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1 Introduction

Wayfinding system is crucial for people to familiarize a strange environment. Wayfinding systems have been generally utilized inside of buildings, traffic roads and other public places. Traditional wayfinding systems rely on users’ visual ability, which means that users with normal visual ability will have great advantage of using traditional wayfinding systems. However, traditional systems are unfriendly to the visually impaired people since the visually impaired people are difficult to recognize the character and the pattern on the board. The design of traditional wayfinding board usually ignores the need of the visually impaired people. So there is an urgent need for designing wayfinding system specifically for the visually impaired people.

Nowadays, many studies have been done about the wayfinding system design for the visually impaired people. These studies can be classified as indoor systems and outdoor systems according to the application scenario. In order to compensate for the visual ability reduction of the visually impaired people, some supplementary devices are needed, like GPS [1, 2], camera [3, 4] and robots [5,6,7]. GPS provides position service for the visually impaired people. Combined with digital map, GPS has been used as a method for helping the visually impaired people. Camera-aided methods mainly utilize the mechanism of image processing. The camera of smart phones takes the picture of current environment and by image processing the location of the user can be obtained. Some studies chose the specially designed image related to current environment, which reduces the complexity of computation. Robot-aided methods utilize robots to guide the visually impaired people. The robot gets the position information of the destination by smart algorithms.

However, all these methods have some disadvantages under the circumstance of indoor wayfinding. Firstly, indoor wayfinding requires high level precision of positioning since a small error of positioning will lead to a different place considering the small size of indoor environment. The precision of GPS in indoor scenario needs to be improved, thus limiting its application potential in the indoor environment. Secondly, camera-aided methods usually require installing additive APPs on the smart phone. In addition, the management department of the indoor space needs to develop the backstage program of the APP and maintain its operation. The overall procedures are too complex and the cost is high. At last, robot-aided method is expensive and the design of robot is relatively complex. In conclusion, a low cost, easily maintained and effective wayfinding system for the visually impaired people is extremely urgent under current circumstances.

The design of a system or a service needs principle. Service design theory not only considers the service process but also supporting resources like human resources and technical challenges [8]. Currently service design theory has been applied in many fields like APP design [10], Web design [11] and O2O design [12]. Tools of service design theory include service blueprint [9, 13] and quality function deployment [14, 15].

In this paper, a color related and QR code enhanced wayfinding system is proposed to meet the demand of the visually impaired people. The proposed system is designed based on the service design theory and has the advantage of low cost, easily upgraded and high added value. Main innovations of this system can be listed in the following aspects:

  1. 1.

    The proposed system is designed based on service design theory. It fully utilized the information contained on the traditional wayfinding board. Detailedly speaking, the relation of background color and destination is established in this system. Moreover, the QR code is added on the wayfinding board to transfer information from the wayfinding board to the smart phone. The system fully utilizes the residual visual ability and hearing ability of the visually impaired people.

  2. 2.

    The proposed system can be upgraded smoothly from current wayfinding system. This characteristic saves the time of developing and deploying new system. Current infrastructure could be fully utilized.

  3. 3.

    The proposed system is of low cost. No other additive devices are needed except for the commonly used smart phones. In addition, no other specifically APPs need to be developed. And the backstage maintain is easy to be conducted.

2 Visual Ability Experiment

The visually impaired people are not fully blind. The target group of people in this system is not blind people. Even though the visually impaired people may not distinguish the detail of a pattern, they can still recognize some visual elements. An experiment was conducted by our group to find the visual ability of the visually impaired people in order to guide our design. 104 volunteers were invited to participate in this experiment including 85 nearsighted people and 12 people who have cataracts and 7 people who have glaucoma. Since visual impairment is a decreased ability to see to a degree, the invited volunteers were asked to take off their glasses or aided devices when participating in the experiment.

Volunteers of nearsighted people were mainly from college students. Cataract patients and glaucoma patients were invited from the blind massage company, who were hired by the blind massage company. Average age of volunteers is 24.8 and the average visual acuity level is 4.13, measured by the International standard vision chart.

2.1 Recognition Ability Experiment of the Visually Impaired People

In this experiment, different recognition abilities for the wayfinding board pattern detail and boundary were tested. Although the content of the wayfinding board is relatively difficult for the visually impaired people to recognize, the shape of the pattern boundary seems distinguishable.

The experiment was conducted in separate places. 85 nearsighted volunteers were mainly colleague students. They could be easily gathered and the experiment could be conducted in one specific place. 19 cataracts and glaucoma people were separated in different places and their experiment was conducted by visiting them face to face.

During the experiment, the volunteer was asked to clarify both the content and the boundary of the pattern on the wayfinding board at a distance of 0.5 m, 1 m and 1.5 m. The provided wayfinding board is designed with the size of 10 cm * 30 cm. The content was designed with different content complexities, as shown in first line of Fig. 1. The characteristic of these wayfinding boards is that the boundary is relatively simple when the content is complex.

