Abstract: Horizon Zero Dawn presented the Decima engine with new challenges in rendering large and dense environments. In particular, we needed to be able to quickly query a very large set of potential objects to find which should be visible. This talk looks at the problems we faced moving from more constrained Killzone levels to Horizon's open world, and our approach to fast visibility queries using the PS4's asynchronous compute hardware. It also covers our recent work on efficiently collecting batches of object instances during the query to reduce load on the entire rendering pipeline. A basic familiarity with GPU compute will be helpful to get the most out of this talk.