• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.1003-1006
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• 2005

Demand of Auto Focus for Camera module is increased very fast in these days and will be adapted to most of mobile phones in next few years instead of traditional method, fixed focus. To make auto focus function, 2 kinds of solutions, VCM(Voice Coil Motor) and Piezo linear motor are normally used. In this paper, VCM which commercially strong candidate for Auto focus mechanism was investigated to verify principles are match up to the actual operation. Auto focus algorithm is different between 1 chip and 2 chip solution. Normally 2 chip is more complicate than the other. To have best performance on this function, hysteresis and depth of field(DOF) table should be optimized.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.100.2-100
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• 2002

In this paper we propose a new visual servoing method for door opening with mobile manipulator. We use an eye-to-hand system that stereo camera is mounted on mobile platform, and adopt the position-based method. The previous methods for door opening mostly used eye-in-hand system with mono camera and required predefined knowledge such as radius and position about door grip, which was mainly caused by using mono cam era. This is also a severe constraint for pursuing general-purpose algorithm for door opening. For overcoming such drawback, we use stereo camera and suggest a new method that detect the door grip and estimate its pose from stereo depth information without predefined knowledge. Al...

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제33권1호
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• pp.31-43
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• 2015

This study had been aimed to conduct the camera calibration on VLBI antenna in the Space Geodetic Observation Center of Sejong City with a low-cost digital camera, which embedded in a mobile phone to determine the three-dimension position coordinates of the VLBI antenna, based on stereo images. The initial values for the camera calibration have been obtained by utilizing the Direct Linear Transformation algorithm and the commercial digital photogrammetry system, PhotoModeler $Scanner^{(R)}$ ver. 6.0, respectively. The accuracy of camera calibration results was compared with that the camera calibration results, acquired by a bundle adjustment with nonlinear collinearity condition equation. Although two methods showed significant differences in the initial value, the final calibration demonstrated the consistent results whichever methods had been performed for obtaining the initial value. Furthermore, those three-dimensional coordinates of feature points of the VLBI antenna were respectively calculated using the camera calibration by the two methods to be compared with the reference coordinates obtained from a total station. In fact, both methods have resulted out a same standard deviation of $X=0.004{\pm}0.010m$, $Y=0.001{\pm}0.015m$, $Z=0.009{\pm}0.017m$, that of showing a high degree of accuracy in centimeters. From the result, we can conclude that a mobile phone camera opens up the way for a variety of image processing studies, such as 3D reconstruction from images captured.

• Journal of the Institute of Convergence Signal Processing
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• 제15권2호
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• pp.30-36
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• 2014

Quality and resolution of camera in mobile device is improved significantly. In this paper, we propose block-based information hide techniques without image distortion for mobile device to solve image degradation in conventional watermarking methods. Information of image is composed with text such as camera maker, model, date, time, etc. Each text is converted to $8{\times}8$ pixel blocks and is added to the bottom of image. Generally image including block based information for image authentication are compressed using JPEG in mobile device. The vertical line value in JPEG header is modified by original size of image sensor. This technique can hide the block based authentication information using general decoder. In the experimental results, JPEG file size is slightly increased within 0.1% for the proposed block based authentication information encoding. Finally proposed methods can be adopted for various embedded systems using medical image, smart phone and DSLR camera.

• Journal of the HCI Society of Korea
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• 제7권2호
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• pp.49-56
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• 2012

The camera-based mobile applications such as color, pattern and object reading can improve the living quality of blind people. However currently available camera-based applications are uncomfortable for the blind, since these applications do not reflect accessibility requirements of the blind especially on touch screen. We investigated accessibility requirements about rapidly growing camera-based mobile applications on touch screen devices for the blind. In order to identify accessibility requirements, we conducted a usability testing for color reading applications with three different types of interfaces on Android OS. The results of the usability testing were as follows: (1) users preferred short depth of menu hierarchy, (2) the initial audio help was more useful than just-in-time help, (3) users needed both manual and automatic camera shooting modes although they preferred manual to automatic mode, (4) users wanted the OS supported screen reader function to be turned off during the color reading application was running, and (5) users required tactile feedback to identify touch screen boundary. We designed a new user interface for blind people by applying the identified accessibility requirements. From a usability testing of the new user interface with 10 blind people, we showed that the identified accessibility requirements were very useful accessibility guidelines for camera-based mobile applications.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.678-681
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• 2004

