JPH0518940A - Ultrasonic three-dimensional image display device - Google Patents

Abstract

PURPOSE:To enable a surface extraction to the automated and at the same time a precise display to be made for automating operation and improving measurement accuracy by creating parameters of Phong shading method and then determining brightness based on a surface extraction by the threshold method. CONSTITUTION:A normal vector of a plane passing through a position which is read by a surface position information memory portion 25 is obtained and a result is stored in a normal vector component memory portion 29, parameters such as position and intensity of a light source are set by a Phong shading parameter setting portion 19, brightness of each fine plane is determined by the Phong shading method according to this each parameter and the normal vector, and then a final brightness information is displayed on a CRT 33. All normal vectors of objects are automatically calculated after calculation and storage of surface information, brightness is determined by position of the light source and an observer and the normal vector by the Phong shading method and is assigned to each fine plane, thus enabling a style, etc., of recessed and projecting portions of a surface of an organization to be displayed in details.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic three-dimensional image display device, and more particularly to improvement of a brightness display mechanism of the ultrasonic three-dimensional image display device.

[0002]

2. Description of the Related Art In recent years, research on three-dimensional display based on a plurality of tomographic images obtained from the inside of a living body has been advanced, and is useful for treatment and diagnosis. In order to effectively use this three-dimensional display for treatment and diagnosis, the stereoscopic effect of the object must be effectively expressed. Therefore, brightness is added according to the distance from the object. A surface extraction method based on the threshold method, which performs grayscale display, is generally used.

By the way, the grayscale display means based on the threshold method is performed based on the principle as shown in FIG. That is, the echo intensity based on the distance from the viewpoint is sequentially measured, and since a boundary with the object is where the abrupt change of the echo intensity occurs, a threshold value is set in advance, and the threshold value and the echo intensity are set. Is compared for each distance, and the distance at which the echo intensity exceeds the threshold is
It is defined as the distance to the surface of the object. In this way, the threshold value is set in advance, the threshold value and the echo intensity are compared for each distance, and the distance when the echo intensity exceeding the threshold value is detected is detected, whereby the object surface is viewed from the viewpoint. It is possible to detect the distance to.

Further, in the field of computer graphics, tomographic images from CT and MRI are
Luminance is added by the shading method, so that a rough tomographic image is interpolated.

Here, FIG. 9 is an explanatory view for explaining the mechanism of three-dimensional construction by the von shading method. According to the three-dimensional construction method using the Phong shading method, first, a boundary corresponding to the target surface is extracted from each of the obtained tomographic images, and then a surface is attached between the surface information of each tomographic image. Then, the normal vector of each of these attached surfaces is calculated. Then, when the normal vector of each surface is calculated, the brightness is added based on the normal vector. In this way, the brightness is added based on the inclination of the normal vector that is calculated and defined for each of the minute planes between the tomographic images, so that the luminance according to the inclination of the minute planes is added. It is supposed to be done.

[0006]

However, in the three-dimensional display method based on the threshold method, it is possible to obtain a three-dimensional image with a perspective, but small unevenness present at approximately the same distance from the observer. Has the drawback of being displayed at the same brightness. Therefore, it is suitable for displaying a rough shape, but not for displaying detailed information, and the user should understand the surface condition, that is, whether the surface is smooth or uneven. However, there is a problem in that one of the important information is missing and the diagnosis must be performed in the absence of the important information.

The present invention has been made in view of the above problems, and an object thereof is to display a display image in which small irregularities on the surface of an object are emphasized and displayed and the entire object can be grasped three-dimensionally. It is an object of the present invention to provide an ultrasonic three-dimensional image display device that can be automatically and easily constructed.

[0008]

In order to solve the above problems, in the ultrasonic three-dimensional image display device according to the present invention, the threshold value method and the phon shading method are combined to form the surface of the object. It is characterized by determining the brightness of.

That is, in the ultrasonic three-dimensional image display device according to the present invention, the surface position extracting means for extracting the position of the surface of the object by the threshold method and the object extracted by the surface position extracting means. Based on the position information of the surface of the object, the surface of the object is divided into minute planes and normal vector calculating means for calculating the normal vector of each of these minute planes, and the normal vector calculating means Brightness calculation means for calculating the brightness of the surface of the object by the von shading method from the normal vector and the position of the viewpoint and the light source.

[0010]

In the ultrasonic three-dimensional image display device of the present invention having the above-mentioned structure, the points on the surface of the object are defined by the threshold method and the surface of the object is extended by the phon shading method. The brightness is determined based on the detailed surface state of the object surface created by this.

That is, when the surface position of the object is extracted by the surface position extracting means, the surface of the object is divided into minute planes based on the surface position information by the threshold method of the object surface, and These normal vectors are calculated by the normal vector calculation means. When the normal vector is calculated, the positions of the viewpoint and the light source are used as parameters in the von shading method, and the brightness of the object surface is calculated.

[0012]

FIG. 1 is a block diagram showing the functional arrangement of an ultrasonic three-dimensional image display apparatus according to a preferred embodiment of the present invention.

