【０００１】[0001]
【産業上の利用分野】この発明は、頭部や心臓の部分な
どにおいて各組織の境界面を表わす立体モデルの作成法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of creating a three-dimensional model representing the boundary surface of each tissue in the head or the heart.
【０００２】[0002]
【従来の技術】脳磁計や脳波計あるいは心磁計、心電図
などを用いて人間の脳や心臓の磁気あるいは電圧を測定
し、それらのデータより電流双極子を算出する際など
に、頭部や心臓の各部の導電率の違いに基づいて作成し
た立体モデルが使用される。2. Description of the Related Art The magnetic field or voltage of a human brain or heart is measured using a magnetoencephalography meter, an electroencephalograph, a magnetocardiograph, or an electrocardiogram, and when calculating a current dipole from the data, the head or heart is measured. A three-dimensional model created based on the difference in conductivity of each part of is used.
【０００３】境界要素法を用いて被検者頭部内に仮定し
た神経活動電流源が測定点に作る磁束密度を求める場合
の頭部モデルについては、ＭＲＩ装置を用いて人間の頭
部を撮影して得た多数の断層面についてのＭＲ像上で、
空間−頭表皮、頭表皮−頭蓋骨、頭蓋骨−脳脊髄液の各
境界を抽出し、３層精密モデルを作成することが知られ
ている（J.W.H.Meijs,et al "The Influence of Variou
s Head Models on EEGs and MEGs",Functional Brain I
maging,pp31-45,1988）。As for the head model in the case of obtaining the magnetic flux density created at the measurement point by the neural activity current source assumed in the head of the subject by using the boundary element method, the human head is imaged by using the MRI apparatus. On the MR images of many tomographic planes obtained by
It is known that the three-layer precision model is created by extracting each boundary of space-cephalic epidermis, cephalic epidermis-skull bone, and skull-cerebrospinal fluid (JWHMeijs, et al "The Influence of Variou
s Head Models on EEGs and MEGs ", Functional Brain I
maging, pp31-45, 1988).
【０００４】また、多数の断層像から境界立体像を作
り、その内部に、多数の小さな三角形要素に分割された
凸正多面体を想定し、それを上記の立体像に投影するこ
とにより立体モデルを作成することも考えられている
（特願平２−４１６１３９号参照）。Further, a boundary stereoscopic image is created from a large number of tomographic images, a convex regular polyhedron divided into a large number of small triangular elements is assumed in the boundary stereoscopic image, and the solid polyhedron is projected onto the stereoscopic image to form a stereoscopic model. It is also considered to create it (see Japanese Patent Application No. 2-416139).
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、従来
の、一つの断層面のＭＲ画像で求めた境界線と隣接する
断層面のＭＲ画像で求めた境界線とをつなぎ合わせて三
角形面素を形成する立体モデル作成法では、隣接する断
層面の境界線の数が異なる場合正しい形状を表現できな
いし、また三角形面素の大きさを変えたモデルを作成す
ることはかなり困難であるという問題がある。However, the conventional boundary line obtained by the MR image of one tomographic plane and the conventional boundary line obtained by the MR image of the tomographic plane are connected to form a triangular plane element. The three-dimensional model creation method has a problem that a correct shape cannot be expressed when the number of boundary lines of adjacent fault planes is different, and it is quite difficult to create a model in which the size of a triangular plane element is changed.
【０００６】また、多数の小さな三角形要素に分割され
た凸正多面体を立体像に投影する方法では、複雑な形状
の場合、投影できない部分が生じることがある。これを
解決するため、仮境界面を想定して多段階の投影を行な
うことも提案されているが、処理が複雑な上、仮境界面
の設定については人間の手による入力が必要であること
から、手間がかかるという問題がある。Further, in the method of projecting a convex regular polyhedron divided into a large number of small triangular elements on a stereoscopic image, in the case of a complicated shape, there may be a portion that cannot be projected. In order to solve this, it has been proposed to perform multi-step projection assuming a provisional boundary surface, but the process is complicated and human input is required to set the provisional boundary surface. Therefore, there is a problem that it takes time and effort.
