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Instant Neural Graphics Primitives

<img src="docs/assets_readme/fox.gif" height="342"/> <img src="docs/assets_readme/robot5.gif" height="342"/>

Ever wanted to train a NeRF model of a fox in under 5 seconds? Or fly around a scene captured from photos of a factory robot? Of course you have!

Here you will find an implementation of four neural graphics primitives, being neural radiance fields (NeRF), signed distance functions (SDFs), neural images, and neural volumes. In each case, we train and render a MLP with multiresolution hash input encoding using the tiny-cuda-nn framework.

Instant Neural Graphics Primitives with a Multiresolution Hash Encoding
Thomas Müller, Alex Evans, Christoph Schied, Alexander Keller
ACM Transactions on Graphics (SIGGRAPH), July 2022
Project page / Paper / Video / Presentation / Real-Time Live / BibTeX

For business inquiries, please submit the NVIDIA research licensing form.

Installation

If you have Windows, download one of the following releases corresponding to your graphics card and extract it. Then, start instant-ngp.exe.

Keep reading for a guided tour of the application or, if you are interested in creating your own NeRF, watch the video tutorial or read the written instructions.

If you use Linux, or want the developer Python bindings, or if your GPU is not listed above (e.g. Hopper, Volta, or Maxwell generations), you need to build instant-ngp yourself.

Usage

<img src="docs/assets_readme/testbed.png" width="100%"/>

instant-ngp comes with an interactive GUI that includes many features:

NeRF fox

Simply start instant-ngp and drag the data/nerf/fox folder into the window. Or, alternatively, use the command line:

instant-ngp$ ./instant-ngp data/nerf/fox
<img src="docs/assets_readme/fox.png"/>

You can use any NeRF-compatible dataset, e.g. from original NeRF, the SILVR dataset, or the DroneDeploy dataset. To create your own NeRF, watch the video tutorial or read the written instructions.

SDF armadillo

Drag data/sdf/armadillo.obj into the window or use the command:

instant-ngp$ ./instant-ngp data/sdf/armadillo.obj
<img src="docs/assets_readme/armadillo.png"/>

Image of Einstein

Drag data/image/albert.exr into the window or use the command:

instant-ngp$ ./instant-ngp data/image/albert.exr
<img src="docs/assets_readme/albert.png"/>

To reproduce the gigapixel results, download, for example, the Tokyo image and convert it to .bin using the scripts/convert_image.py script. This custom format improves compatibility and loading speed when resolution is high. Now you can run:

instant-ngp$ ./instant-ngp data/image/tokyo.bin

Volume renderer

Download the nanovdb volume for the Disney cloud, which is derived from here (CC BY-SA 3.0). Then drag wdas_cloud_quarter.nvdb into the window or use the command:

instant-ngp$ ./instant-ngp wdas_cloud_quarter.nvdb
<img src="docs/assets_readme/cloud.png"/>

Keyboard shortcuts and recommended controls

Here are the main keyboard controls for the instant-ngp application.

KeyMeaning
WASDForward / pan left / backward / pan right.
Spacebar / CMove up / down.
= or + / - or _Increase / decrease camera velocity (first person mode) or zoom in / out (third person mode).
E / Shift+EIncrease / decrease exposure.
TabToggle menu visibility.
TToggle training. After around two minutes training tends to settle down, so can be toggled off.
{ }Go to the first/last training image camera view.
[ ]Go to the previous/next training image camera view.
RReload network from file.
Shift+RReset camera.
OToggle visualization or accumulated error map.
GToggle visualization of the ground truth.
MToggle multi-view visualization of layers of the neural model. See the paper's video for a little more explanation.
, / .Shows the previous / next visualized layer; hit M to escape.
1-8Switches among various render modes, with 2 being the standard one. You can see the list of render mode names in the control interface.

There are many controls in the instant-ngp GUI. First, note that this GUI can be moved and resized, as can the "Camera path" GUI (which first must be expanded to be used).

Recommended user controls in instant-ngp are:

The "Camera path" GUI lets you create a camera path for rendering a video. The button "Add from cam" inserts keyframes from the current perspective. Then, you can render a video .mp4 of your camera path or export the keyframes to a .json file. There is a bit more information about the GUI in this post and in this video guide to creating your own video.

