JPH04124784A - Method for generating fault plane from three-dimensional picture - Google Patents

Abstract

PURPOSE:To speedily prevent the deterioration of picture quality with the aid of arbitrary profile angle by deciding the direction of interpolation from the angle of an object fault plane, deciding the density value of a point on the fault plane from the interpolation, and distributing the density value in a two-dimensional plane after projection. CONSTITUTION:Two coordinates are chosen from among coordinates X, Y, Z on the profile to be projected, and the rest one coordinate is obtained by the formula on the fault plane. There are three ways in this selection. The amount of change of a projection point is determined by this way of selection, and the method for interpolation with the smallest amount of change among these is utilized to the generation of fault plane afterwards. Then, the value of the object point of the projection is decided while performing interpolation in the direction of the interpolation adapted in the front stage. On the other hand, the point is projected to a two-dimensional coordinate system 10 formed on the fault plane based on the projection conversion formula. After the projection, the addition of the value of a point 11 is performed while distributing it to a neighboring lattice point 12, and the fault picture is finally obtained. Thus, high-quality fault plane generation can be performed with the small number of access of a three-dimensional external memory.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to X! The present invention relates to a tomographic plane generation method for displaying data on a two-dimensional display device such as a two-dimensional display or printer in a three-dimensional image obtained by stacking two-dimensional images such as ICT images.

[Prior art]

Based on 3D image data of an object placed in 3D space,
When projecting onto a certain two-dimensional plane or cutting at a certain cross section to obtain a tomographic image, data interpolation processing is required.

Conventionally, the following two interpolation methods have been used in this projection transformation.

First, as a first interpolation method, as shown in FIG. 7 to determine the interpolation method.

With this interpolation method, as shown in FIG. 5, a good image quality can be obtained by interpolating from 8 neighboring points, but the number of times the three-dimensional memory is referenced is extremely large and the processing time is long. Next, as a second interpolation method, as shown in FIG. This is a method in which the values are distributed to neighboring grid points 12 on the two-dimensional projection plane 10 and added to the original values. This interpolation method is effective when projecting the entire three-dimensional space, and also requires fewer references to the three-dimensional memory and can be executed at high speed.

[Problem to be solved by the invention]

However, when generating a cross-section, there are problems in that the points on the cross-section do not lie on grid points, and the image quality may deteriorate significantly depending on the inclination angle of the cross-section. Therefore, although the speed is slow, the first interpolation method is used for tomographic plane generation.6 The present invention has been made to solve the above problems, and the purpose of the present invention is to The object of the present invention is to provide a technique that can prevent deterioration of image quality while maintaining high speed when generating tomographic planes.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for Solving the Problems] In order to achieve the above object, the present invention sequentially obtains coordinates on a two-dimensional projection plane corresponding to grid points in a three-dimensional space, and calculates values greater than or equal to the three-dimensional grid points. By distributing it to neighboring grid points on this two-dimensional projection plane and adding it to the original value, 3
In a tomographic plane generation method that obtains an arbitrary tomographic image from dimensional image data, the interpolation direction is determined based on the angle of the target tomographic plane, the density value of a point on the tomographic plane is determined by interpolation in that direction, and the The most important feature is distributing density values on a dimensional plane.

[Effect]

According to the above-mentioned means, the interpolation direction is determined based on the angle of the target tomographic plane, the density value of the point on the tomographic plane is determined by interpolation in that direction, and the density values on the two-dimensional plane after projection are distributed. , it is possible to prevent deterioration of image quality at high speed and at any cross-sectional angle.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In addition, in all the figures for explaining the embodiment, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

FIG. 1 is an explanatory diagram for explaining generation of a tomographic plane by X-direction interpolation in one embodiment of the tomographic plane generation method from a three-dimensional image of the present invention, and FIG. 2 is a diagram showing parameters of a tomographic plane in this embodiment. α.

Figure 3 is an explanatory diagram to explain the interpolation directions in three directions in this embodiment. Figure 4 is an explanatory diagram to explain the interpolation directions in three directions in this embodiment. FIG. 3 is a directional area division diagram.

