# A Multilevel Road Alignment Model for Spatial-Query-by-Sketch
## 1 Introduction
The incomplete, distorted, and schematized features drawn in a sketch map are also challenges for SQbS, because the data quality can significantly affect the computation results. For example, [PERSON] et al. [16] found that the given hydrodynamic modeling process is sensitive to the changes of the qualitative aspect of the input data. [PERSON] and [PERSON] [17] developed cartographic visualization techniques to visualizing data uncertainty in the Database of Topographic Objects (DTO). In their work, three types of uncertainty (positional, attribute, and temporal) were presented using expert know-how and experiences. [PERSON] and [PERSON] [18] reviewed 90 empirical studies published since 1960 to identify the factors which can influence the quality of the sketch map. They found that among a lot of influence factors, some overlooked factors, such as source map characteristics and geographical education, are also of importance to the quality of sketch map. So, how to achieve the accurate alignment of the sketch map and other data sources is the focus of existing SQbS studies. Anyhow, most of the existing studies focus on the exact or constraint relaxation matching [19] of the objects' spatial relationships. For example, [PERSON] [6] advocated SQbS based on 9-intersection model for the first time. Then [PERSON] and [PERSON] [20] and [PERSON] [21] further demonstrated 9\({}^{+}\)-intersection relationships between directed line segments and between directed line segments and regions. [PERSON] et al. [22] extended the 9-intersection model by capturing metric details for line-line relations through splitting ratios and closeness measures. [PERSON] and [PERSON] [23] examined the topological relationships through a description of the boundary intersections between sets of objects. This approach preserved the ordering and qualitative length of these intersections. In particular, quantitative characteristics reflect individuals' direct cognition of places and play a key role in realizing a SQbS. Previous studies by [PERSON] et al. [24] reported that the spatial relationships among objects, including topological, order, and location relationships, are not completely consistent between sketch maps and metric maps owing to the presence of incorrectly sketched objects or those sketched in a distorted manner. Nevertheless, main roads, as the principal routes of regional traffic, exhibit a high similarity between sketch maps and metric maps, likely because people tend to draw main roads more frequently and accurately than the rest of roads in a sketch map. This aspect can be attributed to the fact that roads and paths connect places and are frequently used for navigation. This finding is consistent with the visual judgement of individuals, specifically, two places are deemed to be similar not only because they have similar spatial relationships but also because they have similar structural characteristics, such as shapes. The roads produced by the participants in the study by [PERSON] et al. [24] were drawn at a planning conceptualization level according to [PERSON] et al. [25]. The instructional or driver road conceptualizations did not appear maybe because participants were not asked to draw roads, but a place, so detail about road lanes, exits, or entrances was missing. The main goal of this paper is to enhance the correspondence between sketch maps and metric maps. For that, a novel matching approach termed Shape-based Spatial-Query-by-Sketch (SSQBS) is presented, which is based on a SQbS taking into account the road shape. A three-level road alignment model including individual roads, composite roads, and road scenes is developed. This approach is suitable for application to incomplete or distorted roads along with roads with an inconsistent topological relationship matching between the sketched maps and the metric maps. The remaining paper is structured as follows. Section 2 provides a review of the related work.