The complexity of the content could be quantificationally described using the principle in the field of image processing. The complexity of a image could be calculated using the ratio \(\mathrm{R}_{\mathrm{edge}}\). \(\mathrm{R}_{\mathrm{edge}}\) is the ratio of boundary pixel amount to the amount of all pixels, which is shown in Eq.  (1).

$$\begin{aligned} \mathrm{R}_{\mathrm{edge}}=\mathrm{P}_{\mathrm{edge}}/(\mathrm{m}*\mathrm{n}), \end{aligned}$$
(1)

\(\mathrm{P}_{\mathrm{edge}}\) is the number of pixel in the content boundary, m is the number of pixels on the column and n is the number of pixels on the row. Higher \(\mathrm{R}_{\mathrm{edge}}\) represents higher level of content complexity. From the Eq.  (1), the boundary of the content should be detected first. The Sobel operator was used as the method to detect image boundary. By MATLAB simulation, the detected boundary was shown in the second line of the Fig. 1. From left to the right, \(\mathrm{R}_{\mathrm{edge}}\) of these images is 0.0369, 0.0175, 0.0206 and 0.0314, which basically suits the experience of visual eyesight. During the experiment, the wayfinding board was placed at different heights in order to match the volunteers’ height. The volunteer was asked to recognize different wayfinding boards at different distances, 0.5 m, 1 m and 1.5 m. A successful recognition of pattern content and boundary was recorded. After experimenting with 104 volunteers, the result was listed in Table 1.

Fig. 1.
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Experiment material and boundary detection results

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Table 1. First part experiment results
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From Table 1, the success rate of content recognition is basically lower than the boundary. The success rate of content and boundary is increasing with the decreasing of the distance between the volunteer and the wayfinding board, since smaller distance can help the volunteer clarify the pattern on the wayfinding board more clearly. With the increase of the ratio of the edge, the success rate of content is decreasing. However, the success rate of boundary recognition is nearly the same when at different ratios of the edge. This is because that the shape of the boundary is almost regular and is not related to the content of the pattern.

From the experiment, it can be concluded that the visually impaired people still have some visual abilities. Although the visually impaired people have difficulty in distinguishing the content of the pattern on the wayfinding board, they can still clarify the boundary of the pattern. This means that the visually impaired people can locate where the image is if provided with a frame in a regular shape. This conclusion can be utilized for guiding the design of the wayfinding board for the visually impaired people.

2.2 Visual Learning Ability Experiment

People have abilities for learning from the experiment. When facing a strange environment, they may learn from the visual elements contained in the environment. We can all imagine the situation that when we are in a strange situation and provided with a new wayfinding system with different patterns, an adaptation process is progressed. When a pattern on a wayfinding board is witnessed for a second time, the time needed for us to recognize it reduces in a large extent. The visual learning ability experiment is aimed at testing people’s learning ability of the strange wayfinding board.

In this experiment, different patterns with different background colors were prepared as experiment material. The experiment contained two parts. For the first part, the volunteer were asked to clarify the content on the wayfinding board. Each volunteer was asked to take 3 rounds of experiment, each round is equipped with a specific kind of wayfinding boards with the same background color. The background color of the wayfinding board in different rounds is different. In this experiment, three colors were taken as the three rounds’ color. In each round of the experiment, 3 wayfinding boards were prepared with different content on the board. And the testing sequence of the 3 boards in the same background color is their permutation sequence, which means that each experiment board was shown 6 times. All the testing boards’ patterns and characters are shown in Fig. 2. During the first part of the experiment, when the volunteer gave the wrong answer about the content of the board, the correct answer would be given to the volunteer. And a successful recognition of content would be recorded. For the second part of the experiment, each volunteer was provided with 20 wayfinding boards with different background colors and contents to recognize. The sequence of the experimenting materials was not predefined. All the 20 wayfinding boards were contained in the first part of the experiment. At this part, the correct answer would not be given if a wrong answer was shown. Through this two steps experiment, we aim to test the visually impaired people’s ability to establish the relation between content and background color.

Fig. 2.
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Experiment material of the second round experiment

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The result of first step experiment is shown in Fig. 3. From Fig. 3, it can seen that the success rate of recognition is increasing with the increasing rounds of experiment. This is because the volunteer gradually adapted to the new system through the correct answer. After average 3 rounds of experiment, the success rate reached over 70%. At the second step of the experiment, the overall success rate remained around 65%. Compared with the first round test in the first round experiment, the success rate of recognition improved a lot. Whats more, the wrong answer of the volunteer was also recorded. It can be found that around 89% of the wrong answer lied in the set of the rest wayfinding boards in the same background color. Through this experiment, it can be concluded that the visually impaired people have the ability to adapt to the new wayfinding system. And the relation of color and content can be gradually established by several rounds of training.

