Most underwater intelligent vehicles and marine remote-control vehicles are equipped with optical cameras for underwater imaging. However, due to the properties of water and its impurity, the quality of the images taken by these imaging devices is not good enough, because the water weakens the light, and the deeper the water, the more the intensity of the light will decreases. Since different wavelengths show different behavior in the collision with the water column, processing and study of these wavelengths is very important to obtain the desired image. The spectral signature can be used for underwater applications. In this research, to increase the quality of underwater images, a new method has been introduced to improve image contrast. In this method, first, with structured lighting, different wavelengths are irradiated to the underwater target in a laboratory environment, then underwater images are processed by the proposed algorithm, and finally, a multispectral image is achieved by stacking images with different wavelengths. The results showed the relative superiority of the proposed method over other methods. Manuscript profile

One of the major strengths resulting from hyperspectral imaging is target detection, specifically subpixel detection, which is generally carried out without full knowledge of the targets to be detected. The aim of this study is to design and develope a hyperspectral camera and then testing its results in hidden target detection domain. For this purpose, a coin was hidden under a cloth in a laboratory environment and then was take hyperspectral imaging of the hidden target. Initially, the images were labeled in terms of wavelength and band and geometric corrections and used for final processing. In order to detect image anomalies, the RX algorithm was used locally to identify pixels that are spectrally different from other pixels. To identify hidden target material, spectra of extracted as anomalies pixels were extracted and by using of the spectral library, hidden target material was identified. The accuracy of the extracted spectra was evaluated by the spectral angle, ACE , Likelihood and FP correlation methods and the results showed high accuracy of the target material identification process. Manuscript profile

Nowadays, various systems and, tools have been used to study the components of the atmosphere. In atmospheric correction of satellite images, it is necessary to identify and use the specifications of the atmosphere during satellite crossing. For this purpose, in this research, designed and constructed an optimal sun-photometer system to determine the local atmospheric parameter. LabVIEW environment has been used to record Aerosol Optical Depth (AOD) data and guide motors in two axes for accurate sun tracking. In this research, by calculating the aerosols optical depth and studying its behavior on different days, two CCD (Charge-Coupled Device) and CMOS (Complementary Metal–Oxide–Semiconductor) sensors have been compared to record data. A comparison of the two sensors under the same conditions showed that the responsibility of the CCD sensor is more linear than the CMOS sensor. To evaluate the performance of the designed sun-photometer system, the MODIS sensor data of Aqua and Terra satellites were used. The results showed the high capability of the developed system in measuring AOD in comparison to MODIS AOD data. By comparing the CCD and CMOS sensor data with the Terra satellite data, 80% and 71% data matching, respectively, are observed. Manuscript profile

Radiometric errors are the most common errors of data acquired by remote sensing sensors. Correction of this type of error requires knowledge about the atmospheric conditions during imaging of the sensor. The aim of this study is to select an ideal location for the construction of a radiometric calibration site. Tehran province was selected as a case study to conduct research in a pilot environment. Based on the studies performed on the CEOS standards in site selection as well as the criteria observed in Cal Val sites, 14 parameters were selected as important and necessary parameters for calibration site selection. The data used in this research include two categories of satellite data and GIS layers. After applying the preprocessing on the data and obtaining the weight of each layers, suitable places were obtained for the construction of the calibration site between 2012 to 2019 years. Due to the importance of the consistency of the selected place during different years, the places that were always suitable between the evaluated years, were selected. The results of the research show an ideal location in the western region of Tehran for site construction, which has been selected very well suitable in terms of all criteria. In addition to developing the appropriate location for the calibration site uses, instruments such as san-photometer and goniometer were also developed to be installed on the site to provide services to multispectral and hyperspectral sensors. Manuscript profile

Conventional cameras based on an array of pixels (CCD or CMOS) are commonly used to capture a target image at a certain distance. In this type of camera, all pixels are used to create the image. For CCD-based cameras at other wavelengths, including infrared and terahertz, having all the pixels increases the cost of the camera. The aim of this study is to design and build an imaging setup using a single pixel method to reduce the cost of the camera and to reconstruct the target image using less data. We verify this method for visible band due to availability of visible light equipment that can be generalized this method to other wavelengths. We use a spatial light modulator (SLM) produces two-level optical masks with random distribution with 20 x 20 pixels and a size of 10 x 10 cm and illuminates the target at a repetition rate of 1 Hz. The reflection of each mask from the target captured by a CCD camera and then we average of all pixels of the CCD to equate it with a single-pixel detector. The target image is reconstructed using a compressive sensing algorithm. The process of reconstructing the target image is performed using a minimum number of masks. We use the two norms L1 and TV to retrieve the target image. The simulation results show norm TV is more successful in target image retrieval. Also, with increasing the number of masks, the success rate in retrieving the target image increases. Manuscript profile

Most smart and unmanned aerial vehicles use optical imagers for imaging and distance measurement. But in the foggy environment, the quality of the images taken by these systems is not good enough and there is even a possibility of destroying the images. Because the light gets scattered in contact with water vapors and fog and destroys the image recorded in the imager. Therefore, image processing is very important in these systems, but in heavy fog, distance measurement faces a serious problem. Other alternative methods are generally not economical or efficient. In this article, a new method is introduced for distance measurement and imaging on the sea surface. This method scans the environment by using two stereo imagers whose optical axis is parallel and a linear laser located on one of the cameras, and using trigonometric relations, the difference of light lines recorded in the imagers is calculated and the image and sample 3D is created from the environment. The analysis of the obtained results shows that the system is able to measure the distance of the environment with an error of less than one centimeter, and due to the type of arrangement of imagers and laser, it overcomes the effects of fog in the images with a much lower cost than other hardware. Manuscript profile