【０００７】この発明は、上記に鑑み、立体形状をより
正確に表現できるとともに、複雑な立体形状についても
コンピュータによる計算処理のみで容易にモデル化でき
る、立体モデル作成法を提供することを目的とする。In view of the above, it is an object of the present invention to provide a three-dimensional model creation method capable of expressing a three-dimensional shape more accurately and easily modeling a complicated three-dimensional shape only by calculation processing by a computer. To do.
【０００８】[0008]
【課題を解決するための手段】上記の目的を達成するた
め、この発明による立体モデル作成法においては、立体
の境界面を計測し、所定の間隔ごとの多数のスライス面
上での境界面形状を求め、つぎにこの各スライス面ごと
の境界面形状を所定間隔の点列に変換し、その後、隣り
合うスライス面間で点列の各点を三角形または四角形が
形成されるように結ぶことが特徴となっている。In order to achieve the above object, in the method for creating a stereo model according to the present invention, the boundary surface of a solid is measured, and the boundary surface shape on a large number of slice planes at a predetermined interval is measured. Then, the boundary surface shape for each slice plane is converted into a sequence of points at predetermined intervals, and then each point of the sequence of points can be connected between adjacent slice planes so that a triangle or a quadrangle is formed. It is a feature.
【０００９】[0009]
【作用】計測した境界面より所定の間隔ごとの多数のス
ライス面上での境界面形状を求め、さらにこれを点列に
変換し、隣り合うスライス面間で点列の各点を三角形ま
たは四角形が形成されるように結ぶことにより、三角形
要素または四角形要素で表わされた立体モデルを作成で
きる。境界面を計測してしまえば、その後の処理はすべ
てコンピュータによる計算で行なうことができるので、
手間がかからず、容易である。スライス面間隔および点
列の間隔を変えれば、複雑な形状を正確に表現すること
ができる。The shape of the boundary surface on a large number of slice surfaces at predetermined intervals is calculated from the measured boundary surface, and this is converted into a point sequence, and each point of the point sequence between adjacent slice surfaces is a triangle or a quadrangle. The three-dimensional model represented by the triangular element or the quadrangular element can be created by tying so as to form. Once you have measured the boundary surface, all the subsequent processing can be done by computer calculation,
It is effortless and easy. By changing the slice plane interval and the interval of the point sequence, it is possible to accurately represent a complicated shape.
【００１０】[0010]
【実施例】以下、この発明の一実施例について図面を参
照しながら詳細に説明する。この発明の一実施例では頭
部モデルを作成することとしており、図１のフローチャ
ートに示すように、まず頭部の組織の境界面（形状）を
計測し、座標値としてコンピュータに取り入れる。その
境界面計測方法としては、ＭＲ装置やＸ線ＣＴ装置など
を用いて多数のスライス断層像（ＭＲＩ像、ＣＴ像）を
撮像し、つぎにその多数のスライス断層像のそれぞれに
ついて、空間−頭表皮境界、頭表皮−頭蓋骨境界、頭蓋
骨−脳脊髄液境界などの境界を抽出する方法や、三次元
ディジタイザを用いて頭部の形状をトレースする方法な
どを採用できる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In one embodiment of the present invention, a head model is created, and as shown in the flowchart of FIG. 1, first, the boundary surface (shape) of the tissue of the head is measured, and the measured value is taken into the computer as coordinate values. As the boundary surface measuring method, a large number of slice tomographic images (MRI images, CT images) are captured using an MR device or an X-ray CT device, and then the space-head is taken for each of the large number of slice tomographic images. A method of extracting a boundary such as an epidermis boundary, a head epidermis-skull bone boundary, a skull-cerebrospinal fluid boundary, or a method of tracing the shape of the head using a three-dimensional digitizer can be adopted.
【００１１】こうして得た頭部モデルの境界面形状をス
プライン補間等の補間技術を用い、図２に示すように、
間隔ｍ（ｍｍ）の多数のスライス面１の各々において境
界面形状２として表わす。The boundary surface shape of the head model thus obtained is subjected to an interpolation technique such as spline interpolation as shown in FIG.
