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Color quality evaluation is key to judging map quality, which can improve data visualization and communication. However, most existing methods for evaluating map colors are tedious and subjective m...

Creating appropriate colour schemes is challenging for both novice and experienced cartographers. This paper introduces an artificial bee colony (ABC) algorithm to automatically create various colo...

Creating a satisfying qualitative color scheme from scratch may be difficult for novice mapmakers and experts. A probability-based method is proposed to identify knowledge regarding qualitative color selection from readily available color schemes and formalize the discovered knowledge to assist in color creation. An unsupervised method to extract the general trends of color selection is presented, and the issue of qualitative color selection is translated into a multi-constraint optimization problem. A feasible solution for achieving the global optimum is then provided. A probability-based method is also proposed to match abstract color values with specific mapping features. This proposed approach is evaluated in a case study. The results of the case study suggest that the proposed method allows users to create qualitative color schemes more efficiently and confidently.

Maintaining topological consistency is a crucial issue for 3D cadastral modeling as this helps to represent the cadastral boundary clearly and accurately. As a result, 3D cadastral data models are mainly built on the basis of topological models that allow topology to be expressed clearly. However, topological models in Euclidean space cannot directly represent objects&rsquo, geometric information. As geometric information is important in 3D spatial analysis, 3D cadastral data models based on topological models cannot realize topological calculation and analysis. Previous research has proved that geometric and topological information for cadastral objects can be integrated and represented by conformal geometric algebra (CGA) expressions. This paper aims to realize 3D topological analysis in the cadastral field using CGA&rsquo, s advantages in geometric relations computation. A calculation framework is designed on the basis of the outer product to achieve the purpose of multidimensional unity for 3D cadastral topological analysis in this paper. A calculation framework of topological relations between a boundary point (or a boundary line) and a cadastral parcel is developed. A total of 13 types of topological relations between a boundary point and a cadastral parcel and 48 types of topological relations between a boundary line and a cadastral parcel are obtained. The study indicates that the advantages of CGA in multidimensional unified representation and calculation can be used to solve problems encountered by topological models in Euclidean space.

Polygonal data often require rendering with symbolization and simplification in geovisualization. A common issue in existing methods is that simplification, symbolization and rendering are addressed separately, causing computational and data redundancies that reduce efficiency, especially when handling large complex polygonal data. Here, we present an efficient polygonal data visualization method by organizing the simplification, tessellation and rendering operations into a single mesh generalization process. First, based on the sweep line method, we propose a topology embedded trapezoidal mesh data structure to organize the tessellated polygons. Second, we introduce horizontal and vertical generalization operations to simplify the trapezoidal meshes. Finally, we define a heuristic testing algorithm to efficiently preserve the topological consistency. The method is tested using three OpenStreetMap datasets and compared with the Douglas Peucker algorithm and the Binary Line Generalization tree-based method. The results show that the proposed method improves the rendering efficiency by a factor of six. Efficiency-sensitive mapping applications such as emergency mapping could benefit from this method, which would significantly improve their visualization performances.

Symbol is one of the cores of GIS and mapping system. However, difference of design styles, data structures, storage methods and render strategies among the systems leads to no synchronous sharing of map symbols when sharing geographic data. Taking map symbols as a breakth-rough, the paper analyzes and compares the ArcGIS symbol model with the SLD and provides the mapping mechanism between ArcGIS symbols and SLD symbols to study the symbol sharing between them. The analytic result shows that the SLD symbols all can be converted to the ArcGIS symbols, but only small part of ArcGIS symbols can be converted to the SLD symbols. The ArcGIS symbol system is more consummate but not perfect and the closed symbol format goes against to symbol sharing. And the SLD symbol format is open, but it is too unitary to meet the needs of Cartography. Therefore, a common symbol model is required to synthesize ArcGIS symbols and SLD symbols to achieve the map symbol sharing.

Symbol and data are two cores of GIS and mapping systems. However, with the full sharing of geographical data, symbol information is not shared synchronously and there is a large number of low-level duplication in the process of making symbols. Based on symbol sharing problem among different systems, point symbols will be taken as a breakthrough to study symbol sharing between CAD and GIS, and to provide the mapping mechanism from CAD symbols to TrueType fonts. Experiment validates the feasibility of sharing between CAD blocks and TrueType-based GIS point symbols and offer approach for one map symbol library with multi-usage.