Description

Batch generate RGB-D format image pairs from *.obj models with textures in command line using Blender python script.

Quickstart

~$ python3 obj2rgbd.py
~$ python3 open3d_test.py

Requirements

• Blender 2.80 (need to test 2.82 - didn't work for some models)
• Python3: numpy, matplotlib, Pillow, OpenEXR, open3d (optional)
• Tested in Kubuntu 16.04

Setup

Blender

• Get Blender 2.80 (need to test 2.82 - didn't work for some models)
• Add Blender's path to your ~/.bashrc:

export PATH="/home/$USER/Downloads/blender-2.80-linux-glibc217-x86_64:$PATH"

Python 3

• numpy, matplotlib, pillow and open3d are trivially installed
• OpenEXR

pip install openexr

When it failed to install this link helped.

Details

obj2rgbd.py

~$ python3 obj2rgbd.py [input_folder [depth_map_resolution]]:

input_folder - folder with subfolders with *.obj files, default value - input

depth_map_resolution - units in the depth 16-bit *.png file, default value - 0.1, which is 10cm allowing for 0-6553.5 m range

Value	Depth resolution	Depth range
1	1 m	0-65535 m
0.1	10 cm	0-6553.5 m
0.01	1 cm	0-655.35 m
0.001	1 mm	0-65.535 m

What it does:

1. Makes a list of all *.obj models found in a given input folder's subfolders
2. Runs Blender feeding it with the blender_generate_image_and_depth.py and the list
3. Blender script saves results into output/ (auto created). A single result is a rendered image of a model and the depth buffer saved into 32-bit float *.exr format
4. After Blender is done for all models obj2rgbd.py then generates 16-bit *.png depth images with a given resolution from *.exr files. Results are also in the output/

Example:

1. 10cm depth resolution

~$ python3 obj2rgbd.py input 0.1

open3d_test.py

~$ python3 open3d_test.py [path-to-image-file [path-to-depth-file]]:

path-to-image-file - jpeg, defaults to output/example-test_cube-image.jpeg

path-to-depth-file - 16-bit png, defaults to output/example-test_cube-depth-10cm.png

What is does:

1. Opens RGB-D pair using Open3D python library. First it displays side-to-side, upon closing the first plot - it display a 3D view.
2. Hardcoded parameters inside the script: w=2592, h=1902, fx=fy=2045, cx=1296, cy=951

Example:

~$ python3 open3d_test.py output/example-test_cube-image.jpeg output/example-test_cube-depth-10cm.png

blender_generate_image_and_depth.py

Can be run standalone:

~$ blender -b -P blender_generate_image_and_depth.py -- path1/model1.obj,path2/model2.obj

Notes

• Can have multiple models in the same subfolder
• Model names need to be unique as the output files are dumped in a single output/ folder
• *.obj filename must match with the name inside it. See example model in input/
• obj2rgbd.py running blender -b -P blender_generate_image_and_depth.py -- filelist - Blender runs blender_generate_image_and_depth.py using its bundled python (Python 3.7 in Blender 2.80). Could have a single script for everything but it's too much effort to install openexr to that bundled python.

More models

https://community.elphel.com/3d+map

https://community.elphel.com/3d+biquad

Loading everything can take some time. Once loaded there's a download button in the top-right menu.