Portable Augmented Reality installation with hologram special effect for kids’ education to learn everyday objects

. The utilization of Information Technology has a great opportunity to be explored to support students in learning the materials. Presentations can help students learn new content more effectively, especially for children learning everyday objects. Learning can be made more interesting, memorable, and participatory by using Augmented Reality technology. Holograms are a hybrid of Augmented Reality and Virtual Reality, often used in amusement park rides. Generally, visitors can feel their emotions while riding the rides, and these recollections are preserved in their memories. Based on the benefits of AR and hologram special effects, researchers combined the "wow" effect of these things. They created a solution in education by using a hologram special effect and combining them with AR technology. When combined interactively with AR technology, the hologram special effect is predicted to become a good teaching approach. This solution aims to develop a portable AR installation with hologram special effects on a low budget, making it viable to apply in education and capable of helping students learn creatively.


Background
Education has adopted Information Technology (IT) to support the process of student to learn something.The utilization of IT that been use at a various stage of the learning activates mental processes such as perception, attention, memory, and thinking [1].The learning process can be concluded as successful if the students are able to remember the subject/material they have learned so they can be applied in the real world.The occipital lobe of the human brain plays a critical role in human memory by recording and processing information that is visually seen by the eye [2].
Presentation (to explain the new material to students) is able to optimize the learning process [1].The application of IT in education provides numerous opportunities to expand the presentation technology so the students can be facilitated in absorbing new information/material.
Hologram object projection can display virtual objects in realistic, as if they were in the actual world.The hybrid elements of Augmented Reality (AR) and Virtual Reality can be called as Mixed Reality-based hologram [3].A hologram is a three-dimensional (3D) projection of an object that can be seen by everyone without using a special device such as 3D glasses.This condition provides a chance for researchers to apply hologram to assist students in learning without the requirement of special devices/tools that need to be used by the user.
In real life, the implementation of hologram (hologram special effect) has been used on rides in amusement park.This special effect adopts the optical illusion principle which manipulates human vision and brain.By experiencing this effect on the rides, visitors usually astonish and able to feel more their emotions.As a result, these moments will be captured and stored in their memory [4][5].
It would be amazing if the "wow" effect felt by the visitors at amusement park can be applied in education by using IT to help students absorb new information and remember them longer compared to learning with conventional method.Hologram special effects is very promising to be applied in education.
The implementation of AR in education can make learning more fun, memorable, and interactive [6][7].Based on these advantages, hologram special effect if combined with AR technology is able to create * Corresponding author: seraphina@binus.ac.id interactive hologram solution.This solution is believed to have a very good combination to be integrates as a teaching method.Hologram special effect solution with AR is expected to help students to be able to learn in a unique way to make the learning process fun and help them to remember information longer compared with a conventional learning.The purpose of this research is to make a portable AR installation with hologram special effect by using affordable budget so it is feasible to be implemented in education and the benefits can be felt by many students.The scope of learning material in the research focused on kids education to learn everyday objects: window (the opening in the wall or other things).

Related works
A special effect on Pepper's ghost optical illusion is produced by reflected light [8].This technique is used in amusement parks, theatres, movies, museums, and other places since 1862.This optical illusion uses realworld object or recorded image that is reflected on a transparent panel at 45° angle.This illusion is able to display a virtual image on a transparent screen and has the depth of real-world objects.This virtual image can also be mixed with real elements to create a livelier impression [8][9].Pepper's ghost optical illusion installation can be seen in Fig 1.The Encyclopedia Britannica defines AR as ''the use of computer modelling and simulation to enable a person to interact with an artificial three-dimensional (3-D) visual or another sensory environment'' [10].In literature review, there is a lot of research that that focus on AR, especially in science education.Shelton and Hedley [11] observed the effect of AR on geography students' to understanding the relationship between Earth and Sun.At the end of the study, it concluded that AR technology had a positive effect on students to understanding the subject.AR technology has capabilities to enhance the class more interactive, enjoyable, and knowledgeable [7,12].
There are 3 types of holography used in education: pseudo holograms, analog holograms, and digital holograms [13].Pseudo hologram is generally used more frequently in classrooms because it requires simpler and more convenient technology.According to Fodikes' study, the installation needs the use of a laptop, tablet, and a pyramid to project the hologram [14].Laptops and tablets need remote management software installed to control another device.Students choose a video from laptop, which is later projected onto a tablet, and finally onto a pyramid.

