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لیست داوران سال 1401

تهیة نقشة شاخص سطح برگ گیاه نیشکر با استفاده از معکوس‌سازی تصاویر ابرطیفی ماهوارة PRISMA

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری گروه سنجش از دور و GIS، دانشکدة جغرافیا، دانشگاه تهران

2 دانشیار گروه سنجش از دور و GIS، دانشکدة جغرافیا، دانشگاه تهران

3 استاد گروه سنجش از دور و GIS، دانشکدة جغرافیا، دانشگاه تهران

4 پژوهشگر ارشد آزمایشگاه مشاهدات زمینی، آزمایشگاه پردازش تصویر، دانشگاه والنسیا، اسپانیا

چکیده

شاخص سطح برگ نقش مهمی در تبادل ماده و انرژی بین زمین و اتمسفر دارد. مانند سایر گیاهان، شاخص سطح برگ نیشکر معیار خوبی برای وضعیت سلامت و رشد این محصول است که به‌دلیل نقش آن در صنایع غذایی و انرژی، اهمیت اقتصادی بسیاری دارد. ماهوارة PRISMA که در سال 2019 پرتاب شد، یکی از جدیدترین منابع داده‌های ابرطیفی را فراهم کرده است که به‌ویژه، در تهیة نقشة متغیرهای گیاهی کاربرد دارد. در پژوهش حاضر، نوع جدیدی از شبکه‌های عصبی مصنوعی، موسوم به شبکة عصبی تنظیم‌شده با روش بیزین (BRANN) که قانون بیز را برای غلبه بر مشکل بیش‌برازش شبکه‌های عصبی به‌کار می‌برد، استفاده می‌شود. مدل یادشده روی مجموعه‌ای داده، متشکل از طیف دریافت‌شده ازطریق ماهوارة PRISMA به‌منزلة متغیر مستقل و مقادیر اندازه‌گیری شاخص سطح برگ نیشکر به‌منزلة متغیر وابسته، اجرا شد. اندازه‌گیری‌های زمینی شاخص سطح برگ نیشکر در 118 واحد نمونه‌برداری زمینی، روی مزارع کشت‌و‌صنعت نیشکر امیرکبیر در استان خوزستان و در هفت تاریخ متفاوت طی یک دوره رشد نیشکر در سال 1399، انجام شد. مقایسة عملکرد BRANN‌ با یک روش متعارف شبکة عصبی، یعنی شبکة آموزش‌دیده با روش لونبرگ‌ـ مارکوارت (LMANN) در بازیابی شاخص سطح برگ نیشکر از طیف PRISMA، حاکی از این است کهRMSE  بازیابی از 26/2 (m2/m2) به‌روش LMANN به 67/0 (m2/m2)، با استفاده از روش BRANN کاهش یافته است. در این پژوهش، به‌منظور کاهش ابعاد داده نیز از تبدیل مؤلفه‌های اصلی استفاده شد. در بازیابی شاخص سطح برگ از بیست مؤلفة‌ اصلی اول نیز RMSE از 41/1 (m2/m2) با استفاده از روش LMANN به 71/0 (m2/m2) طبق روش BRANN کاهش یافت. استفاده از مؤلفه‌های اصلی باعث کاهش چشمگیر زمان محاسباتی شد. با اجرای مدل آموزش‌دیدة BRANN‌ روی تصاویر PRISMA به‌صورت پیکسل‌به‌پیکسل، نقشة شاخص سطح برگ نیشکر تولید شد. ارزیابی این نقشه نشان داد که این نقشه تغییرات مکانی شاخص سطح برگ نیشکر را به‌خوبی نشان می‌دهد. نتایج این تحقیق بیانگر قابلیت بالای روش BRANN‌ و تصاویر PRISMA برای بازیابی شاخص سطح برگ نیشکر است.

کلیدواژه‌ها

عنوان مقاله [English]

Mapping Sugarcane Leaf Area Index by Inverting PRISMA Hyperspectral Images

نویسندگان [English]

  • Mohammad Hajeb 1
  • Saeid Hamzeh 2
  • Seyed Kazem Alavipanah 3
  • Jochem Verrelst 4

1 P.hd. Student, Dep. of Remote Sensing and GIS, Faculty of Geography, University of Tehran, Tehran

2 Associate Prof., Dep. of Remote Sensing and GIS, Faculty of Geography, University of Tehran, Tehran

3 Prof. of Dep. of Remote Sensing and GIS, Faculty of Geography, University of Tehran, Tehran

4 Image Processing Laboratory (IPL), Parc Científic, Universitat de Val`encia, Val`encia, Spain

چکیده [English]

Leaf Area Index (LAI) plays a critical role in the mass and energy exchanges between the earth and the atmosphere. Like of other plants, LAI of sugarcane is a good indicator of the health status and growth of this crop which is of great economic importance due to its role in the food and energy industries. Launched in 2019, the PRISMA satellite provides one of the most recent hyperspectral data sources which are applicable especially for mapping plant variables. In this study, a new kind of Artificial Neural Networks (ANN) so-called Bayesian Regularized Artificial Neural Networkk (BRANN) which applies Bayes' theorem to overcome the overfitting problem of neural networks is used. The model was implemented on a data set consisting of spectrum obtained by PRISMA satellite as an independent variable and sugarcane LAI measurements as a dependent variable. The ground measurements of sugarcane LAI were carried out in 118 elementary sampling units on the fields of Amir Kabir sugarcane cultivation and industry in Khuzestan province and on seven different dates during a sugarcane growth period in 2020. Comparing the performance of BRANN in retrieving sugarcane LAI from PRISMA spectra with that of a conventional ANN trained with the Levenberg-Marquardt algorithm (LMANN) indicates that the retrieval RMSE is reduced from 2.26 m2/m2 applying LMANN to 0.67 m2/m2 applying the BRANN method. In this study, the principle component analysis was also used dimensionality reduction. Retrieving LAI from the first 20  principle components, RMSE was also reduced from 1.41 m2/m2 applying LMANN to 0.71 m2/m2 applying BRANN. Exploiting principal components significantly reduced computational time. By implementing the calibrated BRANN model over the PRISMA image pixel by pixel, the sugarcane LAI map was generated. Evaluating this map showed that this map represents the spatial variations of sugarcane LAI well. The results of this study indicate the high performance of the BRANN method and high potential of PRISMA images to retrieve sugarcane LAI.

کلیدواژه‌ها [English]

  • Vegetation parameter retrieval
  • Leaf Area Index
  • Artificial Neural Networks
  • Inverting
  • Hyperspectral Remote Sensing
  • Sugarcane
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نشریه سنجش از دور و GIS ایران
دوره 15، شماره 1 - شماره پیاپی 57
فروردین 1402
صفحه 85-108
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