3D reconstruction of terrain model based on digital line graphics (DLG) is discussed. An auto-coupling triangles algo-rithm based on triangle topological relationship is put forward, and the topological data model of ...3D reconstruction of terrain model based on digital line graphics (DLG) is discussed. An auto-coupling triangles algo-rithm based on triangle topological relationship is put forward, and the topological data model of complicated terrain is developed. Based on this data model, automatic 3D topological reconstruction of terrain is realized.展开更多
Rapidly and accurately assessing the geometric characteristics of coarse aggregate particles is crucial for ensuring pavement performance in highway engineering.This article introduces an innovative system for the thr...Rapidly and accurately assessing the geometric characteristics of coarse aggregate particles is crucial for ensuring pavement performance in highway engineering.This article introduces an innovative system for the three-dimensional(3D)surface reconstruction of coarse aggregate particles using occlusion-free multi-view imaging.The system captures synchronized images of particles in free fall,employing a matte sphere and a nonlinear optimization approach to estimate the camera projection matrices.A pre-trained segmentation model is utilized to eliminate the background of the images.The Shape from Silhouettes(SfS)algorithm is then applied to generate 3D voxel data,followed by the Marching Cubes algorithm to construct the 3D surface contour.Validation against standard parts and diverse coarse aggregate particles confirms the method's high accuracy,with an average measurement precision of 0.434 mm and a significant increase in scanning and reconstruction efficiency.展开更多
The purpose of this study was to establish a method for measuring the knee valgus angle from the ana- tomical and mechanical axes on three-dimensional reconstruction imaging models, and to use this method for estimati...The purpose of this study was to establish a method for measuring the knee valgus angle from the ana- tomical and mechanical axes on three-dimensional reconstruction imaging models, and to use this method for estimating an average knee valgus angle value for northern Chinese adults. Computed tomographic angiography data in DICOM format for 128 normal femurs from 64 adult subjects were chosen for analysis. After the femur images were subjected to three-dimensional reconstruction, the deepest point in the intercondylar notch （point A）, the midpoint of the medullary cavity 20 cm above the knee-joint line （point B）, and the landmark of the femoral head rotation center （point C） were identified on each three-dimensional model. The knee valgus angle was defined as the angle enclosed by the distal femoral anatomical axis （line AB） and the femoral mechanical axis （line AC）. The average （mean＋SD） of knee valgus angle for the 128 femurs was 6.20°±1.20° （range, 3.05° to 10.64°）. Significant positive correlations were found between the knee valgus angles of the right and left sides and between the knee valgus angle and age. During total knee arthroplasty, choosing a valgus cut angle of approximately 6° may achieve a good result in reestablishing the natural mechanical alignment of the lower extremity for patients of northern Chinese ethnicity. Larger valgus cut angles should be chosen for older patients.展开更多
Background and objective:Intra-corporeal delta-shaped anastomosis(IDA)is an important development in laparoscopic digestive-tract reconstruction.We applied it in laparoscopic right hemicolectomy for right colon cancer...Background and objective:Intra-corporeal delta-shaped anastomosis(IDA)is an important development in laparoscopic digestive-tract reconstruction.We applied it in laparoscopic right hemicolectomy for right colon cancer and compared the short-term outcomes between the patients treated with IDA and conventional extracorporeal anastomosis(EA).Methods:Between 1 January 2016 and 1 October 2017,36 and 50 patients who underwent IDA and EA,respectively,were included.Data on clinicopathological characteristics,surgical outcomes,post-operative recovery and complications were collected and compared between the two groups.Results:Surgical outcomes and clinicopathological characteristics were similar between the two groups except the length of incision,which was significantly shorter in the IDA group than in the EA group(4.660.6 vs 5.660.7 cm,P<0.001).The time to ground activities,fluid diet intake and post-operative hospitalization did not differ between the groups;however,the time to first flatus was significantly shorter in the IDA group than in the EA group(2.860.5 vs 3.260.8 days,P=0.004).The post-operative visual analogue scale for pain was lower in the IDA group than in the EA group on post-operative Day 1(4.060.7 vs 4.561.0,P=0.002)and post-operative Day 3(2.760.6 vs 3.460.6,P<0.001).The surgical complication rates were 8.3 and 16.0%in the IDA and EA groups(P=0.470),respectively.No complications such as anastomotic bleeding,stenosis and leakage occurred in any patient.Conclusions:IDA is safe and feasible and shows more satisfactory short-term outcomes than EA.展开更多
文摘3D reconstruction of terrain model based on digital line graphics (DLG) is discussed. An auto-coupling triangles algo-rithm based on triangle topological relationship is put forward, and the topological data model of complicated terrain is developed. Based on this data model, automatic 3D topological reconstruction of terrain is realized.
