Why is text resolution so bad in VR?

Question

VR is already at a point where it can render some impressive 3D landscapes. But it is awful at rendering text. This renders things like VR Desktop as basically unusable.

Question: Why is text resolution so bad in VR? I'm talking about from a technical standpoint?

EDIT: Here is a quote from an article about text resolution in VR:

“Text is tough in VR. It’s hard to read, given the resolution of today’s HMDs and it’s hard to write, since you’re typically blind in a headset and it’s annoying to be tied to a keyboard at a desk when you’d rather walk and move around in VR. I tolerate these problems with RiftSketch by making the text in the editor extremely large. I can only see 20 lines of code at a time in VR whereas my physical desktop has a 4K monitor where I’m usually looking at 140 lines of code per file with several files open side-by-side.”

My question is why, from a technical perspective, is this the case? If we can render i.e. Shrek in VR, why can't we render clear text?

Answer 1

Because the resolution is "bad".

I'm taking the Vive numbers and some numbers that are very rough estimates, they're pretty much identical to the Oculus Rift.

Each eye has a screen with a resolution of 1080x1200 and takes up more than a you can see without moving your eye. Your regular run of the mill monitor is 1920x1080 and takes up... let's say 2 thirds of your vision.

This leaves it with an effective resolution of 2880x1620, which is already quite a bit better.

Besides that, text rendering on a VR headset is typically done by rendering the text to a picture and then projecting that picture in 3D. This negates some of the advantages regular text has, namely the possibility to do anti aliasing on a known background and subpixel rendering.

It also adds the downside that you have to go through sampling again, which can introduce additional error.

Contrast this to rendering a model or a terrain. They have very little relevant detail. Just count all the little lines and curves in this text! Way less than a regular model and they are actually all important while a model just has to look close enough.