Methods
The method used in this research uses a pseudo hologram and inspired by related works that have been carried out by previous researchers [14].Because the target is to make a portable AR installation with hologram special effects, the tools or devices used need to be selected properly (portable enough and need to be simple).
Smartphone is portable device and a very promising solution to be used in this research [15].Smartphone can be imagined as portable computers that is capable to receive the input from the user, able to process data, and display the result on the screen.
There are several types of AR.Generally, the method used in marker-based type AR requires a camera as an input.Smartphone already embedded with camera.AR technology can be applied in smartphone without other additional tools that need to be connected.A special application needs to be developed to process the captured object from the camera.Web-based application was chosen by researcher for convenience reasons because the application does not need to be installed on a smartphone.It can work by using a browser that is usually installed on a smartphone.The application required to recognize the object (marker) by using computer vision technology.The smartphone's camera detects the object and then calculates the position and orientation of the marker to position the virtual object.Cloud is used to as a method to store all object's information and application (cloud-based server).If the application successfully recognizes the object, the information will be sent to the smartphone.As a result, a virtual object/information will be shown on the smartphone's screen.
Usually, sensors in smartphone (in example: gyroscope, accelerometer, Global Positioning System/GPS) will be used to calculate the captured object and to provide AR output/result.Researchers do not use the information from these sensors since the smartphone placed on the top of the transparent panel and user do not need to hold the smartphone.To make a hologram special effect for portable AR installation, a transparent panel is needed.The transparent panel made from thin acrylic panel and the angle needs to be set at 45°.The transparent panel need to be put inside the dark color box that has an opening on the top.Smartphone need to be put on the top of the box with the screen facing downwards.As the results, the reflection of virtual object from the smartphone's screen will be shown on the transparent panel and user will see a hologram object.A flowchart of the method for creating a portable AR installation with hologram special effect is illustrated in Fig. 2.

Results and discussion
Fig. 3 is the installation design and architecture based on the methods discussed in section 3.All the requirements (especially cloud-based server and AR application: AR maker application/custom AR system-client AR System [15]) need to be set first.AR applications can be developed in-house or can use the application from the previous research.Research was conducted by following the steps in Fig. 4. The research intended to make a portable AR installation with hologram special effect solution, so the size of the transparent panel and the box need to be small enough to be carried.As a starting point, this solution is suitable for one person.
The box made has 0.1cm thickness and has the following size: 6cm x 7.5cm x 7cm.The transparent panel used has a size of 5.9cm x 9.85cm with a thickness of 0.5cm.These panels are positioned at a 45°angle and should fit inside the box.The color of the box (especially the inner side of the box) needs to use a dark color so let the reflection of the virtual object can be seen more clearly.Marker-based AR needs an object as a marker.This research uses an object from building block toy because it can be assembled and dismantle to fit the learning material.Researchers made a window shape object out of building block toy and take a picture from the front of the window to create a marker.The light of the taken image need to be bright enough to let the application recognize the object easily.Later, the image was cropped to fit the edge of the window (Fig. 5).The cropped image inserted in the working area in the AR maker application towards z axis (facing up).All the virtual objects (all texts/images/videos) were arranged.The rules for arranging the virtual object are needed to face up and flipped because the result of the projected virtual objects will be reflected on the transparent panel (Fig. 6).Researchers recommend virtual objects to use bright color to make them stand out to the dark color box.If the design for AR output already been created, the results will be stored in the cloud-based server and the application will create a custom Uniform Resource Locator (URL) or link.The link can be opened in a browser on a smartphone to view the AR results.
The smartphone's screen must display a browser that has accessed the link provided by the AR creator application.The smartphone must be placed on top of the box with the screen facing down.The object (window made from building block toy) needs to be hold above the smartphone's camera.Make sure all areas of the object that are photographed as marker are captured by the camera.If the object is recognized, the virtual object that has been designed will appeared on the smartphone's screen.The brightness of the smartphone's screen is recommended to be set to the highest value to make the output displayed on the screen can be reflected on the transparent panel.The solution has been tested to get the "formula" and setting for the best result.Fig. 7 is the implementation's result of portable AR installation with hologram special effect.

Conclusion and recommendation
A portable AR installation with hologram special effect for education has been successfully implemented by combining AR technology (marker-based AR) and hologram special effect (using transparent panel) with the help of smartphone.The transparent panel need to be put inside the dark color box (with the opening on the top) at 45° angle and the virtual objects created by using A maker application are recommended to use bright color.Building block toy can be used as an object because it can be easily assembled and dismantle to fit the learning material.
This research solution has a limitation.Because the box and the device (smartphone) used are small to keep it portable, the solution is only suitable for one person at a time.As a result, if there are other students who wish to study together, they will be unable to see the output of the AR by using special effect hologram.The recommendation for further research is to create an installation that can address this limitation and still keep the installation portable.

Fig. 3 .
Fig. 3. Installation design and the architecture of the solution.

Fig. 4 .
Fig. 4. Step by step how the research was conducted.

Fig. 5 .
Fig. 5. Marker of window object made from building block toy.

Fig. 6 .
Fig. 6.The design to create an AR output.

Fig. 7 .
Fig. 7.The result of the implementation.