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Oculus Quest Development with Houdini Unity and USD

Oculus Quest Development with Houdini, Unity and USD

Part One

This is the first in a series of articles where I look at Oculus Quest Development with Houdini, Unity, and USD. USD is Pixar’s comprehensive scene format, Universal Scene Description. I first saw the power of USD a few years ago during a Pixar demonstration that showed its power. For example, it was able to render scenes with 20+ million polygons in real-time. Now that Houdini 18 has Solaris, which is built on USD, it is now possible to easily read and write USD files.

Oculus Quest Development with Unity

First, let’s look at the Oculus Integration package in Unity. We want to make sure that we have the correct settings. In my examples, I am working in Unity 2019.3.f6. First, I always switch the platform to Android when creating a new project for the Quest. Next, I set the texture compression to ASTC. This can take time depending on how many textures there are in the project.

Oculus Quest Player Settings in Unity

 

Next, we want to make sure the player settings are correct. With the player settings open we want to make sure of the following:

  • Remove the Vulkan API from the Graphic APIs
  • Color Space is set to Linear
  • That you have the Oculus SDK installed in the XR settings.

Stereo Rendering Mode – I have Single Pass selected. I have this based on that Multi-Pass has been broken so far. Oculus released a new version February 6th but I have not yet tested Multi-View

Installing USD in Unity

Installing Universal scene description is easy. First, go to window / package manager. This will open Unity’s Package Manager. Under Advanced, we need to make sure that show preview packages are checked. Lastly, now that we have preview packages selected, all we have to do is install USD. Find USD in the list and click install.

Lastly, if you don’t want to use the Package Manager you can always pull from Unity’s USD Git Hub

Once USD has been installed, a new USD menu will appear. This is where we can import and export USD files.  Unity gives us the option to import a USD as a game object, a prefab,or a timeline clip. Furthemore, Unity gives us the option to export USDZ,the zipped format for USD.

USD in Houdini with Solaris

Other Houdini Tutorials:

Point Transformations  in Houdini

Point Transformations  in Houdini

In this introductory tutorial, we look at point based transformations in Houdini. As well, we will look at attribute-based point transformations. For example, attributes can be color, normals, velocity, or anything else. Point transformations are fundamental for many effects created in Houdini. Above all, position in Houdini is just an attribute. As a result, we can manipulate it like any other attribute. Using a VOPs based approach we will look at the Mix VOP. For example, the Mix VOP will allow us to mix two vectors, and then blend between them. Moreover, Houdini has the unique ability to operate on the point level. As well, Houdini has the ability to embed any attribute on points. Therefore, we can blend anything from position, color, and normals. In truth, we can blend whatever we like. Lastly, we will look at how we can use this with a copy to points and metaballs. We will look at how we can adjust the display settings to view the metaballs correctly. In Conclusion, the user should have a solid understanding of:

  • Using Scatter to keep consistent point counts.
  • Basic VOPs Skills.
  • Blending Attributes.
  • Using the Copy to Points.
  • Using Metaballs in Houdini.
  • A better understanding of vectors in Houdini.

This tutorial will provide a basic understanding of VOPS in Houdini. For Example, VOPS allows us to visually place nodes in place of Code. VOPS stands for Vex Operators. Vex is Houdini’s internal language for creating and manipulating geometry.

You can download a free version of Houdinihere

Other Houdini Tutorials:

Curves in Houdini

Curves In Houdini

In this tutorial we examine curves in Houdini. Curves are an essential part of 3D modeling. Houdini has the unique ability to work between NURBS curves and polylines seamlessly. For instance, with NURBS we are able to embed attributes along the parametric curve like UV. We can then easily convert the curves to polylines, maintaining any attributes. We can then use VOPS or VEX based methods for controlling new attributes. In addition these can drive any number of things. This makes it possible to manipulate any attribute we want. This can control things like object instancing, scale along the curve, or any number of other effects. It is also possible to maintain a consistent point count between the two types. Maintaining a point count is imperative to creating good tools that can create objects at a variety of resolutions. Houdini also has the typical curve tools. Lastly, we examine how to set up common operators. For example, common operators are nodes like revolves and other curve based effects, like sweep and carve.

After this one should have a solid understanding of:

  • The Curves tools in Houdini
  • UV attribute on Curves
  • Making shapes with Revolves
  • Extruding along a path correctly
  • Carving with Curves that have UV attributes

Once you have a solid understanding of curves in Houdini you will be able to create numerous effects and tools.

You can download a free version of Houdini here.

Other Houdini Tutorials:

Real-Time Point Clouds Zed Mini

Real-Time Point Clouds with the Zed Mini

Lately, I have been experimenting with real-time point clouds with the Zed Mini from Stereolabs. Firstly, I am a big believer in real-time point clouds being a viable solution for co-located, virtual reality experiences. Concurrently, I am also interested in examining the development of this technology, and how we use artificial intelligence and machine learning to examine the world we live in. The Zed Mini functions much in the same way that the Kinect Azure does. The big difference is that the Kinect is more plug and play, while the Zed needs external libraries. Lastly, another big difference is the image and point-cloud quality, with the Zed being far superior. For some people, the fact that some of the tools need to be built using CMake and Visual Studio will be a deal-breaker. Stereolab provides resources in their Git Repository.

