نتایج جستجو برای: dem

تعداد نتایج: 20781  

2008
Zhengxiao Li James Bethel

To generate an accurate digital elevation model (DEM), Interferometric Synthetic Aperture Radar (InSAR) requires precise orbit data and baseline information, which are not always available. An alternative approach is to apply quality ground control points (GCPs) into the InSAR processing. However, locating high quality GCPs can also be difficult task, due to the low spatial resolution and radio...

Journal: :Trans. GIS 1997
Marilyn O. Ruiz

Users of GIS are faced with the ongoing and difficult problem of estimating the validity of a GIS output given the uncertainty of the quality of cLgital mapped data. This research project examines the manner in which error from a digital elevation model (DEM) results in error in an estimate of a viewshed. The data set includes two DEMs for the same study area. A 10-metre DEM serves as the contr...

2008
Manoj Karkee Brian L. Steward Samsuzana Abd Aziz

* Corresponding author. E-mail address: [email protected] (B. 1537-5110/$ – see front matter a 2008 IAgrE doi:10.1016/j.biosystemseng.2008.09.010 Digital Elevation Model (DEM) fusion was investigated for improving the overall accuracy of DEMs. The approach was applied to two public domain products: Shuttle Radar Topographic Mission (SRTM) DEM and Advanced Spaceborne Thermal Emission and Refl...

جمشیدزاده, ابوالفضل, خزائی, صفا, عارفی, حسین, علیزاده نائینی, امین,

یکی از راهکارهای اساسی در تولید و به‌روزرسانی داده­های مکانی از جمله مدل­های رقومی ارتفاعی (DEM) استفاده از تصاویر پوششی ماهواره‌ای است. برای این منظور، معمولاً از ضرایب چندجمله‌ای‌های کسری (RPC ها) که به‌عنوان یک فراداده‌ی اصلی در کنار تصاویر ماهواره‌ای قرار دارند استفاده می‌شود. با این ‌وجود، استفاده از این ضرایب به دلیل یکسری خطاهای سامانمند که در جمع‌آوری آن‌ها وجود دارد منجر به تولید DEM خط...

اردوان کمالی شهلا محمودی فریدون سرمدیان

مدل رقومی ارتفاع(DEM) امروزه به عنوان ابزار موثری در مطالعات کمی زیست محیطی و مدیریت منابع اراضی برای استخراج داده های ارتفاعی به کار می رود. پیشرفت و توسعه سنجنده ها و ماهواره های منابع زمینی امکان تولید DEM از تصاویر ماهواره ای را فراهم کرده است. DEM های تولید شده از داده های مذکورنه تنها در تفسیر های دو بعدی بلکه در مطالعات سه بعدی سطح زمین نیز بکار برده می شوند. تصاویر سنجنده ASTER که یکی ...

2005
S. DINESH P. RADHAKRISHNAN

One of the biggest problems faced while analyzing digital elevation models (DEMs), particularly DEMs that are produced using photogrammetry, is to avoid pits and peaks in DEMs. Peaks and pits, which are errors, are generated during the surface generation process. DEM smoothening is an important preprocessing step meant for removing these errors. This paper discusses two linear DEM smoothening m...

اسدزاده, فرخ, میرزایی, سلمان,

Topographic factor is an important factor of computer models of USLE family due to the high sensitivity of model results to its variation and complicated effects of topography on soil erosion. Moore and Wilson (1992) have introduced a well-known method to compute LS factor of RUSLE model using digital elevation model (DEM).The objective of this study was to determine the proper cell size of DEM...

1999
M. L. Mittal V. K. Singh

Very little work has been done on the systematic evaluation of effect of compression on the accuracy of DEM derived using satellites imageries. Most of studies have been carried out for aerial images and models have been developed which relate DEM accuracy with compression. One such model predicts effect of compression on DEM accuracy as 0.2% of flight height for CR up to 15:1 but these models ...

Journal: :تحقیقات آب و خاک ایران 0
اردوان کمالی فریدون سرمدیان شهلا محمودی

digital elevation model (dem) is increasingly used these days as an effective tool to extract elevation data in quantitative environmental and land management studies. the improvement of sensors and land resource satellites has made it possible to generate dem from remotely sensed data. dems which are produced from these data are applied not only in the two dimensional (2d) but also in the thre...

Journal: :International psychogeriatrics 2015
Lisa D Van Mierlo Franka J M Meiland Peter M Van de Ven Hein P J Van Hout Rose-Marie Dröes

BACKGROUND Few personalized e-interventions are available for informal and professional caregivers of people with dementia. The DEMentia Digital Interactive Social Chart (DEM-DISC) is an ICT tool to support customized disease management in dementia. The aim of this study was to improve and evaluate DEM-DISC, its user-friendliness and usefulness and to investigate the future implementation. ME...

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