Scientific- Research Quarterly of Geographical Data (SEPEHR)

Scientific- Research Quarterly of Geographical Data (SEPEHR)

Accuracy assessment of Digital Elevation Models (DEM) of SRTM and ASTER satellites with precise ground observations (DGPS) Case study: from the Azad dam to the plain of Ghorveh-Dehgolan, Sanandaj

Document Type : Research Paper

Authors
Mostafa Khabazi 1
Ali Mehrabi 1
Javad Arabi 2
1 Assistant Professor, Shahid Bahonar University, Kerman, Iran
2 Msc student, remote sensing and GIS department, Islamic Azad University of Larestan
10.22131/sepehr.2019.37515
Abstract
Extended Abstract
Introduction
Digital elevation model (DEM) is the raster representation of the ground surface so that the information of each cell on the image has a value equal to the altitude from the sea level corresponding to the same spot on the ground. DEM is an appropriate tool for the generation of topographic maps and contour lines, access to the information of surface roughness, three dimensional vision, etc. (Jacobsen, 2004). The accuracy of the digital elevation model is effective on the accuracy of the information from which it is obtained. This is why researchers are always looking for a way to increase the accuracy of digital elevation models. Among the information resources that are used to generate this model are ground mapping, aerial photography, satellite images, radar data, and Lidar. Some of these data generate the digital elevation model with little accuracy due to the insufficiency of the elevation information. The aim of this paper is to investigate the accuracy of DEMs derived from ASTER satellite images and SRTM data with 30 and 90-meter pixel dimensions and the digital elevation model derived from the topographic 1:25000-scale maps with Differential Global Positioning System (DGPS) in different landforms including plains, hills and mountains.
 
Materials and Methods
The study area is a part of the project of dam and water transfer system from the Azad dam to the plain of Ghorve-Dehgolan (with the goal of transferring water from the catchments of Sirvan River into the country) in the province of Kurdistan and the city of Sanandaj. In this study, the Real-Time kinematic method (RTK) was used to locate the points. In this method, assuming that the coordinates of the reference station are known and comparing it with the location obtained from the GPS receiver, a correction value is obtained that is applied to the coordinates obtained for the Rover Station, which is known as the relative or differential method. In this method, the corrections are calculated asreal-time during the observations and are considered in the determination of the Rover location.The Leica GS10 GNSS receivers were used in this study. First, two reference stations were determined using the Fast Static method and then, the Real-Time kinematic (RTK) method was used. In order to investigate the extent of the data compliance and relation, the Pearson linear correlation analysis was used and the accuracy assessment of the extracted digital elevation models was carried out using the RMSE, mean error and standard deviation.
 
Results & Discussion
The statistical parameters such as root mean square error (RMSE), bias (µ) and standard deviation () were used to assess the accuracy of each one of the investigated digital models. By comparing different sources that create DEMs, it can be seen that the minimum error is first related to the digital elevation model extracted from the contour lines of the 1:25000-scale map (27/6 = RMSE) and then to the ASTER digital elevation model with the pixel size of 30 meters (RMSE=7.43). The 30-meter pixel size DEM has always led to better results than the 90- meter pixel size DEM. Based on the mean error standard, the minimum bias is related to ASTER30 m (bias of 2 m) and then to the 1: 25,000 DEM (2.17). The maximum bias was related to 30-and 90-meter models extracted from the SRTM data. The results of standard deviation error were in compliance with the RMSE results, which confirmed the superiority of 1:25000-scale map and ASTER30 m DEMs. The results showed that the determination coefficient of relationship between the ground data and digital elevation models is between 97 and 99. The maximum compliance is related to the digital elevation model extracted from the 1:25000-scale topographic data and the ASTER30 m DEM, while the minimum compliance is related to the SRTM90 m data. In general, the compliance of the digital elevation models with the ground data decreased as the field's conditions became more difficult, i.e. from plain to mountain.
 
