Simple I/O-efficient flow accumulation on grid terrains
Data Structures and Algorithms
2012-11-09 v1
Abstract
The flow accumulation problem for grid terrains takes as input a matrix of flow directions, that specifies for each cell of the grid to which of its eight neighbours any incoming water would flow. The problem is to compute, for each cell c, from how many cells of the terrain water would reach c. We show that this problem can be solved in O(scan(N)) I/Os for a terrain of N cells. Taking constant factors in the I/O-efficiency into account, our algorithm may be an order of magnitude faster than the previously known algorithm that is based on time-forward processing and needs O(sort(N)) I/Os.
Keywords
Cite
@article{arxiv.1211.1857,
title = {Simple I/O-efficient flow accumulation on grid terrains},
author = {Herman Haverkort and Jeffrey Janssen},
journal= {arXiv preprint arXiv:1211.1857},
year = {2012}
}
Comments
This paper is an exact copy of the paper that appeared in the abstract collection of the Workshop on Massive Data Algorithms, Aarhus, 2009