VR controls

To view the neural graphics primitive in VR, first start your VR runtime. This will most likely be either

Then, press the Connect to VR/AR headset button in the instant-ngp GUI and put on your headset. Before entering VR, we strongly recommend that you first finish training (press "Stop training") or load a pre-trained snapshot for maximum performance.

In VR, you have the following controls.

ControlMeaning
Left stick / trackpadMove
Right stick / trackpadTurn camera
Press stick / trackpadErase NeRF around the hand
Grab (one-handed)Drag neural graphics primitive
Grab (two-handed)Rotate and zoom (like pinch-to-zoom on a smartphone)

Building instant-ngp (Windows & Linux)

Requirements

If you are using Debian based Linux distribution, install the following packages

sudo apt-get install build-essential git python3-dev python3-pip libopenexr-dev libxi-dev \
                     libglfw3-dev libglew-dev libomp-dev libxinerama-dev libxcursor-dev

Alternatively, if you are using Arch or Arch derivatives, install the following packages

sudo pacman -S cuda base-devel cmake openexr libxi glfw openmp libxinerama libxcursor

We also recommend installing CUDA and OptiX in /usr/local/ and adding the CUDA installation to your PATH.

For example, if you have CUDA 11.4, add the following to your ~/.bashrc

export PATH="/usr/local/cuda-11.4/bin:$PATH"
export LD_LIBRARY_PATH="/usr/local/cuda-11.4/lib64:$LD_LIBRARY_PATH"

Compilation

Begin by cloning this repository and all its submodules using the following command:

$ git clone --recursive https://github.com/nvlabs/instant-ngp
$ cd instant-ngp

Then, use CMake to build the project: (on Windows, this must be in a developer command prompt)

instant-ngp$ cmake . -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo
instant-ngp$ cmake --build build --config RelWithDebInfo -j

If compilation fails inexplicably or takes longer than an hour, you might be running out of memory. Try running the above command without -j in that case. If this does not help, please consult this list of possible fixes before opening an issue.

If the build succeeds, you can now run the code via the ./instant-ngp executable or the scripts/run.py script described below.

If automatic GPU architecture detection fails, (as can happen if you have multiple GPUs installed), set the TCNN_CUDA_ARCHITECTURES environment variable for the GPU you would like to use. The following table lists the values for common GPUs. If your GPU is not listed, consult this exhaustive list.

H10040X030X0A10020X0TITAN V / V10010X0 / TITAN Xp9X0K80
908986807570615237

Python bindings

After you have built instant-ngp, you can use its Python bindings to conduct controlled experiments in an automated fashion. All features from the interactive GUI (and more!) have Python bindings that can be easily instrumented. For an example of how the ./instant-ngp application can be implemented and extended from within Python, see ./scripts/run.py, which supports a superset of the command line arguments that ./instant-ngp does.

If you would rather build new models from the hash encoding and fast neural networks, consider tiny-cuda-nn's PyTorch extension.

Happy hacking!

Additional resources

Frequently asked questions (FAQ)

Q: The NeRF reconstruction of my custom dataset looks bad; what can I do?

A: There could be multiple issues:

Q: How can I save the trained model and load it again later?

A: Two options:

  1. Use the GUI's "Snapshot" section.
  2. Use the Python bindings load_snapshot / save_snapshot (see scripts/run.py for example usage).

Q: Can this codebase use multiple GPUs at the same time?

A: Only for VR rendering, in which case one GPU is used per eye. Otherwise, no. To select a specific GPU to run on, use the CUDA_VISIBLE_DEVICES environment variable. To optimize the compilation for that specific GPU use the TCNN_CUDA_ARCHITECTURES environment variable.

Q: How can I run instant-ngp in headless mode?

A: Use ./instant-ngp --no-gui or python scripts/run.py. You can also compile without GUI via cmake -DNGP_BUILD_WITH_GUI=off ...

Q: Does this codebase run on Google Colab?

A: Yes. See this example inspired on the notebook created by user @myagues. Caveat: this codebase requires large amounts of GPU RAM and might not fit on your assigned GPU. It will also run slower on older GPUs.

Q: Is there a Docker container?