اعمال تصحیحات اتمسفری به‌منظور کاهش اثرات مخرب اتمسفری بر کیفیت و صحت داده‌های ثبت‌شده، نیازمند دانش جامعی از شرایط، ویژگی‌ها و رفتار اتمسفر به هنگام گذر سنجنده در مختصات هدف است. امروزه تجهیزات، مدل‌ها و الگوریتم‌های بسیاری جهت مطالعه و بررسی مؤلفه‌های اتمسفری استفاده می‌شود. بدین منظور در این تحقیق به طراحی و ساخت سامانه بومی تابش‌سنج خورشیدی جهت محاسبه عمق اپتیکی هواویز‌ها اقدام گردید. به‌منظور شبیه‌سازی و بررسی اثرات ناشی از تغییرات هر مؤلفه اتمسفری از مدل MODTRAN در محیط PCModWin استفاده شد. در این سامانه الکترواپتیکی در دو طول‌موج 450 و 550 نانومتر، به دلیل محدوده جذبی هواویزها، در دو روز متفاوت ازنظر میزان آلاینده موجود در اتمسفر، داده‌های شدتی ثبت گردید. به‌منظور اطمینان از یکنواختی و خطی بودن پاسخ‌دهی سامانه الکترواپتیک طراحی‌شده در اندازه‌گیری تغییرات شدت نور خورشید، به کالیبراسیون رادیومتریک این سامانه اقدام گردید. با استفاده از مدل‌های اتمسفری، از داده‌های شدتی ثبت‌شده، عمق اپتیکی هواویز و میزان‌نمایانی افقی اتمسفر محاسبه شد. به‌منظور صحت سنجی و ارزیابی عملکرد سامانه طراحی‌شده، از داده‌های عمق اپتیکی به‌دست‌آمده از سنجنده MODIS(Aqua) و داده‌های نمایانی افقی ایستگاه هواشناسی فرودگاه مهرآباد تهران استفاده گردید. نتایج ارزیابی صحت، نشان داد که محاسبه عمق اپتیکی توسط سامانه طراحی‌شده و سنجنده MODIS(Aqua) هردو در ساعت گذر ماهواره عدد 0.5 را نشان می‌دهد. همچنین نتایج نشان‌دهنده همبستگی خوب نمایانی افقی محاسبه‌شده در این تحقیق با داده‌های به‌دست‌آمده از ایستگاه هواشناسی مرجع می‌باشد. Manuscript profile

مناطق مرزی به‌عنوان یکی از مهم‌ترین گلوگاه‌های امنیتی هر کشوری محسوب می‌شوند. نظارت و پایش مداوم این نواحی به‌عنوان یکی از اولویت‌های اصلی نیروهای مرزبانی و یکی از مؤلفه‌های اصلی تأمین امنیت این نواحی است. با پیشرفت‌های به وجود آمده در فناوری‌های تصویربرداری فضایی و هوایی، عملیات پایش مرزها با سرعت و دقت بیشتری انجام‌گرفته است. کشور ایران به دلیل گستردگی خطوط مرزی و همچنین وجود گروه‌های تروریستی متعدد در اطراف مرزهای خود، به‌عنوان یکی از کشورهای مخاطره پذیر مرزی شناخته می‌شود که شناسایی و دفع این خطرات بالقوه و بالفعل نیاز به اشراف اطلاعاتی نسبت به وقایع تهدیدکننده در این نواحی دارد. بر اساس نیازهای نیروهای مرزبانی به‌منظور شناسایی مسیرهای عبور و مرور اشرار و گروه‌های تروریستی، در این تحقیق، روشی به‌منظور کشف و شناسایی رد عبور وسایل نقلیه با استفاده از تصاویر SAR چند زمانه ارائه گردیده است. ابتدا تصاویر مورداستفاده به لحاظ پیش‌پردازش‌های موردنیاز و وجود خطاهای ذاتی تصاویر SAR اصلاح گردیدند و در مرحله بعد با استفاده از اطلاعات فاز و الگوریتم Coherence Change Detection(CCD)، رد عبور خودرو در تصاویر شناسایی گردید. به‌منظور ارزیابی قابلیت روش پیشنهادی، روش‌های معمول آشکارسازی تغییرات نیز بر روی تصاویر اعمال شد. نتایج تحقیق نشان‌دهنده قابلیت بالای روش پیشنهادی در شناسایی کریدورهای عبور و مرور غیرمجاز مرزی است. نتایج این تحقیق می‌تواند به‌عنوان یکی از مؤلفه‌های تأمین امنیت در مرزهای کشور مورداستفاده قرار گیرد. Manuscript profile

Background and objective: Absolute and Relative Models of Radiometric Corrections Due to the relative information provided from different parts of the globe, there are always errors when correcting images, which has led many researchers to develop local models or design tools to obtain information about the situation of Atmospheric of the area under study when the satellite passes. The present study aims to present a new method for radiometric correction of satellite images.Material and methods: To apply the proposed method for correcting the calibration of satellite images, a sun-photometer was first designed and developed that can obtain atmospheric data and attenuate sunlight in the range of 400 to 950 nm in a hyperspectral mode. Sentinel-2 satellite images related to the city of Tehran were selected as a sample and in 2 days with clean and high pollution, data were obtained and the coefficients obtained were applied through a sun-photometer.Results and conclusions: Based on made assessments, the importance of radiometric corrections based on local information for satellite images become more apparent. Evaluation of the research results shows the high capability of the designed sun-photometer in accurately assessing the attenuation of sunlight in different spectral. The amount of sunlight attenuation in the green band is more than the blue and red bands, which indicates the type of urban pollution in the region, which had the greatest impact on the green band and the least impact on the red band. Manuscript profile