At the beginning of 2020, Unity finally and officially integrated the HDRP High-Definition Rendering Channel. Excellent news for all video game lovers and developers who use this engine. Next, we will talk about our pleasant experience with the use of this tool in the Negroponte Home project (an architectural environment in virtual reality) using version 2019.3.1. We will explain a little about the environment adjustments with the Global Volume tool, light and shadow adjustments, and finally its integration with Substance Painter for the development of materials.
Global Volume
The base setting for lighting in HDRP is through Global Volume, which allows us to load images in HDR for direct and indirect incidence on the lighting of the entire scene. Having to be adjusted proportionally with the Exposure (exposure) of the HDR on the scene, and the Fixed parameter, which in our case, gives us a higher contrast of the image output levels.
To generate changes in tone on the HDR, emulating a twilight or simply simulating a camera filter, it is beneficial to use an image editor such as Photoshop with Photographic Filter adjustment, because in this way, faster results will be achieved and with better control about HDR.
An element that generates depth in the scene and also helps to associate the different objects in it, is the Fog option, and not only for large and wide environments, but also in small spaces. It is critical to match the color of the Fog with the incidence of the overall HDR color.
Finally, and in a similar way to a photographic retouching process, in HDRP an adjustment of color or Color Curves is performed to generate more contrast between the tones and their black and white levels, thus highlighting shadows and highlights either in a general or specific color channels.
Lights and shadows
The workflow for integrating lights into an environment in Unity is similar to the flow of any 3D modeling package like Maya or Blender. After the HDR base setting, lights are integrated, in our case a Directional Light that emulates the Sun. From this light, which has a higher incidence, the shadows are projected by adjusting the Resolution (shadow resolution) to 2048 * 2048 and blurring with the Normal Bias.
The use of Area Lights allows us to blur and emulate the attenuation of natural light when entering a closed space, thinking that it will be lighter as it approaches the window and darker if it moves away from it. Also, Area Light allows us to emulate a bounce of light to illuminate specific areas in order to have a clearer environment. In our case, the shadows of these lights were deactivated since they are a reinforcement to the global illumination.
The Light Layers adjustment provides us with an ideal solution to isolate specific points to be illuminated, or also to highlight them in case the initial light adjustment is not enough. In the Negroponte Home project, Light Layers is applied to metallic objects such as beams.
Materials with Substance Painter
A program that has made our lives easier is undoubtedly Substance Painter, which gives us ease and power when creating different materials and shaders. In addition, its integration with Unity allows an optimal and agile workflow.
When creating materials, it is important to define their response to light, in this case being an architectural environment, the analysis of real objects is important. The previous assembly of a moodboard allows us to better organize the materials to be used for the subsequent adjustment of the specular, reflective, refraction and / or roughness level.
Although in Unity there are parameters for the adjustment of the Ambient Occlussion or AO a greater contrast can be given from the same Substance Painter by generating a Fill Layer (solid layer) with the AO map created at the initial moment of baking of all the object maps, and merge it using the Multiply blending mode.
As of the Substance Painter 2020.1 release, there are HDRP Material Export Presets that save us time when exporting texture maps.
Once all the texture maps have been imported into Unity, the materials are created to integrate each of the textures. It is important to check the incidence of light in the scene on the different materials and to integrate the Reflection Probe around the reflective objects, since its visualization can differ drastically in Unity, and sometimes it is mistakenly deduced that Substance Painter exported wrongly maps. To correct the behavior of materials in light of light, the levels of Smoothness Remapping and Ambient Occlussion Remapping must also be adjusted.
Conclusion
In conclusion, the HDRP High-Definition Rendering Channel has all the necessary features to generate hyper-realistic environments with a varied set of settings and possibilities. And best of all, it offers a wide variety of solutions for the different needs of the industry, from the realization of simple flow projects, to the development of AAA games.
And although some adjustments are missing to be integrated that will surely do so in the new versions, our experience in Negroponte Home with the HDRP High-Definition Rendering Channel, allows us to highly recommend the use of this tool that has marked a before and after in the development of interactive digital systems.
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