It is represented as a boundary surface shape 2 in each of a large number of slice planes 1 at intervals m (mm).
【００１２】さらに、多数のスライス面１の各々に示さ
れた境界面形状を、補間技術を用いることにより、図３
に示すような間隔ｎ（ｍｍ）の点列３に変換する。これ
らの点列３は、頭部モデル境界面を三角要素で表わす場
合の、その各三角形の頂点に対応するものであり、図２
のスライス面１の間隔ｍおよび図３の点間隔ｎの値を変
えることにより、その境界面を表わすための三角形要素
の大きさを変化させることができる。Furthermore, by using the interpolation technique, the boundary surface shapes shown in each of the plurality of slice planes 1 can be obtained as shown in FIG.
It is converted into a point sequence 3 having an interval n (mm) as shown in. These point sequences 3 correspond to the vertices of the respective triangles when the head model boundary surface is represented by triangular elements.
By changing the values of the interval m of the slice plane 1 and the point interval n of FIG. 3, it is possible to change the size of the triangular element representing the boundary surface.
【００１３】つぎに、図４に示すように、隣り合う２つ
のスライス面１、１の間で、点列３を構成する各点を、
そのスライス面間で三角形が形成されるようにして、結
ぶ。このとき、その隣り合う２つのスライス面１、１で
は、点列３を構成する点の数が異なるため、つぎのよう
にして点同士を結び合わせる。まず、図４に示すよう
に、ｉスライス面での点の数をａ個、（ｉ＋１）スライ
ス面での点の数をｂ個ととする。ｉスライス面の１個の
点から（ｉ＋１）スライス面のｐ個の点にそれぞれ直線
を引いていき、そのｊ回（ｉスライス面のｊ個の点ご
と）に１回はｉスライス面の１個の点から（ｉ＋１）ス
ライス面のｐ＋１個の点にそれぞれ直線を引く。ただ
し、（ｉ＋１）スライス面側では、ｉスライス面の１個
の点に結ばれている複数点の端の点が、ｉスライス面側
の他の１個の点に、２重に結ばれるようにする。Next, as shown in FIG. 4, between the two adjacent slice planes 1 and 1, the points forming the point sequence 3 are
Tie them so that a triangle is formed between the slice planes. At this time, since the number of points forming the point sequence 3 is different between the two adjacent slice planes 1 and 1, the points are connected as follows. First, as shown in FIG. 4, the number of points on the i slice plane is a, and the number of points on the (i + 1) slice plane is b. A straight line is drawn from one point on the i-slice plane to each of the p points on the (i + 1) slice plane, and once every j times (every j points on the i-slice plane), one line is drawn on the i-slice plane. Straight lines are drawn from these points to p + 1 points on the (i + 1) slice plane. However, on the (i + 1) slice plane side, a point at the end of a plurality of points connected to one point on the i slice plane is doubly connected to another point on the i slice plane side. To
【００１４】そして、このときのｐ、ｊは、 ｐ≦（ｂ／ａ）＋１ ｊ≦ａ／（ｂ−ｐａ＋ａ−１） をそれぞれ満足する最大の整数値とする。図４のように
ａ＝１０、ｂ＝１５としたとき、ｐ＝２、ｊ＝２であ
る。Then, p and j at this time are the maximum integer values which respectively satisfy p≤ (b / a) +1 j≤a / (b-pa + a-1). When a = 10 and b = 15 as shown in FIG. 4, p = 2 and j = 2.
【００１５】こうしてスライス面１、１間で点列３の点
同士を直線で結んでいって、点が余ったときは、その余
った点は最終点にすべて結ぶこととする。In this way, when the points of the point sequence 3 are connected by a straight line between the slice planes 1 and 1, and when there are extra points, the extra points are all connected to the final point.
