OMiCroN -- Oblique Multipass Hierarchy Creation while Navigating

TL;DR

OMiCroN introduces a fast, memory-efficient algorithm for building hierarchical point cloud data structures that enables immediate partial rendering, significantly improving streaming visualization workflows.

Contribution

It is the first algorithm capable of instant partial visualization of sorted point clouds during hierarchy construction, reducing time and storage costs.

Findings

Builds hierarchies in memory comparable to reading from disk

Enables immediate partial rendering of point clouds

Supports streamed, incremental visualization workflows

Abstract

Rendering large point clouds ordinarily requires building a hierarchical data structure for accessing the points that best represent the object for a given viewing frustum and level-of-detail. The building of such data structures frequently represents a large portion of the cost of the rendering pipeline both in terms of time and space complexity, especially when rendering is done for inspection purposes only. This problem has been addressed in the past by incremental construction approaches, but these either result in low quality hierarchies or in longer construction times. In this work we present OMiCroN -- Oblique Multipass Hierarchy Creation while Navigating -- which is the first algorithm capable of immediately displaying partial renders of the geometry, provided the cloud is made available sorted in Morton order. OMiCroN is fast, being capable of building the entire data structure in memory spending an amount of time that is comparable to that of just reading the cloud from disk. Thus, there is no need for storing an expensive hierarchy, nor for delaying the rendering until the whole hierarchy is read from disk. In fact, a pipeline coupling OMiCroN with an incremental sorting algorithm running in parallel can start rendering as soon as the first sorted prefix is produced, making this setup very convenient for streamed viewing.