{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:39:21Z","timestamp":1760150361998,"version":"build-2065373602"},"reference-count":52,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2023,10,30]],"date-time":"2023-10-30T00:00:00Z","timestamp":1698624000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Municipal Government of Quzhou","award":["2023D041","2023D026"],"award-info":[{"award-number":["2023D041","2023D026"]}]},{"name":"China Scholarship Council","award":["2023D041","2023D026"],"award-info":[{"award-number":["2023D041","2023D026"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Multistatic airborne SAR (MuA-SAR) benefits from the ability to flexibly adjust the positions of multiple transmitters and receivers in space, which can shorten the synthetic aperture time to achieve the required resolution. To ensure both imaging efficiency and quality of different system spatial configurations and trajectories, the fast factorized back projection (FFBP) algorithm is proposed. However, if the FFBP algorithm based on polar coordinates is directly applied to the MuA-SAR system, the interpolation in the recursive fusion process will bring the problem of redundant calculations and error accumulation, leading to a sharp decrease in imaging efficiency and quality. In this paper, a unified Cartesian fast factorized back projection (UCFFBP) algorithm with a multi-level regional attention strategy is proposed for MuA-SAR fast imaging. First, a global Cartesian coordinate system (GCCS) is established. Through designing the rotation mapping matrix and phase compensation factor, data from different bistatic radar pairs can be processed coherently and efficiently. In addition, a multi-level regional attention strategy based on maximally stable extremal regions (MSER) is proposed. In the recursive fusion process, only the suspected target regions are paid more attention and segmented for coherent fusion at each fusion level, which further improves efficiency. The proposed UCFFBP algorithm ensures both the quality and efficiency of MuA-SAR imaging. Simulation experiments verified the effectiveness of the proposed algorithm.<\/jats:p>","DOI":"10.3390\/rs15215183","type":"journal-article","created":{"date-parts":[[2023,10,30]],"date-time":"2023-10-30T13:20:07Z","timestamp":1698672007000},"page":"5183","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["MuA-SAR Fast Imaging Based on UCFFBP Algorithm with Multi-Level Regional Attention Strategy"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5692-4366","authenticated-orcid":false,"given":"Fanyun","family":"Xu","sequence":"first","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rufei","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yulin","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"},{"name":"Yangtze Delta Region Institute, University of Electronic Science and Technology of China (UESTC), Quzhou 324003, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7408-1654","authenticated-orcid":false,"given":"Deqing","family":"Mao","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianyu","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yongchao","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"},{"name":"Yangtze Delta Region Institute, University of Electronic Science and Technology of China (UESTC), Quzhou 324003, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6761-2269","authenticated-orcid":false,"given":"Yin","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Gao, F., Yang, Y., Wang, J., Sun, J., Yang, E., and Zhou, H. (2018). A deep convolutional generative adversarial networks (DCGANs)-based semi-supervised method for object recognition in synthetic aperture radar (SAR) images. Remote Sens., 10.","DOI":"10.3390\/rs10060846"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3365","DOI":"10.1109\/TAES.2019.2906414","article-title":"Deception against near-field synthetic aperture radar using networked jammers","volume":"55","author":"Zhou","year":"2019","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1946","DOI":"10.1016\/j.cja.2019.03.021","article-title":"A novel visual attention method for target detection from SAR images","volume":"32","author":"Fei","year":"2019","journal-title":"Chin. J. Aeronaut."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"109156","DOI":"10.1016\/j.sigpro.2023.109156","article-title":"Synthetic Aperture Radar Image and its Despeckling using Variational Methods: A Review of Recent Trends","volume":"212","author":"Baraha","year":"2023","journal-title":"Signal Process."},{"key":"ref_5","first-page":"108","article-title":"Digital processing of synthetic aperture radar data","volume":"1","author":"Cumming","year":"2005","journal-title":"Artech House"},{"key":"ref_6","first-page":"105","article-title":"High resolution radar real-time signal and information processing","volume":"16","author":"Long","year":"2019","journal-title":"China Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"6914","DOI":"10.1109\/TGRS.2020.2977731","article-title":"High-resolution forward-looking multichannel SAR imagery with array deviation angle calibration","volume":"58","author":"Lu","year":"2020","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","unstructured":"Wu, J., Yang, J., Huang, Y., Yang, H., and Wang, H. (2009, January 4\u20138). Bistatic forward-looking SAR: Theory and challenges. Proceedings of the 2009 IEEE Radar Conference, Pasadena, CA, USA."