Hierarchical Route Maps for Efficient Navigation
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Hierarchical Route Maps for Efficient Navigation Fangzhou Wang 1 Yang Li 2 Daisuke Sakamoto 1 Takeo Igarashi 1,3 [email protected] [email protected] [email protected] [email protected] 1The University of Tokyo 2Google Research 3JST ERATO Igarashi Design Interface Project a b c Route&Tree Genera,on c b Figure 1: An example of Route Tree. The proposed algorithm automatically extracts meaningful multi scale views of a route and organizes those views into a hierarchical structure to support efficient navigation. (a) shows the original route and a complete overview of the Route Tree generated form the route, (b) and (c) show close-up view of the Route Tree. Note that these are visualization of the internal data structure and the end-users do not see them directly. ABSTRACT One of the difficulties with standard route maps is Author Keywords Route Map Visualization; View Extraction; Multi-scale accessing to multi-scale routing information. The user Navigation. needs to display maps in both a large scale to see details and a small scale to see an overview, but this requires ACM Classification Keywords tedious interaction such as zooming in and out. We propose H5.2 [Information interfaces and presentation]: User to use a hierarchical structure for a route map, called a Interfaces. - Graphical user interfaces; H.3.3 [Information “Route Tree”, to address this problem, and describe an storage and retrieval]: Information Search and Retrieval. - algorithm to automatically construct such a structure. A Retrieval models. Route Tree is a hierarchical grouping of all small route segments to allow quick access to meaningful large and INTRODUCTION small-scale views. We propose two Route Tree applications, A route map presents route information to guide users from “RouteZoom” for interactive map browsing and “TreePrint” one place to another. Various systems have been developed for route information printing, to show the applicability and for automatically generating route maps. These systems usability of the structure. We conducted a preliminary user have been conventionally implemented in car navigation study on RouteZoom, and the results showed that systems with a local map database. The use of web-based RouteZoom significantly lowers the interaction cost for route map generation systems, such as Google Maps [9], obtainingFigure 2: informationAn example fromof Route a map Tree. compared The proposed to a traditional algorithm automaticallyhas become extracts commonplace meaningful multi for scalevarious views types of a route of andusers interactiveorganizes map those. views into a hierarchical structure to support efficientrecently navigation as smart. (a) phoneshows sthe and original tablet route PCs andbecome a complete popular. overview of the Route Tree generated form the route, (b) and (c)Ho showwever, close several-up view usability of the Route problems Tree. Notestill remainthat these with are these visualization of the internal data structure andmap the systems.end-users do not see them directly. Permission to make digital or hard copies of all or part of this work for One problem with standard map systems is the lack of personal or classroom use is granted without fee provided that copies are support for presenting multi-scale information. For example, not made or distributed for profit or commercial advantage and that copies when users want to see an overview of the entire route, a bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. smaller scale view is preferred. On the other hand, when Abstracting with credit is permitted. To copy otherwise, or republish, to they want to get detailed information on points of interest post on servers or to redistribute to lists, requires prior specific permission (POIs) such as turning points or junctions, they would and/or a fee. Request permissions from [email protected]. prefer a larger scale view to see more details. However, IUI'14, February 24–27, 2014, Haifa, Israel. Copyright © 2014 ACM 978-1-4503-2184-6/14/02...$15.00. standard paper-printed route maps or interactive route map http://dx.doi.org/10.1145/2557500.2557514 systems in a modern map system [9, 19] require the user to manually change both scale and position in the map to get a desirable view, which can be very tedious. Therefore, it is information such as landmarks around them or the shape of desirable to provide an easy way to access various the road. Furthermore, the distorted representation makes it meaningful views with different scales and positions in the difficult to use the map in combination with advanced route. services such as aerial photo views. We propose to pre-compute a hierarchical structure for a Several existing web-based map systems [9, 19] are able to route map (called a “Route Tree”) to provide quick access print a step-by-step guide showing all POIs and to such meaningful views (Figure 1). The important corresponding verbal directions along the route. Karnick et features of our hierarchical structure are as follows: al. [16] proposed a method of putting detailed views of POIs in the route around the complete overview of the route. Feature 1. Each node represents a part of its parent view in This can be problematic because the user might want to see a larger scale, while the root node represents a complete the map in some intermediate scales. Furthermore, some of view of the whole route. the detailed views are almost the same and therefore Feature 2. For every part of the route, there is a node that redundant because the method shows a detailed view for visualizes the part in the necessary scale. each POI even in a case where it is possible to show multiple POIs in a single view. Feature 3. The number of nodes in the tree is made as small as possible, while keeping an appropriate view size Several previous studies [22, 25] attempted to exploit the (size of the rendered result on the screen or print) for each user’s prior knowledge about the route in order to produce a node. more simplified, useful route for users. Other studies [5, 11] propose methods that combine videos or images with We present an algorithm for automatically constructing a conventional route maps to enrich the user’s knowledge Route Tree. It starts with an over-segmented tree and about the route. There are also systems that generate Goal- iteratively simplifies it by taking balance between oriented route maps such as tourist maps [10] or compactness and readability. A Route Tree itself is raw tree Destination-oriented maps [18] rather than Start-to-Goal data, and it can be used in various applications. In this route maps. paper, we implemented an interactive map browsing system called RouteZoom to demonstrate the effectiveness of a Hierarchical map structure RouteTree. There are several studies on hierarchical structures for map Our method is designed to address the situation where a visualization. However, most of them discuss how to user needs to actively learn or explore an area or route. It is automatically make a series of multi-scale map images from different from but complements automatic uses of maps geographic data while including information in an systems such as Turn-by-Turn navigation used in car appropriate level of detail (e.g., [20, 27]). They do not use navigation in which a user passively receives step-by-step them for route map visualization. Studies have been made instructions from the system. The contributions of this work on hierarchical structures and route maps, but most of them are summarized as follows. focus not on visualization but on human cognition on routes and its application to generating verbal route directions [17, 1. A novel hierarchical structure for route maps called a 26]. Our work differs from these studies in that our method Route Tree. generates a series of maps with appropriate detail in 2. A fast algorithm to construct the Route Tree with a few different scales for a route map, and uses them for parameters given by the user to control the results. interactive browsing or compact printing. 3. Two useful route map applications that exploit Route Map browsing interface Trees, respectively improved a conventional route map Various methods have been proposed for interactively browsing system and a route map printing system. browsing maps in different scales. Some of them [2, 4] integrated maps of multiple scales into one screen using RELATED WORK Focus+Context techniques such as Furnas’ fisheye [7]. Route map visualization Others adopt Overview+Detail techniques to arrange Agrawala et al. [1] have proposed a system to render a route pictures of different levels of focus and size [12, 15]. map that mimics handwriting maps made by humans. This Another approach is to extend conventional panning and approach focuses on conveying precise information about zooming interfaces. Igarashi et al. [13] proposed a method POIs and an abstract overview of the complete route. To to automatically change zoom level depending on the achieve the goal, it distorts the geographic shape and length scrolling speed for map navigation. Zhao et al. [28] of the route and takes away detailed context around the proposed to implicitly bookmark user’s view on the map to route. However, the lack of contextual information outside accelerate browsing speed. Both of the latter two techniques the route makes it difficult for users to turn back to the rely only on general user input and do not leverage precise route when they mistakenly choose a wrong one, or semantic information associated with routes. Pindat et al. to determine their precise position in the route map from [23] proposed content-aware adaptive fisheye lens that changes its way of zooming depending on its focus on map.