This is an improvement to standard cascaded shadow maps that was developed by Intel a while back. It more effectively allocates the cascades to where the detail is needed. Notably in my testing with the associated test app its often able to strongly reduce or even eliminate the shimmering that otherwise occurs in scenes with moving light sources. A 7-zip containing the paper is attached along with a link to it and the slides for a presentation on it.
https://dl.acm.org/doi/abs/10.1145/1944745.1944761
https://www.intel.com/content/dam/develop/external/us/en/documents/sampledistributionshadowmaps-siggraph2010-notes-181237.pdf
SampleDistributionShadowMaps.7zip