Serial Contours Research Articles

Topologically correct reconstruction of tortuous contour forests

Motivated by the need for correct and robust 3D models of neuronal processes, we present a method for reconstruction of spatially realistic and topologically correct models from planar cross sections of multiple objects. Previous work in 3D reconstruction from serial contours has focused on reconstructing one object at a time, potentially producing inter-object intersections between slices. We have developed a robust algorithm that removes these intersections using a geometric approach. Our method not only removes intersections but can guarantee a given minimum separation distance between objects. This paper describes the algorithm for geometric adjustment, proves correctness, and presents several results of our high-fidelity modeling.

Dominant point detecting based non-uniform B-spline approximation for grain contour

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural geometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw contours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best estimated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.

선수부 선체형상 모델링을 위한 스키닝 연구

This paper presents NURBS skinning for the forebody of ship. NURBS skinning is guessed as a good method to generate the faired surface of ship forebody, but it is very problematic in real ship design to generate resonable surface of ship forbody using skinning, because there are lot of problem to apply skinning and to get reasonable surface. One of main problem is data arrangement with design data. Irregular serial contour data arise so serious compatibility problem of knot vector This paper suggests a whole process using skinning successfully in generating hull form of ship forebody This process includes how to make the data set for skinning and how to execute compatibility procedure.

A new approach for lofted B-spline surface interpolation to serial contours

This paper addresses the problem of B-spline surface interpolation to serial contours, where the number of points varies from contour to contour. A traditional approach to the problem creates a set of B-spline curves via B-spline curve interpolation to each contour, makes them compatible via degree elevation and knot insertion and performs B-spline surface lofting to get a B-spline surface that interpolates them. The approach tends to result in an astonishing number of control points in the lofted B-spline surface. This situation arises mainly from the inevitable process of progressively merging different knot vectors to make the B-spline curves compatible. This paper presents a new approach for fixing this problem. The approach includes a novel process of obtaining a set of compatible B-spline curves from the given contours. The process is based on universal parameterisation [1, 2], allowing the knots to be selected freely but leading to a more stable linear system for B-spline curve interpolation. Since the number of control points in each compatible B-spline curve is equal to the highest number of contour points, the proposed approach can realise efficient data reduction and provide a compact representation of a lofted B-spline surface while keeping the desired surface shape. Some experimental results demonstrate its usefulness and quality.

A hybrid approach to smooth surface reconstruction from 2-D cross sections

This article presents a hybrid approach to smooth surface reconstruction from serial cross sections, where the number of contours varies from section to section. In a triangular surface-based approach taken in most reconstruction methods, a triangular surface is constructed by stitching triangular patches over a triangular net generated from the compiled contours. In the proposed approach, the resulting surface is a G1 composite surface consisting of three kinds of surfaces: skinned, branched, and capped surfaces. Each skinned surface is first represented by a B-spline surface approximating the serial contours of the skinned region and then is transformed into a mesh of rectangular Bezier patches. On branched and capped regions, triangular G1 surfaces are constructed such that the connections between the triangular surfaces and their neighbouring surfaces are G1 continuous. Because each skinned region is represented by an approximated rectangular C2 surface instead of an interpolated triangular G1 surface, the proposed approach can provide more visually pleasing surfaces and realize more efficient data reduction than the triangular surface-based approach. Some experimental results demonstrate its usefulness and quality.

Lofted B-spline surface interpolation by linearly constrained energy minimization

This paper proposes a new approach for lofted B-spline surface interpolation to serial contours, where the number of points varies from contour to contour. The approach first finds a common knot vector consisting of fewer knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Then, it computes from the contours a set of compatible B-spline curves defined on the knot vector by adopting B-spline curve interpolation based on linearly constrained energy minimization. Finally, it generates a B-spline surface interpolating the curves via B-spline surface lofting. As the energy functional is quadratic, the energy minimization problem leads to that of solving a linear system. The proposed approach is efficient in computation and can realize more efficient data reduction than previous approaches while providing visually pleasing B-spline surfaces. Moreover, the approach works well on measured data with noise. Some experimental results demonstrate its usefulness and quality.