Fig. 3.
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The success rate of recognition increases with the round of the experiment

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2.3 Button Size Experiment for the Visually Impaired People

The visually impaired people still use smart phones. From our observation of the our invited volunteers, cataracts and glaucoma people also use smart phones but their face is much closer to the screen than the normal eyesight people. Since our design consider using the smart phone as the platform, the ability for the visually impaired people to use smart phones needs to be verified. In this experiment, the visually impaired peoples ability to correctly press a button is experimented.

During the experiment, the volunteer was asked to press the button on the screen on the smart phone in a distance of normal eyesight button. If the button is correctly pressed, an indication voice will be provided. Different sizes of patterns were designed as experiment materials. The result of the experiment was shown in Table. From Table 2, it can be shown that the success rate of pressing the button is increasing with the increase of the pressing number. And the shape of the button is not a decisive reason for the success rate. It can be found that the success rate reached around 90% when the experiment time reached 5. Thus, it can be concluded that the visually impaired people could still have the ability to use smart phone UI with a relatively large size button.

Table 2. Second part experiment results
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3 Proposed Design

Based on the conclusion obtained from the experiment, we propose a new wayfinding system. The proposed system contains color related system and the QR code enhanced system. The color related system utilizes the potential relationship between the pattern and the color, which makes it convenient for the visually impaired people to search information for the destination. The QR code enhanced system is the extension for the color related system. The QR code enhanced system provide vocal guidance for the visually impaired people and by using the smart phone, the information can be heard repeatedly. The proposed system utilized the residual visual ability of the visually impaired people and provide more service through hearing sense.

3.1 Service Touchpoint Analysis of the Wayfinding System

When designing the wayfinding system, the wayfinding board could not just be viewed as a product, but as a service. The service is to provide wayfinding information the visually impaired people. By applying the service design theory, the optimization of service touchpoint is conducted to optimize the service experience and improve service quality. In traditional wayfinding service, the service touchpoint mainly relies on the visual sense. The background color is to make the character and pattern more visible. The character is to illustrate the information about the destination. The pattern is to give a vivid illustration about the destination. For the backstage operation, the backstage maintaining is simple and only needs regular clearance. However, from the view of service design, traditional service has some disadvantages. The visual service touchpoint is not fully utilized since the background color is not fully utilized. In addition, the pattern and character is not easy for the visually people to recognize. What’s more, the update about the destination information is difficult. Rebuilt of the wayfinding board is inevitable. The service blueprint of traditional wayfinding system is shown in Fig. 4.

Fig. 4.
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Service blueprint of traditional wayfinding system

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3.2 Color Related Wayfinding System

Traditional wayfinding system utilizes the background color to make the character and pattern more visible. However, this mechanism has little effect among the visually impaired people since they have low ability to distinguish the detail. According to the service design theory, this phenomenon indicates that visual service touchpoint is not fully utilized. In the color related system, the relationship between the background color and destination pattern is established. One background color relates to one specific destination. According to our experiment, the visually impaired people has the ability to establish the relationship. An illustration of the proposed color related system is shown in Fig. 5. The color related system has several advantages. The relationship of color and destination reduces the level of needed visual ability. The user only needs to differentiate the color to find which item of the wayfinding board is needed. In addition, the sequence of items on the wayfinding board may be different at different places. The user has to recognize all the items on the board to find the needed one in the traditional system. In the proposed system, this problem could be easily solved. What’s more, the proposed system is both helpful for the normal eyesight people and the visually impaired people. And the colorful wayfinding board is environmentally friendly.

Fig. 5.
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Color related wayfinding system

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3.3 QR Code Enhanced Wayfinding System

QR code has been widely used in current society. In China, thanks to the development of smart phones, the QR scanner APP has been an integrated APP. In the QR code enhanced system, the QR code is used as a channel for transferring the user from the wayfinding board to the smart phone. One QR code is placed on one item of the wayfinding board. The user could scan the QR code and get an UI on the smart phone. The user could press the button on the UI to get vocal guidance to the destination. An illustration of the proposed QR code enhanced system is shown in Fig. 6. According to the conclusion obtained from our experiment, the visually impaired people has residual visually ability to recognize the boundary of the pattern and press the button. This conclusion makes the QR code enhanced system feasible. The proposed QR code enhanced system has several advantages. The hearing service touchpoint is exploited to provide additional channel for the information transportation. In addition, the proposed system suits the visual ability of the visually impaired people. Whats more, extension of the smart phone UI is easy to conduct and the backstage maintenance is convenient.

Fig. 6.
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QR code enhanced wayfinding system

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3.4 Service Blueprint

The proposed service blueprint is illustrated in Fig. 7. From the Fig. 7, it can be found that the proposed service has more service touchpoints and the utilization of the service touchpoint is improving.

Fig. 7.
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Comparison of traditional and proposed service blueprint of wayfinding systems

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4 Conclusion

A new wayfinding system was proposed in this paper. The system used the color to carry more information about the destination and a sound guidance is constructed using QR code. All the devices needed is a smart phone with QR scanning function. So the implementation is low cost and easy to update. The future work of this direction is that the UI interface could be updated. For example, the AR/VR could be used to guide the direction of the destination.