Empty tiles should have for @2x layers 512x512px about tileserver-php

[daliborjanak]

I think that it is better to compute size of empty tile from "scale" attribute from tilejson (or compute it if it's not set). It's not good to define tile size in layer name. I thing it is not logical. Users do not want to know if it's retina or not they just want to see a map.

[klokan]

Correct.

The only problem is that "scale" in metadata does not always must have the meaning the tile has more pixels (see my description at openlayers/openlayers#1905)

But it does have this meaning for MapTiler generated tiles which is enough for us right now.
Let's go for an implementation based on the "scale" in metadata of the layer.

[daliborjanak]

Ok. We can also create attribute "scale" if it it's not set in metadata - detect size of one tile and compute...

[klokan]

Let's go for an implementation based on the "scale" in metadata of the layer.