A: Yes. We bundle a Visual Studio Code development container, the .devcontainer/Dockerfile of which you can also use stand-alone.

If you want to run the container without using VSCode:

docker-compose -f .devcontainer/docker-compose.yml build instant-ngp
xhost local:root
docker-compose -f .devcontainer/docker-compose.yml run instant-ngp /bin/bash

Then run the build commands above as normal.

Q: How can I edit and train the underlying hash encoding or neural network on a new task?

A: Use tiny-cuda-nn's PyTorch extension.

Q: What is the coordinate system convention?

A: See this helpful diagram by user @jc211.

Q: Why are background colors randomized during NeRF training?

A: Transparency in the training data indicates a desire for transparency in the learned model. Using a solid background color, the model can minimize its loss by simply predicting that background color, rather than transparency (zero density). By randomizing the background colors, the model is forced to learn zero density to let the randomized colors "shine through".

Q: How to mask away NeRF training pixels (e.g. for dynamic object removal)?

A: For any training image xyz.* with dynamic objects, you can provide a dynamic_mask_xyz.png in the same folder. This file must be in PNG format, where non-zero pixel values indicate masked-away regions.

Troubleshooting compile errors

Before investigating further, make sure all submodules are up-to-date and try compiling again.

instant-ngp$ git submodule sync --recursive
instant-ngp$ git submodule update --init --recursive

If instant-ngp still fails to compile, update CUDA as well as your compiler to the latest versions you can install on your system. It is crucial that you update both, as newer CUDA versions are not always compatible with earlier compilers and vice versa. If your problem persists, consult the following table of known issues.

*After each step, delete the build folder and let CMake regenerate it before trying again.*

ProblemResolution
CMake error: No CUDA toolset found / CUDA_ARCHITECTURES is empty for target "cmTC_0c70f"Windows: the Visual Studio CUDA integration was not installed correctly. Follow these instructions to fix the problem without re-installing CUDA. (#18)
Linux: Environment variables for your CUDA installation are probably incorrectly set. You may work around the issue using cmake . -B build -DCMAKE_CUDA_COMPILER=/usr/local/cuda-<your cuda version>/bin/nvcc (#28)
CMake error: No known features for CXX compiler "MSVC"Reinstall Visual Studio & make sure you run CMake from a developer shell. Make sure you delete the build folder before building again. (#21)
Compile error: A single input file is required for a non-link phase when an outputfile is specifiedEnsure there no spaces in the path to instant-ngp. Some build systems seem to have trouble with those. (#39 #198)
Compile error: undefined references to "cudaGraphExecUpdate" / identifier "cublasSetWorkspace" is undefinedUpdate your CUDA installation (which is likely 11.0) to 11.3 or higher. (#34 #41 #42)
Compile error: too few arguments in function callUpdate submodules with the above two git commands. (#37 #52)
Python error: No module named 'pyngp'It is likely that CMake did not detect your Python installation and therefore did not build pyngp. Check CMake logs to verify this. If pyngp was built in a different folder than build, Python will be unable to detect it and you have to supply the full path to the import statement. (#43)

If you cannot find your problem in the table, try searching the discussions board and the issues area for help. If you are still stuck, please open an issue and ask for help.

Thanks

Many thanks to Jonathan Tremblay and Andrew Tao for testing early versions of this codebase and to Arman Toorians and Saurabh Jain for the factory robot dataset. We also thank Andrew Webb for noticing that one of the prime numbers in the spatial hash was not actually prime; this has been fixed since.

This project makes use of a number of awesome open source libraries, including:

Many thanks to the authors of these brilliant projects!

License and Citation

@article{mueller2022instant,
    author = {Thomas M\"uller and Alex Evans and Christoph Schied and Alexander Keller},
    title = {Instant Neural Graphics Primitives with a Multiresolution Hash Encoding},
    journal = {ACM Trans. Graph.},
    issue_date = {July 2022},
    volume = {41},
    number = {4},
    month = jul,
    year = {2022},
    pages = {102:1--102:15},
    articleno = {102},
    numpages = {15},
    url = {https://doi.org/10.1145/3528223.3530127},
    doi = {10.1145/3528223.3530127},
    publisher = {ACM},
    address = {New York, NY, USA},
}

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