DirectX11.2 enables native hardware support for virtual texturing through tiled resources. This allows developers to generate sparse texture arrays by only allocating memory as required. One application for tiled resources is sparse shadow maps, a technique for improving on shadow maps.
Texture space is subdivided into a grid of tiles but some tiles are allowed to be missing and no physical memory is allocated for these missing tiles. This is implemented through a page table allowing developers to map and un-map tiles as needed. More information on Tiled Resources is available here.
Sparse Shadow Maps
Shadow maps are a nearly ubiquitous feature of modern game engines, however they tend to suffer from artifacts caused by a mismatch between view and light space resolutions. A sparse texture can be considered a variable-resolution representation where tiles missing at a given level, indicates that data is presented at a coarser LOD. Using a sparse shadow map the developer is able to place resolution where required in order to get high quality results in a reasonable amount of memory.
Find out more
This technique was presented by Cem Cebenoyan (Director of Engineering, NVIDIA) at GDC 2014 in a presentation entitled Real Virtual Texturing - Taking Advantage of DirectX 11.2 Tiled Resources.
All of the NVIDIA GDC 2014 presentations are also available.