相對方位率定
4.3 波段套合成果
圖 10 對比一組 MiniMCA-12 原始影像與經透 視投影轉換波段套合之成果，其中(a)與(b)是原始 影像與透視投影轉換後的假色影像，而(c)與(d)則 是對應的水平與垂直方向的灰階變化剖面圖。以視 覺分析未經任何糾正的原始影像因套合誤差而產 生重影現象，且從水平與垂直剖面圖中亦觀察到各
波段間有嚴重錯開的問題。然而應用本研究提出之 波段套合程序後，圖 10 (b)與(d)顯現了良好的波段 套合成果。另一方面，圖 11 展示一組 MiniMCA-12 波段套合影像，12 個波段以四種不同的 RGB 顏色 組合，亦呈現良好的套合成果。顯示本研究在系統 性修正時雖然僅針對相鄰波段進行特徵匹配，但最 後與其他波段之套合成果仍可達到相當可靠與準 確的成果。
(a)原始影像(2%線性增揚) (R, G, B: 750nm, 570nm, 540nm)
(b)波段套合成果(2%線性增揚) (R, G, B: 750nm, 570nm, 540nm)
(c)原始影像之水平與垂直灰階變化剖面圖 (d)套合影像之水平與垂直灰階變化剖面圖 圖 10 原始影像與波段套合影像之成果比較
(a) (R, G, B: 720 nm, 570 nm, 450 nm) (b) (R, G, B: 750 nm, 650 nm, 510 nm)
(c) (R, G, B: 780 nm, 680 nm, 530 nm) (d) (R, G, B: 950 nm, 700 nm, 550 nm) 圖 11 MiniMCA-12 各波段在不同 RGB 顏色組合下的套合成果
5. 結論
多鏡頭多光譜影像的波段套合在遙測影像分 析前是必須克服的問題，未經修正的影像會造成顯 著的錯位現象，而無法精確分析地物的波譜反射值 以進行後續的精緻農業、地物分類、生物質量監測 等遙測應用。對於本研究採用的 MiniMCA-12 相機
陣列系統，因各鏡頭的透視中心、觀測方向與透鏡 畸變皆不同，會造成顯著的錯位現象，這使得波段 套合在此類攝影系統下更顯得其重要性。本研究根 據其成像幾合特性，提出一波段套合程序，包含系 統性率定、透視投影轉換、特徵點匹配與系統性誤 差修正等步驟，經一系列的改正及量化精度指標與 視覺化分析套合成果，證明能達到 0.2 - 0.55 個像
元的套合精度，足以符合遙感探測各種應用的精度 2008. Speeded-Up Robust Features (SURF).
Computer Vision and Image Understanding, 110:346-359.
Berni, J., Zarco-Tejada, P.J., Suarez, L., and Fereres, E., 2009.Thermal and Narrowband Multispectral Remote Sensing for Vegetation Monitoring From an Unmanned Aerial Vehicle. IEEE Transactions on Geoscience and Remote Sensing, 47:722-738.
Calderón, R., Navas-Cortés, J.A., Lucena, C., and Zarco-Tejada, P.J., 2013. High-resolution airborne hyperspectral and thermal imagery for early detection of Verticillium wilt of olive using fluorescence, temperature and narrow-band spectral indices. Remote Sensing of Environment, 139:231-245.
Cho, W., and Schenk, T., 1992. Resampling Digital Imagery to Epipolar Geometry, IAPRS International Archives of Photogrammetry and Remote Sensing, pp. 404-408.
Dawn, S., Saxena, V., and Sharma, B., 2010. Remote Sensing Image Registration Techniques: A Survey, in: Elmoataz, A., Lezoray, O., Nouboud, F., Mammass, D., Meunier, J. (Eds.), Image and Signal Processing. Springer Berlin Heidelberg, pp. 103-112.
Debella-Gilo, M., and Kääb, A., 2011. Sub-pixel precision image matching for measuring surface displacements on mass movements using normalized cross-correlation. Remote Sensing of Environment, 115:130-142.
Du, Q., Raksuntorn, N., Orduyilmaz, A., and Bruce, L.M., 2008. Automatic Registration and Mosaicking for Airborne Multispectral Image
Sequences. Photogrammetric Engineering &
Remote Sensing, 74:169-181. Rango, A., 2011. Multispectral Remote Sensing from Unmanned Aircraft: Image Processing Workflows and Applications for Rangeland Environments. Remote Sensing, 3:2529-2551.
Lowe, D.G., 2004. Distinctive Image Features from Scale-Invariant Keypoints. International Journal of Computer Vision, 60: 91-110.
Rau, J.Y., and Yeh, P.C., 2012. A Semi-Automatic Image-Based Close Range 3D Modeling Pipeline Using a Multi-Camera Configuration.
Sensors, 12:11271.
Rosten, E., Porter, R., and Drummond, T., 2010.
Faster and better: a machine learning approach to corner detection. IEEE Transactions on Pattern Analysis and Machine Intelligence, 32:
105-119.
Sankaran, S., Maja, J.M., Buchanon, S., and Ehsani, R., 2013. Huanglongbing (citrus greening) detection using visible, near infrared and thermal imaging techniques. Sensors (Basel), 13:2117-2130.
Simper, A., 1996. Correcting general band-to-band misregistrations, Image Processing, 1996.
Proceedings., International Conference, 592:
597-600.
Torres-Sanchez, J., Lopez-Granados, F., De Castro, A.I., and Pena-Barragan, J.M., 2013.
Configuration and specifications of an Unmanned Aerial Vehicle (UAV) for early site specific weed management. PloS one 8, e58210.
Ye, Y., and Shan, J., 2014. A local descriptor based registration method for multispectral remote sensing images with non-linear intensity differences. ISPRS Journal of Photogrammetry and Remote Sensing, 90:83-95.
Zitová, B., and Flusser, J., 2003. Image registration methods: a survey. Image and Vision Computing, 21:977-1000.
1 Ph.D. Student, Department of Geomatics, National Cheng Kung University Received Date: Apr, 14, 2014
2 Associate Professor, Department of Geomatics, National Cheng Kung University Revised Date: Jun. 21, 2016
3 Associate Professor, Department of Geography, National Taiwan University Accepted Date:Aug. 16, 2016
4 Director of Technical Developer, GEOSAT Aerospace Co., Ltd.
5 General Manager, Aeroland UAV Inc.
* Corresponding Author, Phone: 06-2757575 #63812, E-mail: [email protected]