The Zed Tools

After I built the tools from the source, I now have access to some tools in samples/bin. As an example, the most immediately useful is ZED_SVO_Recording.exe. Firstly, this allows me to write an SVO file to disk. SVO is a proprietary format from Stereolab. Most importantly, this format allows for the recording of all the data from the Zed camera into a compressed file format. This will allow me to construct the point-clouds after shooting. In order to run these tools, I need to call them from the command-line. For ZED_SVO_Recording the only argument I need is a path to where I want the SVO file saved. So assuming I am in the shell in the correct directory, you would just write:

ZED_SVO_Recording.exe c:SVO_save_folder/mySVOFile.svo

The prompt should start scrolling frame numbers, and a ctrl-c will break the operation. One the SVO is saved, one can use some of the other tools that Stereolab provides.

Zed in Touchdesigner

I am working with a friend, Shaoyu Su to get TensorFlow and YOLO working through the Zed and Touchdesigner for object recognition and tracking.

You can download a free version of Touchdesigner here:

Other Houdini Tutorials:

Introduction to Houdini Digital Assets

Introduction to  Houdini Digital Assets. In this tutorial, we will examine the fundamentals of creating a simple H.D.A. As an example, we will create a tool that will make procedural I-beams of any size. In addition to being able to adjust the shape and size of the i-beam, the tool will automatically UV our object. Lastly, once the tool is finished it can be imported into Unity or Unreal Engine. Therefore we can use our tool in any application that takes an H.D.A. As a result, we will be able to create any i-beam of any size and use them however we want. In conclusion, Houdini Digital Assets are a great way to create tools for use in other applications. This lets us build modular reusable assets. This is a very quick introduction to show how easy it is to make a useful asset in Houdini. This will show you the basics of:

  • Linking parameters
  • Auto UV Maps
  • How to Build a simple interface in Houdini
  • How to correctly name and save H.D.A’s

Once you have done this tutorial one should have a solid basic understanding of Houdini Digital Assets and can explore further tutorials to increase your skills.
This is as a follow up to a lecture for a class I teach in Houdini. This is so the students can re-cap the in-class lecture. I apologize for any lack of polish. Hopefully, there will be some good information there.

You can download a free version of Houdini here.

Other Houdini Tutorials:

Lidar with Ouster and Touchdesigner

Real-Time Lidar with Touchdesigner and Ouster

I have been wanting to experiment with real-time lidar using the newer, small Ouster Units and Touchdesigner. The last time I did any experiments with real-time lidar it was with a Velodyne 16. Using Touchdesigner we can now easily use lidar that runs in real-time. Ever since I first got to play with that Velodyne 16, I have been an advocate of the point cloud as a means of geometry display. Points are light in memory and can contain their RGB information. Because of this, it is far easier to display real-time evolving data than it would be to try to mesh, UV and texture. Even as a post-process the very concept of meshing will always be subject to artificating and resolution problems.

Lidar Compared Depth Based Techniques

Currently, real-time Lidar solutions lag behind any depth-based solution like a Kinect Azure or a Zed Camera in regards to a resolution. As well, we do not yet get any RGB data. Moreover, to get RGB data we would need an additional device, such as a small Virtual Reality camera. However, we do get an intensity value. This acts like a black and white image.

Testing

One of my students was able to get a loaned out OS2, a $16,000 unit so that he can use it in his Masters Thesis at USC School of Cinematic Arts. We used the Lidar with the Ouster running through Touchdesigner. Touchdesigner has an Ouster Top and Chop that allows us to pull in all the data. The unit has the following specs:

  • The OS0 lidar sensor: an ultra-wide field of view sensor with 128 lines of resolution
  • Two new 32 channel sensors: both an OS0 and OS2 version
  • New beam configuration options on 32 and 64 beam sensors

Volumetric Video

You can see some of my research with Google and the Foundry here. I believe this is how we will eventually represent large, realistic datasets for both virtual and augmented reality. Self-driving car and machine learning have brought us smaller, better and faster lidar and I am seeing the technology trickle down into interesting alternative use cases.

Intensity Pass

These images below show the full image range of a normalized “intensity” pass.

Other Houdini Tutorials:

Instancing Geometry with Touchdesigner

Instancing with Touchdesigner

In an introduction to instancing geometry in Touchdesigner, I show how we can instance geometry on the GPU.  Instancing allows us to create multiple copies of an object. Since they are just copies, we can create a large number of copies. Moreover, we can give them random scale, coloring, and rotation for variety. In Touchdesigner we use  CHOPS, and now TOPS in order to provide channels for instance. As a result, we can alter and change the instances over time.
An introduction to instancing geometry in Touchdesigner will provide a basic understanding of:

  • How we can generate channel data for Instancing in CHOPS
  • How we use that data on a Geometry Container

You can download a free version of Touchdesigner here.

Other Houdini Tutorials: