Settings: low / med / high (/ ultra) - how are they chosen?

I'm trying to wrap my head around HDRP quality settings (LOD, shadows, etc).

A new empty HDRP scene comes with three quality profiles (HDRP High Fidelity, Balanced, and Performant). But then when you're trying to adjust quality, and you look at rendering, lighting, and other settings, they're further divided into Low/Medium/High sections, or sometimes Low/Medium/High/Ultra sections, as below:








My question is - how can you tell which of these is getting used when the game is running?

Back in the old days, there used to be three Tiers, but those have been deprecated in SPR land.

And yet, I'm testing this on a fairly normal desktop PC - and the game seems to be picking "low" all the time, which is very confusing.

Unfortunately documentation seems completely silent on this point, e.g. HDRP Asset docs, Frame Settings docs.

Has anyone figured this one out?

 

There's ad order of how and where Quality settings are arranged.

The highest level is the SRP assets themselves.
These are mostly targeting hardware features to enable/disable.
You shouldn't change these at runtime at a live game state ( like a pause menu).

You can run the editor at only one of these at a time, similarly a server one at a time.

Next down the line your have the component quality features, like you mentioned DOF quality.
This is something in editor you can change on the component in the inspector, or in a game quality setting at runtime ( like a pause menu)
You tune the samples and quality at the asset level.

Below that you have the component settings themselves that you see in the inspector, but these all have the ability to choose the Quality from the asset in use ( these can be changed at runtime)

So to answer your question
how can you tell which of these is getting used when the game is running?

In editor you'll run the profile you have chosen as default from your list of assets.

And you'll run the quality settings of the component you have chosen it it's inspection respectively.

If we take DOF as an example again.
Click on your hierarchy object with a DOF component, look at its inspector, you'll see
Focus mode
Quality

The quality settings will be low med high custom.

These reflect the low med high you're mentioning that are within your active SRP asset back in project settings

 

Ok, I see now how this works. In case someone is googling for this in the future - in short, the low/med/high choices is a way for quality settings assets to communicate with cameras, lights, etc.

In the end it's a powerful system - cameras, lights, and volumes can set their quality to be abstractly high medium or low, and then a separate quality asset specifies what it means concretely in terms of texture sizes etc. And then the game can switch between different quality assets for high-end or low-end computers, or consoles, etc.

For example, you want one scene to have high quality shadows, but then in another scene you don't. So you set the light in the first scene to use shadow map resolution "high", and in the second a light with shadow map "low". And then in the quality settings asset you can set "high, medium, low" to be 4k, 2k, 1k textures respectively. But then you want to add support for low-end machines - so you can add another quality settings asset and map "high medium low" to be 1k, 512, 256, or whatever, and let the player switch those in the options menu.

You can also do the same with cameras, volumes, etc. To set different LOD per camera, you set the defaults in the HDRP Global Settings one way (e.g. set LOD bias quality level "high") and then on a specific camera check the box "custom frame settings", and override it (e.g. set LOD to "low"). And similarly as above, then the quality setting asset can define what that means - high-end asset could map high/medium/low bias to be 3/2/1, while low-end asset could map to 1/1/0.5 and so on.

What makes this extra confusing is that 1. high/medium/low are very generic names - and also arbitrary - which makes googling hard, 2. how these are hooked up between quality assets and cameras/lights/volumes/global settings is completely not obvious, and 3. it's also not documented in HDRP docs.

Basically the only place I've seen this actually explained by Unity is the Unite Now 2020 video which is highly recommended:

 

Worth checking out the Ebooks as well