基金Supported by the Key R&D Projects in Shaanxi Province(2022JBGS3-08)。
文摘Rapidly and accurately assessing the geometric characteristics of coarse aggregate particles is crucial for ensuring pavement performance in highway engineering.This article introduces an innovative system for the three-dimensional(3D)surface reconstruction of coarse aggregate particles using occlusion-free multi-view imaging.The system captures synchronized images of particles in free fall,employing a matte sphere and a nonlinear optimization approach to estimate the camera projection matrices.A pre-trained segmentation model is utilized to eliminate the background of the images.The Shape from Silhouettes(SfS)algorithm is then applied to generate 3D voxel data,followed by the Marching Cubes algorithm to construct the 3D surface contour.Validation against standard parts and diverse coarse aggregate particles confirms the method's high accuracy,with an average measurement precision of 0.434 mm and a significant increase in scanning and reconstruction efficiency.
基金supported by the Norman Bethune B Program of Jilin University(No.2012216)the Science and Technology Development Program of Jilin Province(No.20100750),China
文摘The purpose of this study was to establish a method for measuring the knee valgus angle from the ana- tomical and mechanical axes on three-dimensional reconstruction imaging models, and to use this method for estimating an average knee valgus angle value for northern Chinese adults. Computed tomographic angiography data in DICOM format for 128 normal femurs from 64 adult subjects were chosen for analysis. After the femur images were subjected to three-dimensional reconstruction, the deepest point in the intercondylar notch （point A）, the midpoint of the medullary cavity 20 cm above the knee-joint line （point B）, and the landmark of the femoral head rotation center （point C） were identified on each three-dimensional model. The knee valgus angle was defined as the angle enclosed by the distal femoral anatomical axis （line AB） and the femoral mechanical axis （line AC）. The average （mean＋SD） of knee valgus angle for the 128 femurs was 6.20°±1.20° （range, 3.05° to 10.64°）. Significant positive correlations were found between the knee valgus angles of the right and left sides and between the knee valgus angle and age. During total knee arthroplasty, choosing a valgus cut angle of approximately 6° may achieve a good result in reestablishing the natural mechanical alignment of the lower extremity for patients of northern Chinese ethnicity. Larger valgus cut angles should be chosen for older patients.
基金This work was supported by Beijing Terry Fox Run Foundation of Cancer Foundation of China(No.LC2016B10)Chinese Academy of Medical Sciences Initiative for Innovative Medicine(CAMS-2017-I2M-4-002)Postgraduate Innovation Fund Project of Peking Union Medical College in 2018(2018-1002-02-26).
文摘Background and objective:Intra-corporeal delta-shaped anastomosis(IDA)is an important development in laparoscopic digestive-tract reconstruction.We applied it in laparoscopic right hemicolectomy for right colon cancer and compared the short-term outcomes between the patients treated with IDA and conventional extracorporeal anastomosis(EA).Methods:Between 1 January 2016 and 1 October 2017,36 and 50 patients who underwent IDA and EA,respectively,were included.Data on clinicopathological characteristics,surgical outcomes,post-operative recovery and complications were collected and compared between the two groups.Results:Surgical outcomes and clinicopathological characteristics were similar between the two groups except the length of incision,which was significantly shorter in the IDA group than in the EA group(4.660.6 vs 5.660.7 cm,P<0.001).The time to ground activities,fluid diet intake and post-operative hospitalization did not differ between the groups;however,the time to first flatus was significantly shorter in the IDA group than in the EA group(2.860.5 vs 3.260.8 days,P=0.004).The post-operative visual analogue scale for pain was lower in the IDA group than in the EA group on post-operative Day 1(4.060.7 vs 4.561.0,P=0.002)and post-operative Day 3(2.760.6 vs 3.460.6,P<0.001).The surgical complication rates were 8.3 and 16.0%in the IDA and EA groups(P=0.470),respectively.No complications such as anastomotic bleeding,stenosis and leakage occurred in any patient.Conclusions:IDA is safe and feasible and shows more satisfactory short-term outcomes than EA.
