ABSTRACT

Point feature label placement (PFLP) has been a fundamental problem in automatic cartography over decades. In this research, labels are approximated by individual characters to offer more freedom of placement on raster-based grids, including allowing labels turning to avoid occlusions. Considering that parallel orientation of label annotation increases the label chances to resolve the dense conflicts, and that hexagonal grids provide more orientations than square grids, this study uses a parallel annotation to conduct point label placement on hexagonal grids, which is efficient to figure out high-quality label placement for points of interest (POI). The approach introduces a detailed representation of point feature labels on hexagonal grids. Then an algorithm of label placement on hexagonal grids is presented, using the methodology of parallel annotation to arrange labels with different combinations of label orientations. The approach is fast and flexible due to the pre-computed grid and maintains good readability due to the parallel annotation.

摘要

数十年来，点要素标签的放置（PFLP）一直是自动制图的基本问题。在这项研究中，标签由单个字符近似，以提供更大的放置在基于栅格的网格上的自由度，包括允许标签转向以避免遮挡。考虑到标签标注的平行方向会增加标签解决密集冲突的机会，并且六角形栅格比方形栅格提供更多的方位，因此本研究使用平行标注在六角形栅格上进行点标签放置，这可以有效地找出高度质量的兴趣点标签（POI）。该方法引入了六边形网格上点特征标签的详细表示。然后提出了在六角形网格上放置标签的算法，使用平行注释的方法来排列标签方向不同的标签。由于采用了预先计算的网格，因此该方法既快速又灵活，并且由于并行注释而保持了良好的可读性。