Prostate gland motion and deformation caused by needle placement during brachytherapy

Purpose: To determine the extent of edge and gland position changes caused by needle insertion in patients undergoing prostate brachytherapy. Methods and Materials: Nineteen patients with T1–T3 prostate cancer were implanted with the real-time method by using a two-phase peripheral loading technique. Serial contours of the prostate at 5-mm intervals were acquired by the dose-planning system. All of the peripheral needles were then placed and spaced 5–10 mm apart by using the largest transverse ultrasound image as the reference plane. The position of the probe was relocated at the zero plane, and the difference between the preneedle and postneedle zero plane was recorded as the difference in the z axis. Axial ultrasound images were again acquired. The second set of captured images, which matched in number the first set, was contoured over the previously contoured preneedle images. Prostate gland deformation and displacement were determined by comparing the preneedle contoured image with the images captured after needle placement. Deformation was determined by calculating the differences between the edges of the gland as measured at the major axis of the gland ( x and y planes). Displacement was determined by measuring the differences between the center positions of the two contoured structures. Deformation and displacement were determined on each acquired 5-mm image. Differences were compared by student's t test. Results: The mean preneedle prostate volume was 47 ml (range, 21.5–68.7 ml), compared with 48.1 ml (range, 19.4–80.3 ml; p = 0.228) after peripheral needle placement. A median of 16 (range, 12–19) peripheral needles were placed. The median change in the base position of the prostate was 1.5 cm (range of 0 to 3.0 cm; p = 0.0034). The mean x and y deformation was 6.8 mm (median, 7.9 mm; range, 4.3–8.1 mm) and 3.6 mm (median, 3.3 mm; range, 1.0–5.5 mm), respectively. The greatest deformation for any individual slice for x was 21.6 mm and for y was 15.3 mm. The mean number of slices that were found with a >2-, 5-, and 10-mm deformation in the x axis was 7 (range, 3–10), 4 (range, 1–3), and 1 (range, 0–4), respectively. Similar deformation in the y axis was found in 6 (range, 3–10), 2.5 (range, 0–6), and 0.3 (range, 0–2) slices. The mean x and y displacement was 1.9 mm (median, 1.8 mm; range, 0.3–6.6 mm) and 2.8 mm (median, 1.9 mm; range, 2–5.8 mm). The greatest displacement for any individual slice for x was 7 mm and for y was 10 mm. The mean number of slices with a displacement >2, 5, and 10 mm in the x axis was 5 (range, 1–10), 0.8 (range, 0–5), and 0, respectively. Similar displacement in the y axis was found in 5 (range, 0–9), 1.7 (range, 0–7), and 0 slices, respectively. Conclusions: Placing most needles in the periphery results in a minimal prostate volume increase, suggesting little need to overplan the implant when this method is used. However, significant edge and gland position changes caused by the needle insertion did occur. These changes may explain some of the difficulty in reproducing the preplan and should be taken into consideration for all types of prostate brachytherapy planning.

Microcomputer reconstruction of pancreaticobiliary embryogenesis

AbstractThe origin, approximation, and fusion of the dorsal and ventral pancreatic anlage were reconstructed using new microcomputer methodology. Representative human embryos of Carnegie stage 15–17 were studied by digitizing serial contours and creating three‐dimensional computer models. Solid surface color displays showing multiple views of each reconstruction demonstrated developmental relationships and changes between these three critical stages. This exercise demonstrates the power of this new technology for clarifying morphological concepts in research and education.

Shape and texture from serial contours : Lin, C J Int Assoc Math GeolV15, N5, Oct 1983, P617–632

Shape and texture from serial contours : Lin, C J Int Assoc Math GeolV15, N5, Oct 1983, P617–632

Shape and texture from serial contours

Useful shape descriptors for three-dimensional objects can be computed from serial (contour)sections reconstructed into surfaces in three-space. Fischler's algorithm for the caliper diameter of a planar region generalizes in an obvious way to give the major axes of an ellipsoid approximating the shape of a three-dimensional object. The orientation of the object within the three-dimensional sample space, or scene, is a byproduct of the calculation. The anisotropy of the scene can also be described. Fischler's algorithm, together with the classical shape descriptor of perimeter squared error (P2/A)area, can be used to decide the best approximating polygons or ellipses for calculating an object's volume by summing over its successive contours.