118/18704/18703 274/18705/18703
f 265/18706/18706 3101/18707/18706 278/18708/18706

# usemtl material name (reference to the .mtl file)
usemtl MyMaterialName

You can find the material name in the mtl file in this line: newmtl [material name]

# MTL FILE
newmtl MyMaterialName
Ka 1.000 1.000 1.000     # white
Kd 1.000 1.000 1.000     # white
Ks 0.000 0.000 0.000     # black (off)
map_Ka myMap.jpg         # ambient texture map
...

As last step check if the paths to the textures are correct:

map_Ka my-texture.jpg                           # points to texture in obj folder
map_Ka /home/user/images/my-texture.jpg         # absolute path on unix
map_Ka C:\Users\user\images\my-texture.jpg  # absolute path on windows

Make sure that the filenames of your textures are correct and there are no white spaces in the paths itself. Instead of pointing to the ‘absolute path’, you can also try Blenders Find Missing Files operator. For further information about all the possibilities of obj’s read this wikipedia article.

2. Apply the material

If the material is not applied to the imported object you can select it here:

3. Enable textures in the viewport

• If your textures are pink, see: Why are all the textures in my file pink?
• To display the texture in the viewport see: How to show textures in the 3D View editor?

Comment Actions

(  0.0001 sec |   0.0001 sec) Importing OBJ '/home/philippo/Downloads/Blender Bugtracker/T60387/OBJ.obj'...
  (  0.0005 sec |   0.0000 sec) Parsing OBJ file...
   (  3.5129 sec |   3.5121 sec) Done, loading materials and images...
      3.5140 sec |   3.5132 sec) Done, building geometries (verts:254941 faces:274719 materials: 1 smoothgroups:0) ...
Error: Array length mismatch (expected 11097, got 11094)

Traceback (most recent call last):
  File "/bin/2.80/scripts/addons/io_scene_obj/__init__.py", line 145, in execute
    return import_obj.load(context, **keywords)
  File "/bin/2.80/scripts/addons/io_scene_obj/import_obj.py", line 1201, in load
    dataname,
  File "/bin/2.80/scripts/addons/io_scene_obj/import_obj.py", line 642, in create_mesh
    me.vertices.foreach_set("co", unpack_list(verts_loc))
RuntimeError: internal error setting the array

Вернуться в Общие вопросы

Кто сейчас на форуме

Сейчас этот раздел просматривают: 1 гость