Conclusion
The results of DEMs accuracy assessment showed that the minimum error was primarily related to 1:25000 contour lines DEM (RMSE=6.27) and then, to the ASTER30 m DEM (RMSE=7.43). The pixel size of 30 meters has always been better than the pixels size of 90 meters. Based on the mean error standard, the minimum bias is related to the ASTER 30 m (bias of 2 m) and then, to the 1: 25,000 DEM (2.17). The maximum bias was related to 30-and 90-meter models extracted from the SRTM data. The results of the standard deviation error were consistent with the RMSE results, which confirmed the superiority of the digital elevation models extracted from the topographic 1:25000-scale maps and the ASTER30 m DEM.
Keywords
Accuracy assessment
DEM
ASTER
SRTM
DGPS
1. آقا طاهر، صمدی، لعلی نیت، نجفی؛ رضا، مهدی، ایلیا، ایمان؛ 1395؛ ارزیابی مقایسه ای صحت ارتفاعی مدل‌های رقومی ارتفاعی ASTER و SRTM، فصلنامه علمی پژوهشی اطلاعات جغرافیایی (سپهر)، دوره 25، شماره 99، صص103 - 113.
2. اشرفی، علیمی؛ علی، محمد امیر؛ 1393؛ مقایسه روش‌های مختلف تهیه مدل ارتفاع رقومی مورد شناسی: حوضه آبخیز نوفرست، شهرستان بیرجند، استان خراسان جنوبی، جغرافیا و آمایش شهری - منطقه‌ای، دوره4، شماره  14،  صص 119 -140.
3. حسین‌زاده، نداف سنگانی؛ سیدرضا، مهوش؛ 1392؛ ارزیابی دقّت مدل‌های رقومی ارتفاع (DEMs) حاصل از نقشه‌های توپوگرافی و مقایسه‎ی تطبیقی آن با DEM‌های ماهواره‌ای (مطالعه‎ی موردی: DEMهای توپوگرافی و ASTER منطقه‎ی آبغه در خراسان رضوی، مجله پژوهش‌های جغرافیای طبیعی، دوره 45، شماره 1، صص71 -86.
4. حسین‌زاده، جهادی؛ سید رضا، مهناز؛ 1389؛ ارزیابی دقّت مدل‌های رقومی ارتفاع (DEMs) و الگوریتم‌های GIS  در تحلیل‌های مورفومتری رودخانه‌ای (نمونة مورد مطالعه : حوضة آبریز رباط قره بیل در خراسان شمالی)، جغرافیا و توسعة ناحیه‌ای، دوره 17، شمارة  14، صص 66 - 76.
5. عزیزیان، شکوهی؛ اصغر؛ علیرضا؛ 1393؛ بررسی اثر روش‌های مختلف ساخت مدل‌های رقومی ارتفاعی بر عملکرد مدل نیمه توزیعی TOPMODEL، تحقیقات منابع آب و خاک ایران، سال دهم، شماره 1، صص 111-116.
6. فیضی‌زاده، عبدلله آبادی، ولی‌زاده؛ بختیار، سلیمه، خلیل؛ 1395؛ مدلسازی عدم قطعیت حاصل از داده‌های ارتفاعی SRTM و ASTER و تأثیر آن بر طبقه بندی لندفرم ها در حوضه ی آبریز گرم چای. فصلنامه علمی پژوهشی اطلاعات جغرافیایی (سپهر)، دوره 26، شماره 103، صص29 - 41.
7. مروج، دلاور، صادق بیگی؛ کامران، محمد امیر، اکرم؛ 1394؛ عنوان اهمیت انتخاب مدل رقومی ارتفاعی مناسب در مدیریت و حفاظت منابع خاک و آب (مطالعه موردی: سد تهم، استان زنجان)، تحقیقات کاربردی خاک، جلد 3، شماره 2، صص 42 -54.
8. Alganci, U., Besol, B., Sertel, E., (2018). Accuracy Assessment of Different Digital Surface Models, International Journal of Geo-Information 7(114): 1-16.
9. Ashourloo, D., (2007). An Evaluation of Hydrological Pit Filling Methods in the Ekbatan Watersheds. Environmental sciences 4(3): 49-60.
10. Chaieb A., Rebai, N., Bouaziz, S., 2016, Vertical Accuracy Assessment of SRTM Ver 4.1 and ASTER GDEM Ver 2 Using GPS Measurements in Central West of Tunisia, Earth & Environmental Sciences, 8(1): 231-252.
11. Ebaid, H., 2014, Accuracy Enhancement of SRTM and ASTER Dems Using Weight Estimation Regression Model. International Journal of Research in Engineering and Technology, 3(8): 1231-1244.
12. Jacobsen, K., 2004- DEM Generated by SPOT HRS. ISPRS Congress, Istanbul, 20: 439-444.
13. Jing L., (2005). Accuracy and reliability of map-matched GPS coordinates the dependence on terrain model resolution and interpolation algorithm. Computers&Geosciences 31: 241–251.
14. Lin, Z. and Oguchi, T., (2006). DEM Analysis on Longitudinal and Transverse Profile of Steep Mountainous Watersheds. Geomorphology 78: 125- 135.
15. Sandip M., 2013- Evaluation of vertical accuracy of open source Digital Elevation Model (DEM). International Journal of Applied Earth Observation and Geoinformation 21(2): 205–217.
16. Sefercik.U.G. (2012). Performance Estimation of Aster Global DEM Depending upon the Terrain Inclination, J Indian Society of Remote Sensing (December 2012) 40(4):565–576.
17. Stage, F., Bonnet, M., Timouk, F., Garnier, J., 2015, Accuracy assessment of SRTM v4 and ASTER GDEM v2 over the Altiplano watershed using ICESat/GLAS data, International Journal of Remote Sensing 36(2): 541-562.
18. Thompson, J., Bell, J. and Butler, C., (2001). Digital elevation model resolution: effects on terrain attribute calculation and quantitative soillandscape modeling. Geoderma 100: 67–89.
19. Zevenbergen, L. W. and Thorne, C. R., (1987). Quantitative Analysis of land surface topography. Earth surface processes and landforms, 12: 45 – 56.
20. Zhang, W.H. and Montgomery, D.R., (1994). Digital elevation model grid size, landscape representation & hydrologic simulations. Water Resources Research 30:1019-1028.