In Figures 1 to 4, 1 is a three-dimensional space, 2 is a cross section,
3 is a grid point on the Y-Z plane, 4 is a perpendicular from grid point 3, and 5 is a vertical! ! 4 and the cross section 2, 6 is the lattice point on the vertical NlA4, 10 is the two-dimensional projection plane (coordinate system of the cross section), 11
is a point on plane 10 corresponding to point 5, 12 is a grid point on plane lo, 20 is a perpendicular vector (modulus g) drawn from the origin to section 2, and 21 is a projection of perpendicular vector 20 onto the X-Y plane. The vector 22 is the angle (β) between the X-Y plane and the perpendicular vector 20, and 23 is the angle (α) between the vector 21 and the X axis.
).

The method of generating a tomographic plane from a three-dimensional image of this embodiment uses the second interpolation method described in the conventional technique as a projection target for points other than grid points, and adapts it to the inclination angle of the tomographic plane. This is to prevent deterioration of image quality.

Hereinafter, the method of generating a tomographic plane from a three-dimensional image according to this example will be explained as follows.
This will be explained in detail with reference to FIG.

As shown in Figure 2, a three-dimensional space 1 is defined by the X, Y, and Z axes, and 0≦x<ny+o≦Y < n v + O≦Z
<Assume that there are values only at integer coordinates in the interval n2.

In FIG. 1, first, the coordinates of a point on the cross section to be projected are determined. Select two coordinates from X, Y, and Z, and
For the two coordinates, select all combinations that are integers. For example, let's say Y and z.

The remaining coordinate is determined from the equation of the tomographic plane.

In this example, it is X. As shown in FIG. 3, there are three ways to select this. The amount of change of the projection point on the two-dimensional plane when one of the two selected coordinates, for example, Y, is changed, and the amount of change of the projection point on the two-dimensional plane when one of the two selected coordinates, for example, Y, is changed, and the amount of change of the projection point on the two-dimensional plane when one of the two selected coordinates, for example, 2 is changed by 1.
The amount of change in the coordinates of the projection point on the dimensional plane is determined from the actual projection transformation formula, and the largest variable among these variables is taken as the amount of change in this selection method.

The amount of change in the projection point is determined by each of the three selection methods, and the interpolation method that provides the smallest amount of change is adopted as the interpolation method that will be used to generate the cross-sectional layer from now on.

Next, the value of the projection target point is determined by interpolation in the interpolation direction adopted in the previous step. In the example shown in FIG. 1, the X and Y coordinates are selected and interpolated in two directions. In this case, let X and Y be O≦X
For a set of 01·n9 integers in the range <n, O≦Y<n, the Z coordinate value on the tomographic plane is determined, and the value of point 5 is determined by interpolating from the neighboring point 6.

On the other hand, that point is projected onto a two-dimensional coordinate system 10 formed on the cross section based on a projection transformation formula. The distribution used in the second method described in the conventional technique is the same as in the previous method, by adding the value of the point 11 after projection while distributing the value to the neighboring grid points 12, and finally A tomographic image can be obtained.

That is, as shown in FIG.
is the angle (β) between the X-Y plane and the vertical vector 20, 2
3 describes the process of obtaining a cross-sectional image in the three-dimensional space 1 with an angle (α) between the vector 21 and the X-axis as an example.

The projection transformation formula from the locus @ (X, Y, Z) in the three-dimensional space 1 to the coordinates (x + y) on the two-dimensional plane is expressed as equation (1).

・　・　・(1) The equation of the cross section is Equation (2).

X cos a cosβ tenY sin a cosβ
+Z sinβ=k... (2) However, k is the distance between the origin (0, 0, 0) and the cross section.

First, the interpolation direction is determined based on the angle (α, β) of the tomographic plane. By substituting equation (2) into equation (1), eliminating one parameter among x, y, and z, and finding the relationship between the amount of change at each coordinate, equations (3) to (5) are obtained. It will be done.

