Observation Mode and Region Segmentation of New Generation Geostationary Meteorological Satellite of China

Three-axis stabilized Fengyun-4 （FY-4） satellite scries is the new generation of geostationary meteorological satellite in China. The ob-servation flexibility brought by three-axis stabilization makes it possible to design different observation modes for different targets. Important observation modes of the Advanced Geosynchronous Radiation Imager （AGRI）, the core instrument onboard FY-4A, are presented, from the earth obser- vation, navigation and calibration perspective. As the time consumed in full disk and hemisphere observations exceed the time limitation, different region segmentation methods are proposed. Results show the methods are effective, and the full disk as well as hemisphere observations can both be accomplished in the given time. Finally the three-region segmentation method and two-region segmentation method are chosen for full disk and hemisphere observations, respectively, in view of the observation instructions＇ complexity as well as the time consuming. The research results paved the way for the core instrument＇s daily operation, and have been used in FY-4A in-orbit test.

Visual navigation in orchard based on multiple images at different shooting angles

The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve autonomous navigation in orchard,a visual navigation method based on multiple images at different shooting angles is proposed in this paper.A dynamic image capturing device is designed for camera installation and multiple images can be shot at different angles.Firstly,the obtained orchard images are classified into sky and soil detection stage.Each image is transformed to HSV space and initially segmented into sky,canopy and soil regions by median filtering and morphological processing.Secondly,the sky and soil regions are extracted by the maximum connected region algorithm,and the region edges are detected and filtered by the Canny operator.Thirdly,the navigation line in the current frame is extracted by fitting the region coordinate points.Then the dynamic weighted filtering algorithm is used to extract the navigation line for the soil and sky detection stage,respectively,and the navigation line for the sky detection stage is mirrored to the soil region.Finally,the Kalman filter algorithm is used to fuse and extract the final navigation path.The test results on 200 images show that the accuracy of visual navigation path fitting is 95.5%,and single frame image processing costs 60 ms,which meets the real-time and robustness requirements of navigation.The visual navigation experiments in Camellia oleifera orchard show that when the driving speed is 0.6 m/s,the maximum tracking offset of visual navigation in weed-free and weedy environments is 0.14 m and 0.24 m,respectively,and the RMSE is 30 mm and 55 mm,respectively.

A framework of region-based dynamic image fusion

A new framework of region-based dynamic image fusion is proposed. First, the technique of target detection is applied to dynamic images (image sequences) to segment images into different targets and background regions. Then different fusion rules are employed in different regions so that the target information is preserved as much as possible. In addition, steerable non-separable wavelet frame transform is used in the process of multi-resolution analysis, so the system achieves favorable characters of orientation and invariant shift. Compared with other image fusion methods, experimental results showed that the proposed method has better capabilities of target recognition and preserves clear background information.

Fusion of Infrared and Visible Light Images Based on Region Segmentation

This article proposes a novel method to fuse infrared and visible light images based on region segmentation. Region segmen-tation is used to determine important regions and background information in the input image. The non-subsampled contourlet transform (NSCT) provides a flexible multiresolution,local and directional image expansion,and also a sparse representation for two-dimensional (2-D) piecewise smooth signal building images,and then different fusion rules are applied to fuse the NSCT coefficients fo...

A region segmentation based algorithm for building a crystal position lookup table in a scintillation detector

In a scintillation detector, scintillation crystals are typically made into a 2-dimensional modular array. The location of incident gamma-ray needs be calibrated due to spatial response nonlinearity. Generally, position histograms--the characteristic flood response of scintillation detectors are used for position calibration. In this paper, a position calibration method based on a crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed. Firstly, the position histogram is preprocessed, such as noise reduction and image enhancement. Then the processed position histogram is segmented into disconnected regions, and crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and the crystal position lookup table is generated. The scheme is evaluated by the whole-body positron emission tomography （PET） scanner and breast dedicated single photon emission computed tomography scanner developed by the Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and applicable to any configurations of scintillation detector.

Changes in retinal capillary density in female with type 2 diabetes and gestational diabetes——an analysis based on OCTA technology

AIM:To evaluate alterations in conjunctival vascular density(CVD)and macular capillary density(MCD)in female patients with type 2 diabetes mellitus(T2DM)and gestational diabetes mellitus(GDM)using optical coherence tomography angiography(OCTA).METHODS:A total of 60 female participants were recruited,comprising 20 patients with T2DM,20 patients with GDM,and 20 healthy age-matched controls(HCs).OCTA was used to assess superficial and deep retinal and conjunctival capillary plexuses.Subsequently,changes in MCD were analyzed using a circular segmentation method(C1-C6),a hemispheric quadrant segmentation method[superior right(SR),superior left(SL),inferior left(IL),and inferior right(IR)],and the early treatment diabetic retinopathy study(ETDRS)segmentation method(S,I,R,L).RESULTS:OCTA unequivocally demonstrated that the variations in CVD among HCs,T2DM,and GDM groups were statistically significant(P<0.001).In the superficial retinal capillary plexus(sRCP),significant differences were observed in the densities of total microvascular(TMI),microvasculature(MIR),and macrovascular(MAR)between patients with T2DM and HCs(P<0.05).Furthermore,the GDM group exhibited a more substantial reduction in MIR density compared to the T2DM group(P<0.01).In the deep retinal capillary plexus(dRCP),significant differences in the densities of TMI and MIR were identified between the T2DM group and HCs(P<0.05),with a notable difference in TMI density also observed between the GDM and T2DM groups(P<0.01).In the receiver operating characteristic(ROC)curve analysis,the area under the ROC curve(AUC)for TMI in sRCP between the T2DM group and HCs was 0.975,with a 95%confidence interval(CI)of 0.941–1.The AUC for MIR was highest in dRCP,with an AUC value of 0.914 and a 95%CI ranging from 0.847 to 0.981.In comparing the GDM and T2DM groups,the AUC for I region was maximized in sRCP,achieving a value of 0.978 with a 95%CI of 0.953–1.Additionally,the AUC for R region was maximized in dRCP,reaching a value of 0.99 with a 95%CI of 0.975 to 1.CONCLUSION:The sRCP and dRCP densities show higher diagnostic sensitivity for T2DM and GDM.OCTA holds potential as a significant instrument for the early diagnosis and differentiation of T2DM and GDM.