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/LGRS.2023.3330882","article-title":"A Super-Resolution Scheme for Multichannel Radar Forward-Looking Imaging Considering Failure Channels and Motion Error","volume":"20","author":"Chen","year":"2023","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"8033","DOI":"10.1109\/JSTARS.2021.3103802","article-title":"Forward-looking geometric configuration optimization design for spaceborne-airborne multistatic synthetic aperture radar","volume":"14","author":"Mao","year":"2021","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1109\/LGRS.2014.2337054","article-title":"Point spread function analysis for GNSS-based multistatic SAR","volume":"12","author":"Santi","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1049\/ip-rsn:20045111","article-title":"Spaceborne bi-and multistatic SAR: Potential and challenges","volume":"153","author":"Krieger","year":"2006","journal-title":"IEE Proc.-Radar Sonar Navig."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Krieger, G., Zonno, M., Rodriguez-Cassola, M., Lopez-Dekker, P., Mittermayer, J., Younis, M., Huber, S., Villano, M., De Almeida, F.Q., and Prats-Iraola, P. (2017, January 23\u201328). MirrorSAR: A fractionated space radar for bistatic, multistatic and high-resolution wide-swath SAR imaging. Proceedings of the 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Fort Worth, TX, USA.","DOI":"10.1109\/IGARSS.2017.8126916"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3487","DOI":"10.1109\/TGRS.2011.2115250","article-title":"Spatial resolution of bistatic synthetic aperture radar: Impact of acquisition geometry on imaging performance","volume":"49","author":"Moccia","year":"2011","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8522","DOI":"10.1109\/JSTARS.2021.3106449","article-title":"Heuristic path planning method for multistatic UAV-borne SAR imaging system","volume":"14","author":"Xu","year":"2021","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1080\/01431169108929650","article-title":"A new approach to range-Doppler SAR processing","volume":"12","author":"Smith","year":"1991","journal-title":"Int. J. Remote Sens."},{"key":"ref_17","unstructured":"Hughes, W., Gault, K., and Princz, G. (1996, January 31). A comparison of the Range-Doppler and Chirp Scaling algorithms with reference to RADARSAT. Proceedings of the IGARSS\u201996, 1996 International Geoscience and Remote Sensing Symposium, Lincoln, NE, USA."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"294","DOI":"10.1109\/TGRS.2019.2936255","article-title":"Focusing the L-band spaceborne bistatic SAR mission data using a modified RD algorithm","volume":"58","author":"Li","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1147","DOI":"10.1109\/TAES.2004.1386870","article-title":"Polar format algorithm for bistatic SAR","volume":"40","author":"Rigling","year":"2004","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"323","DOI":"10.2528\/PIER10030703","article-title":"Polar Format Algorithm for Spotlight Bistatic Sar with Arbitrary Geometry Configuration","volume":"103","author":"Sun","year":"2010","journal-title":"Prog. Electromagn. Res."},{"key":"ref_21","unstructured":"Cumming, I.G., Neo, Y.L., and Wong, F.H. (2003, January 21\u201325). Interpretations of the omega-K algorithm and comparisons with other algorithms. Proceedings of the IGARSS 2003 IEEE International Geoscience and Remote Sensing Symposium (IEEE Cat. No. 03CH37477), Toulouse, France."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2899","DOI":"10.1109\/TGRS.2009.2017522","article-title":"Bistatic SAR data focusing using an omega-K algorithm based on method of series reversion","volume":"47","author":"Liu","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1747","DOI":"10.1109\/LGRS.2016.2602442","article-title":"Frequency-domain imaging algorithm for single-input\u2013multiple-output array","volume":"13","author":"Zhu","year":"2016","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_24","unstructured":"Gaibel, A., and Boag, A. (2016, January 5\u20137). Back-projection SAR imaging using FFT. Proceedings of the 2016 European Radar Conference (EuRAD), London, UK."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Zeng, D., Zeng, T., Hu, C., and Long, T. (2006, January 16\u201319). Back-projection algorithm characteristic analysis in forward-looking bistatic SAR. Proceedings of the 2006 CIE International Conference on Radar, Shanghai, China.","DOI":"10.1109\/ICR.2006.343181"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"McCorkle (1991, January 1\u20133). Focusing of synthetic aperture ultra wideband data. Proceedings of the IEEE 1991 International Conference on Systems Engineering, Dayton, OH, USA.","DOI":"10.1109\/ICSYSE.1991.161068"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Yang, Y., Pi, Y., and Li, R. (2006, January 16\u201319). Back projection algorithm for spotlight bistatic SAR imaging. Proceedings of the 2006 CIE International Conference on Radar, Shanghai, China.","DOI":"10.1109\/ICR.2006.343581"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2724","DOI":"10.1109\/TAES.2018.2828238","article-title":"An extended fast factorized back projection algorithm for missile-borne bistatic forward-looking SAR imaging","volume":"54","author":"Feng","year":"2018","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_29","unstructured":"Xiao, S., Munson, D.C., Basu, S., and Bresler, Y. (November, January 29). An N 2 logN back-projection algorithm for SAR image formation. Proceedings of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No. 00CH37154), Pacific Grove, CA, USA."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"McCorkle, J.W., and Rofheart, M. (1996, January 8\u20139). Order N^2 log (N) backprojector algorithm for focusing wide-angle wide-bandwidth arbitrary-motion synthetic aperture radar. Proceedings of the Radar Sensor Technology, Orlando, FL, USA.","DOI":"10.1117\/12.243085"},{"key":"ref_31","unstructured":"Yegulalp, A.F. (1999, January 22). Fast backprojection algorithm for synthetic aperture radar. Proceedings of the 1999 IEEE Radar Conference, Radar into the Next Millennium (Cat. No. 99CH36249), Waltham, MA, USA."