In this paper, efficient tracking of a moving object using optimal representative blocks is implemented by a mobile robot with a pan-tilt camera. The key idea comes from the fact that when the image size of moving object is shrunk in an image frame according to the distance between the camera of mobile robot and the moving object, the tracking performance of a moving object can be improved by changing the size of representative blocks according to the object image size. Motion estimation using Edge Detection(ED) and Block-Matching Algorithm(BMA) is often used in the case of moving object tracking by vision sensors. However these methods often miss the real-time vision data since these schemes suffer from the heavy computational load. In this paper, the optimal representative block that can reduce a lot of data to be computed, is defined and optimized by changing the size of representative block according to the size of object in the image frame to improve the tracking performance. The proposed algorithm is verified experimentally by using a two degree-of-freedom active camera mounted on a mobile robot.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.871-875
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• 2003

To detect and avoid obstacles is one of the important tasks of mobile navigation. In a real environment, when a mobile robot encounters dynamic obstacles, it is required to simultaneously detect and avoid obstacles for its body safely. In previous vision system, mobile robot has used it as either a passive sensor or an active sensor. This paper proposes a new obstacle detection algorithm that uses a stereo camera as both a passive sensor and an active sensor. Our system estimates the distances from obstacles by both passive-correspondence and active-correspondence using laser slit. The system operates in three steps. First, a far-off obstacle is detected by the disparity from stereo correspondence. Next, a close obstacle is acquired from laser slit beam projected in the same stereo image. Finally, we implement obstacle avoidance algorithm, adopting the modified Dynamic Window Approach (DWA), by using the acquired the obstacle's distance.

• Proceedings of the KSRS Conference
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.656-660
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• 2004

The Mobile Mapping System is an effective method to acquire the position and image data using vehicle equipped with the GPS (Global Positioning System), IMU (Inertial Measurement Unit), and CCD camera. It is used in various fields of road facility management, map update, and etc. In the general photogrammetry such as aerial photogrammetry, GCP (Ground Control Point)s are needed to compute the image exterior orientation elements (the position and attitude of camera). These points are measured by field survey at the time of data acquisition. But it costs much time and money. Moreover, it is not possible to make sufficient GCP as much as we want. However Mobile Mapping System is more efficient both in time and money because it can obtain the position and attitude of camera at the time of photographing. That is, Indirect Georeferencing must use GCP to compute the image exterior orientation elements, but on the other hand Direct Georeferencing can directly compute the image exterior orientation elements by GPS/INS. In this paper, we analyze about the positional accuracy comparison of ground point using the Direct Georeferencing and Indirect Georeferencing.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.331-334
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• 2002

In this paper, we present two types of vision algorithm that mobile robot has CCD camera. for obstacle avoidance. This is simple algorithm that compare with grey level from input images. Also, The mobile robot depend on image processing and move command from PC host. we has been studied self controlled mobile robot system with CCD camera. This system consists of digital signal processor, step motor, RF module and CCD camera. we used wireless RF module for movable command transmitting between robot and host PC. This robot go straight until recognize obstacle from input image that preprocessed by edge detection, converting, thresholding. And it could avoid the obstacle when recognize obstacle by line histogram intensity. Host PC measurement wave from various line histogram each 20 Pixel. This histogram Is ( x , y ) value of pixel. For example, first line histogram intensity wave from ( 0, 0 ) to ( 0, 197 ) and last wave from ( 280, 0 ) to ( 280, 197 ). So we find uniform wave region and nonuniform wave region. The period of uniform wave is obstacle region. we guess that algorithm is very useful about moving robot for obstacle avoidance.

• Journal of Institute of Control, Robotics and Systems
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• 제8권7호
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• pp.599-606
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• 2002

A new method to govern the navigation of a mobile robot using hand gesture recognition is proposed based on the following two procedures. One is to achieve vision information by using a 2-DOF camera as a communicating medium between a man and a mobile robot and the other is to analyze and to control the mobile robot according to the recognized hand gesture commands. In the previous researches, mobile robots are passively to move through landmarks, beacons, etc. In this paper, to incorporate various changes of situation, a new control system that manages the dynamical navigation of mobile robot is proposed. Moreover, without any generally used expensive equipments or complex algorithms for hand gesture recognition, a reliable hand gesture recognition system is efficiently implemented to convey the human commands to the mobile robot with a few constraints.