【００１６】このような方法で、実際に、頭蓋骨の内面
を頭部モデル境界面とし、スライス面の間隔ｍ＝１０
（ｍｍ）、点列の点間隔ｎ＝１０（ｍｍ）として立体モ
デルを作成してみたところ、図５に示すようなものが得
られた。この図５において、Ａは上方から見た上面図、
Ｂは前方から見た正面図、Ｃは右方向から見た側面図で
ある。By such a method, the inner surface of the skull is actually used as the head model boundary surface, and the interval m between slice planes is m = 10.
(Mm) and a point array point interval n = 10 (mm), a three-dimensional model was created, and the result shown in FIG. 5 was obtained. In FIG. 5, A is a top view seen from above,
B is a front view seen from the front, and C is a side view seen from the right.
【００１７】なお、スライス面の間隔ｍ、点列の点間隔
ｎは、全部の領域で均一である必要はなく、特定領域の
みで変化させることもでき、これにより境界面要素（三
角形要素）の大きさを部分的に変えることができるの
で、部分的に複雑になっている形状の生体についてのモ
デル化も容易である。また、上記の実施例では三角形要
素により立体モデルを作成することとして、点列の各点
を、三角形が形成されるように結んでいるが、四角形が
形成されるようにして結び四角形要素により表現される
立体モデルを作成することもできる。The interval m of the slice plane and the point interval n of the point sequence do not have to be uniform in all the areas, and can be changed only in a specific area, whereby the boundary surface element (triangular element) can be changed. Since the size can be partially changed, it is easy to model a living body having a partially complicated shape. In addition, in the above-described embodiment, the three-dimensional model is created by the triangular elements, and each point of the point sequence is connected so as to form a triangle. It is also possible to create a three-dimensional model.
【００１８】[0018]
【発明の効果】以上実施例について説明したように、こ
の発明の立体モデル作成法によれば、複雑な立体形状の
生体についても、コンピュータによる計算処理のみで、
境界面要素を決定することができるため、より正確に表
現した立体モデルを容易に作成できる。さらに、スライ
ス面間隔、点列の点間隔を変えることにより、立体モデ
ルの構成要素数や各要素の大きさを自由に変えることが
できるし、部分的にこのような変化を行なうことができ
るため、どのような立体形状であってもそれに対応して
モデルを作成することが容易である。As described in the above embodiments, according to the three-dimensional model creating method of the present invention, even a living body having a complicated three-dimensional shape can be calculated only by a computer.
Since the boundary surface element can be determined, a more accurate three-dimensional model can be easily created. Furthermore, the number of constituent elements of the stereo model and the size of each element can be freely changed by changing the slice plane interval and the point interval of the point sequence, and such a change can be partially performed. It is easy to create a model corresponding to any three-dimensional shape.
【図１】この発明の一実施例のフローチャート。FIG. 1 is a flowchart of an embodiment of the present invention.
【図２】同実施例の一つの工程を表わす図。FIG. 2 is a view showing one process of the same embodiment.
【図３】同実施例のつぎの工程を表わす図。FIG. 3 is a diagram showing the next step of the same embodiment.
【図４】同実施例のさらにそのつぎの工程を表わす図。FIG. 4 is a diagram showing a step subsequent to the step of the example.
【図５】頭蓋骨内面の立体モデルを表わす図。FIG. 5 is a diagram showing a three-dimensional model of the inner surface of the skull.
１ スライス面 ２ 境界面形状 ３ 点列 1 Slice surface 2 Boundary surface shape 3 point sequence
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22473892AJP3191829B2 (en) | 1992-07-31 | 1992-07-31 | 3D model creation method |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22473892AJP3191829B2 (en) | 1992-07-31 | 1992-07-31 | 3D model creation method |
| Publication Number | Publication Date |
|---|---|
| JPH0647022Atrue JPH0647022A (en) | 1994-02-22 |
| JP3191829B2 JP3191829B2 (en) | 2001-07-23 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22473892AExpired - Fee RelatedJP3191829B2 (en) | 1992-07-31 | 1992-07-31 | 3D model creation method |
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| JP (1) | JP3191829B2 (en) |
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