# 🪐 Objaverse-XL Rendering Script

![Blender generated with MidJourney](https://github.com/allenai/objaverse-xl/assets/28768645/69064f78-a752-40d6-bd36-ea7c15ffa1ec)

Scripts for rendering Objaverse-XL with [Blender](https://www.blender.org/). Rendering is the process of taking pictures of the 3D objects. These images can then be used for training AI models.

## 🖥️ Setup

1. Clone the repository and enter the rendering directory:

```bash
git clone https://github.com/allenai/objaverse-xl.git && \
  cd objaverse-xl/scripts/rendering
```

2. Download Blender:

```bash
wget https://download.blender.org/release/Blender3.2/blender-3.2.2-linux-x64.tar.xz && \
  tar -xf blender-3.2.2-linux-x64.tar.xz && \
  rm blender-3.2.2-linux-x64.tar.xz
```

3. If you're on a headless Linux server, install Xorg and start it:

```bash
sudo apt-get install xserver-xorg -y && \
  sudo python3 start_x_server.py start
```

4. Install the Python dependencies. Note that Python >3.8 is required:

```bash
cd ../.. && \
  pip install -r requirements.txt && \
  pip install -e . && \
  cd scripts/rendering
```

## 📸 Example Usage

After setup, we can start to render objects using the `main.py` script:

```bash
python3 main.py
```

After running this, you should see 10 zip files located in `~/.objaverse/github/renders`, which correspond to renders of objects from [our example 3D objects repo](https://github.com/mattdeitke/objaverse-xl-test-files):

```bash
> ls ~/.objaverse/github/renders
0fde27a0-99f0-5029-8e20-be9b8ecabb59.zip  54f7478b-4983-5541-8cf7-1ab2e39a842e.zip  93499b75-3ee0-5069-8f4b-1bab60d2e6d6.zip
21dd4d7b-b203-5d00-b325-0c041f43524e.zip  5babbc61-d4e1-5b5c-9b47-44994bbf958e.zip  ab30e24f-1046-5257-8806-2e346f4efebe.zip
415ca2d5-9d87-568c-a5ff-73048a084229.zip  5f6d2547-3661-54d5-9895-bebc342c753d.zip
44414a2a-e8f0-5a5f-bb58-6be50d8fd034.zip  8a170083-0529-547f-90ec-ebc32eafe594.zip
```

If we unzip one of the zip files:

```bash
> cd ~/.objaverse/github/renders
> unzip 0fde27a0-99f0-5029-8e20-be9b8ecabb59.zip
```

we will see that there is a new `0fde27a0-99f0-5029-8e20-be9b8ecabb59` directory. If we look in that directory, we'll find the following files:

```bash
> ls 0fde27a0-99f0-5029-8e20-be9b8ecabb59
000.npy  001.npy  002.npy  003.npy  004.npy  005.npy  006.npy  007.npy  008.npy  009.npy  010.npy  011.npy  metadata.json
000.png  001.png  002.png  003.png  004.png  005.png  006.png  007.png  008.png  009.png  010.png  011.png
```

Here, we see that there are 12 renders `[000-011].png`. Each render will look something like one of the 4 images shown below, but likely with the camera at a different location as its location is randomized during rendering:

![temp](https://github.com/allenai/objaverse-xl/assets/28768645/69d79e26-4df1-4bd2-854c-7d3c888adae7)

Additionally, there are 12 npy files `[000-011].npy`, which information about the cameras pose for a given render. We can read the npy files using:

```python
import numpy as np
array = np.load("000.npy")
```

where array is now a 3x4 [camera matrix](https://en.wikipedia.org/wiki/Camera_matrix) that looks something like:

```python
array([[6.07966840e-01,  7.93962419e-01,  3.18103019e-08,  2.10451518e-07],
       [4.75670159e-01, -3.64238620e-01,  8.00667346e-01, -5.96046448e-08],
       [6.35699809e-01, -4.86779213e-01, -5.99109232e-01, -1.66008198e+00]])
```

**Note.** USDZ support is experimental. Since Blender does not natively support usdz, we use [this Blender addon](https://github.com/robmcrosby/BlenderUSDZ), but it doesn't work with all types of USDZs. If you have a better solution, PRs are very much welcome 😄!