Data from: On the Helmert-blocking Technique: its acceleration by Block Choleski decomposition and formulae to insert observations into an adjusted network

The Helmert-blocking technique is a common approach to adjust large geodetic networks like Europeans and Brazilians. The technique is based upon a division of the network into partial networks called blocks. This way, the global network adjustment can be done by manipulating these blocks. Here we show alternatives to solve the block system that arises from the application of the technique. We show an alternative that optimizes its implementation as the elapsed processing time is decreased by about 33%. We also show that to insert observations into an adjusted network it is not necessary to readjust the whole network. We show the formulae to insert new observations into an adjusted network that are more efficient than simply readjusting the whole new network.

赫尔默特分块法（Helmert-blocking technique）是平差欧洲大地测量网、巴西大地测量网等大型大地测量网的常用方法。该方法的核心是将整体大地测量网划分为若干被称为“分块”的局部子网，借此可通过对这些分块进行操作完成整体网平差。本文针对应用该技术所产生的分块方程组，给出了多种求解方案。其中一种优化方案可将处理耗时降低约33%，实现了运算效率的优化。此外，本文证实，向已完成平差的大地测量网中加入观测值时，无需对整个网络进行重新平差；同时推导了可向已平差网中添加新观测值的计算公式，该方法的运算效率远高于直接对包含新观测值的整体网络重新平差的方案。