},{"key":"ref_32","unstructured":"Ding, Y., and Munson, D.J. (2002, January 22\u201325). A fast back-projection algorithm for bistatic SAR imaging. Proceedings of the International Conference on Image Processing, Rochester, NY, USA."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"760","DOI":"10.1109\/TAES.2003.1238734","article-title":"Synthetic-aperture radar processing using fast factorized back-projection","volume":"39","author":"Ulander","year":"2003","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_34","first-page":"1","article-title":"An Efficient Algorithm Based on Frequency Scaling for THz Stepped-Frequency SAR Imaging","volume":"60","author":"Wang","year":"2022","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_35","unstructured":"Ulander, L.M., Froelind, P.O., Gustavsson, A., Murdin, D., and Stenstroem, G. (2010, January 7\u201310). Fast factorized back-projection for bistatic SAR processing. Proceedings of the 8th European Conference on Synthetic Aperture Radar, VDE, Aachen, Germany."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1508","DOI":"10.1109\/JSTARS.2019.2907138","article-title":"A new fast factorized back projection algorithm for bistatic forward-looking SAR imaging based on orthogonal elliptical polar coordinate","volume":"12","author":"Zhou","year":"2019","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1460","DOI":"10.1109\/LGRS.2013.2295326","article-title":"A fast BP algorithm with wavenumber spectrum fusion for high-resolution spotlight SAR imaging","volume":"11","author":"Zhang","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Sun, H., Sun, Z., Chen, T., Miao, Y., Wu, J., and Yang, J. (2022). An Efficient Backprojection Algorithm Based on Wavenumber-Domain Spectral Splicing for Monostatic and Bistatic SAR Configurations. Remote Sens., 14.","DOI":"10.3390\/rs14081885"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Guo, Y., Suo, Z., Jiang, P., and Li, H. (2021). A Fast Back-Projection SAR Imaging Algorithm Based on Wavenumber Spectrum Fusion for High Maneuvering Platforms. Remote Sens., 13.","DOI":"10.3390\/rs13091649"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Dong, Q., Yang, Z., Sun, G., and Xing, M. (2016, January 10\u201315). Cartesian factorized backprojection algorithm for synthetic aperture radar. Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Beijing, China.","DOI":"10.1109\/IGARSS.2016.7729272"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1160","DOI":"10.1109\/JSEN.2017.2780164","article-title":"Cartesian factorized backprojection algorithm for high-resolution spotlight SAR imaging","volume":"18","author":"Dong","year":"2017","journal-title":"IEEE Sens. J."},{"key":"ref_42","first-page":"1","article-title":"A novel CFFBP algorithm with noninterpolation image merging for bistatic forward-looking SAR focusing","volume":"60","author":"Li","year":"2022","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_43","first-page":"1","article-title":"Spatial Configuration Design for Multistatic Airborne SAR Based on Multiple Objective Particle Swarm Optimization","volume":"61","author":"Xu","year":"2023","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1109\/TAES.2005.1468741","article-title":"Generalized approach to resolution analysis in BSAR","volume":"41","author":"Zeng","year":"2005","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1584","DOI":"10.1109\/TAES.2018.2873076","article-title":"Bistatic SAR: Forecasting spatial resolution","volume":"55","author":"Dower","year":"2018","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"761","DOI":"10.1016\/j.imavis.2004.02.006","article-title":"Robust wide-baseline stereo from maximally stable extremal regions","volume":"22","author":"Matas","year":"2004","journal-title":"Image Vis. Comput."},{"key":"ref_47","unstructured":"Donoser, M., and Bischof, H. (2006, January 17\u201322). Efficient maximally stable extremal region (MSER) tracking. Proceedings of the 2006 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR\u201906), New York, NY, USA."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Wang, R., Xu, F., Pei, J., Wang, C., Huang, Y., Yang, J., and Wu, J. (August, January 28). An improved faster R-CNN based on MSER decision criterion for SAR image ship detection in harbor. Proceedings of the IGARSS 2019 IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan.","DOI":"10.1109\/IGARSS.2019.8898078"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"6940","DOI":"10.1109\/TGRS.2016.2592536","article-title":"Motion errors and compensation for bistatic forward-looking SAR with cubic-order processing","volume":"54","author":"Pu","year":"2016","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1040","DOI":"10.1109\/TAES.2009.5259181","article-title":"GPS-based time & phase synchronization processing for distributed SAR","volume":"45","author":"Wang","year":"2009","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"424","DOI":"10.1109\/LGRS.2006.874164","article-title":"Impact of oscillator noise in bistatic and multistatic SAR","volume":"3","author":"Krieger","year":"2006","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1109\/83.552098","article-title":"Attributed scattering centers for SAR ATR","volume":"6","author":"Potter","year":"1997","journal-title":"IEEE Trans. Image Process."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/21\/5183\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:14:30Z","timestamp":1760130870000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/21\/5183"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,30]]},"references-count":52,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2023,11]]}},"alternative-id":["rs15215183"],"URL":"https:\/\/doi.org\/10.3390\/rs15215183","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2023,10,30]]}}}