In equations (3) to (5), when the absolute value of each element of the coefficient matrices A, B, and C is large, the points projected onto the two-dimensional plane become sparse, and there are gaps in the data of the grid points. It will happen. Among the three interpolation methods shown in FIG. 3, the interpolation method with the smallest coefficient generates a tomographic plane with fine image quality. This coefficient is determined by the variables α and β that determine the tomographic plane.
Change this α.

We decided to select the interpolation method depending on β.

For example, when α=c and β=τ, the coefficients A, B, and C are respectively.

Therefore, at this angle, interpolation in the Z direction is used.

When a conversion formula to a tomographic plane is determined in this manner, the image quality is superior or inferior depending on the angles α and β of the tomographic plane. When generating a tomographic plane, an interpolation direction with good image quality can be determined from the given α and β.

When using the conversion formula (1) listed in this example, the fourth
As shown in the figure, interpolation in the X direction is applied to areas with diagonal lines, interpolation in the Y direction is applied to areas with horizontal stripes, and interpolation in two directions is applied to areas with vertical stripes.

The interpolation direction is determined according to the method described above, the points on the tomographic plane to be converted are found, and the values are first distributed to neighboring grid points on the two-dimensional plane of the projection light.

As can be seen from the above explanation, according to this embodiment, the interpolation direction is determined based on the angle of the target tomographic plane, the density value of the point on the tomographic plane is determined by interpolation in that direction, and the two-dimensional By distributing the density values on a plane, it is now possible to apply the conventional method (second interpolation method) that could not be applied to tomographic plane generation, allowing high-quality tomographic plane generation with a small number of accesses to the 3D external memory. becomes possible.

This makes it possible to prevent deterioration of image quality at high speed and at any cross-sectional angle.

The present invention has been specifically described above based on examples, but 1.
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As explained above, according to the present invention, the interpolation direction is determined based on the angle of the target tomographic plane, the density value of the point on the tomographic plane is determined by interpolation in that direction, and the density value of the point on the tomographic plane after projection is determined. By distributing density values, it is possible to prevent deterioration of image quality at high speed and at any cross-sectional angle.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining generation of a tomographic plane by X-direction interpolation in an embodiment of the tomographic plane generation method from a three-dimensional image of the present invention. FIG. α. FIG. 3 is an explanatory diagram for explaining the interpolation directions in three directions in this embodiment. FIG. 4 is an explanatory diagram for explaining the interpolation directions in three directions in this embodiment. Directional area division diagram. FIG. 5 is an explanatory diagram for explaining the problem of tomographic plane generation using the conventional first interpolation method. FIG. 6 is an explanatory diagram for explaining the problem of tomographic plane generation using the conventional second interpolation method. It is an explanatory diagram for explanation. In the figure, 1... three-dimensional space, 2... cross section, 3... Y
- Grid points on the Z plane, 4... perpendicular from grid point 3,
5... Intersection of perpendicular line 4 and cross section 2, 6... Grid point on perpendicular line 4, 10... Two-dimensional projection plane (coordinate system of cross section), 1
1... Point on plane 10 corresponding to point 5, 12... Grid point on plane 10, 20... Perpendicular vector drawn from the origin to section 2, 21... Perpendicular vector 20 as x- Y
Vector projected onto a plane, 22... Angle (β) between the X-Y plane and the perpendicular vector 20, 23... Vector 21
and the angle (α) formed by the X axis.

Claims (1)

[Claims] (1) Sequentially find the coordinates on the two-dimensional projection plane corresponding to the grid points in the three-dimensional space, distribute the values greater than or equal to those three-dimensional grid points to neighboring grid points on this two-dimensional projection plane, and return them to the original values. In a tomographic plane generation method that obtains an arbitrary tomographic image from three-dimensional image data by adding up, the interpolation direction is determined based on the angle of the target tomographic plane, and the density value of a point on the tomographic plane is determined by interpolation in that direction. A tomographic plane generation method characterized by determining the density value on a two-dimensional plane after projection.