Asset creation process
Windows Mixed Reality builds on the decades of investment Microsoft has made into DirectX. This means that all of the experience and skills developers have with building 3D graphics continues to be valuable with HoloLens.
The assets you create for a project come in many shapes and forms. They can be comprised of a series of textures/images, audio, video, 3D models and animations. We can't begin to cover all the tools that are available to create the different types of assets used in a project. For this article we will focus on 3D asset creation methods.
Concept, creation, integration and iteration flow
Things to consider
When looking at the experience you're trying to create think of it as a budget that you can spend to try to create the best experience. There is not necessarily hard limits on the number of polygons or types of materials use in your assets but more a budgeted set of tradeoffs.
Below is an example budget for your experience. Performance is usually not a single point of failure but death by a thousand cuts per-se.
Total number of assets
- How many assets are active in the scene?
Complexity of assets
- How many triangles / polygons?
- How complex is the shader?
Both the developers and artists have to consider the capabilities of the device and the graphics engine. Microsoft HoloLens has all of the computational and graphics built into the device. It shares the capabilities developers would find on a mobile platform.
The creation process for assets is the same regardless of whether you're targeting an experience for a holographic device or an immersive device. The primary thing to note is the device capability as mentioned above as well as scale since you can see the real world in mixed reality you will want to maintain the correct scale based on the experience.
We'll start with the ways to get assets for your project:
- Creating Assets (Authoring tools and object capture)
- Purchasing Assets (Buying assets online)
- Porting Assets (Taking existing assets)
- Outsourcing Assets (Importing assets from 3rd parties)
First you can create your own assets in a number of different ways. 3D artists use a number of applications and tools to create models which consist of meshes, textures, and materials. This is then saved in a file format that can be imported or used by the graphics engine used by the app, such as .FBX or .OBJ. Any tool that generates a model that your chosen graphics engine supports will work on HoloLens. Among 3D artists, many choose to use Autodesk’s Maya which itself is able to use HoloLens to transform the way assets are created. If you want to get something in quick you can also use 3D Builder that comes with Windows to export .OBJ for use in your application.
There is also the option to capture objects in 3D. Capturing inanimate objects in 3D and editing them with digital content creation software is increasingly popular with the rise of 3D printing. Using the Kinect 2 sensor and 3D Builder you can use the capture feature to create assets from real world objects. This is also a suite of tools to do the same with photogrammetry by processing a number of images to stitch together and mesh and textures.
When you purchase assets from a 3rd party you always want to check the following:
- What's the poly count?
- Does it fit within your budget?
- Are there levels of detail (LODs) for the model?
- Level of detail of a model allow you to scale the detail of a model for performance.
- Is the source file available?
- Know what you're getting
- Are animations provided?
- Make sure to check the contents list of the asset you're purchasing.
In some cases you'll be handed existing assets that were originally built for other devices and different apps. In most cases these assets can be converted to formats compatible with the graphics engine their app is using.
When porting assets to use in your HoloLens application you will want to ask the following:
- Can you import directly or does need to be converted to another format? Check the format you're importing with the graphics engine you're using.
- If converting to a compatible format is anything lost? Sometimes details can be lost or importing can cause artifacts that need to be cleaned up in a 3D authoring tool.
- What is the triangles / polygons count for the asset? Based on the budget for you application you can use Simplygon or similar tools to decimate (procedurally or manually reduce poly count) the original asset to fit within your applications budget.
Another option for larger projects that require more assets than your team is equipped to create is to outsource asset creation. The process of outsourcing involves finding the right studio or agency that specializes in outsourcing assets. This can be the most expensive option but also be the most flexible in what you get.
- Clearly define what you're requesting
- Provide as much detail as possible
- Front, side and back concept images
- Reference art showing asset in context
- Scale of object (Usually specified in centimeters)
- Provide a Budget
- Poly count range
- Number of textures
- Type of shader (For Unity and HoloLens you should always default to mobile shaders first)
- Understand the costs
- What's the outsourcing policy for change requests?
Outsourcing can work extremely well based on your projects timeline but requires more oversight to guarantee that you get the right assets you need the first time.