The present apparatus includes an ultrasonic diagnostic apparatus 11 for obtaining echo information from the inside of a living body and a peripheral control section 13 connected to the ultrasonic diagnostic apparatus 11. The peripheral control section 13 is connected to a CPU 17 via a bus line 15. It is connected. Further, the bus line 15 includes a phon shading parameter setting unit 19, a three-dimensional data memory unit 21, a frame buffer memory unit 23, a surface position information memory unit 25, a surface position detection unit 27, and a normal vector. A component memory unit 29,
The high-speed arithmetic processor 31 is connected. Furthermore, a CRT 33 is connected to the frame buffer memory unit 23 so that the data temporarily stored in the frame buffer memory unit 23 can be displayed on the CRT 33 as an image.

Here, FIG. 2 is a flow chart showing the operation flow of the ultrasonic three-dimensional image display apparatus according to this embodiment.

As shown in FIG. 2, in this apparatus, first, echo data is collected by the ultrasonic diagnostic apparatus 11 from inside the living body (S101). Then, the echo data is composed of a plurality of tomographic images with sufficiently small intervals, and is stored in the three-dimensional data memory unit 21 through the peripheral control unit 13 (S102). Then, the surface position detection unit 27 detects the surface position of the object based on the data of each tomographic image stored in the three-dimensional data memory unit 21, and this position data is stored in the surface position information memory unit 25. (S103). Note that this S101 to S10
The operations up to 3 are performed on all surfaces of the object.

Here, the adjacent surface position information is read from the surface position information memory unit 25, the normal vector of the plane passing through the read position is obtained (S104), and the result is stored in the normal vector component memory unit 29. The phon shading parameter setting unit 19 sets parameters such as the position of the light source and the intensity of the light source (S10).
5). Then, from the parameters set in S105 and the normal vector calculated in S104, the brightness of each minute plane is determined by the von shading method (S106). Note that this operation is performed for all normal vectors. Finally, the determined brightness information is stored in the frame buffer memory unit 23 (S107) and displayed on the CRT 33 (S1).
08).

The surface extraction by the threshold method is the same as the conventional method. As shown in FIG. 8, a virtual viewpoint is set for the object and the line of sight is directed toward the object. put out. Then, at the viewpoint, the preset threshold value is compared with the echo data on the line of sight. here,
Since the echo intensity changes rapidly on the surface of the object due to the difference in acoustic impedance, if the threshold is set appropriately, the position where the echo data that exceeds the threshold exists can be extracted as the object surface. You can do it. In addition, as shown in FIG. 3, in this embodiment, this operation is performed for all lines of sight that penetrate the object. That is, the three-dimensional scanner connected to the ultrasonic diagnostic apparatus 11 collects three-dimensional echo data from the target in the living body, then sets the viewpoint position of the observer, and then the surface position of the target seen by the observer. All information (x, y, z coordinate values) is automatically calculated by the threshold method. In this embodiment, a three-dimensional workstation using the Z buffer method is used, and the calculated surface information is this Z
It is designed to be saved in the buffer memory.

Following the calculation and storage of the surface information as described above, the normal vector is calculated. That is, as shown in FIG. 4, first, four adjacent points (P _{k, j} ,
The surface position information of P _{k, j−1} , P _{k + 1, j} , P _{k + 1, j−1} ) is read from the three-dimensional data memory 21, and the normal vector Nk of the minute plane passing through these four points is Is calculated. And
Since this is performed at any time while scanning in the x direction, all normal vectors of the object are automatically calculated.

When all normal vectors of the object are automatically calculated, the normal vector components are collected in the normal vector component memory unit 29. Then, all the automatically calculated normal vectors and phon shading parameters of the object are set, and finally, the von shading method is used to determine the brightness from the position of the light source, the position of the observer, and the normal vector. It comes to be assigned to each minute plane.

The von shading method by the three-dimensional display method, which is often used in the field of computer graphics, uses the software for executing the contents shown in the equations in FIG. 5 in the embodiment. Done. By the way, FIG. 6 shows variables and vectors in each expression in FIG.

Further, the remarkable effect of this embodiment is as shown in the photograph shown in FIG. The photograph of FIG. 7 shows the diagnosis result of bladder cancer, and the photograph 1 is the conventional one and the photograph 2 is the one displayed by the ultrasonic three-dimensional image display device in the present embodiment. As is clear from the comparison of these photographs, the one displayed by the ultrasonic three-dimensional image display apparatus in this example is designed to display the details of the unevenness of the surface of the tissue, etc. It can be seen that the site and the cancer site can be clearly distinguished.

[0022]

As described above, in the three-dimensional image display device according to the present invention, the parameters of the von shading method are created based on the surface extraction by the threshold method, and the brightness is adjusted based on the parameters. Since it is decided, it is possible to automatically perform surface extraction, which was conventionally done manually, and it is also possible to perform precise display, so that automation of operation and improvement of measurement accuracy can be achieved at the same time. It has a remarkable effect that

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a three-dimensional image display device according to an embodiment.

FIG. 2 is a flowchart showing a flow of operations of this embodiment.

FIG. 3 is an explanatory diagram illustrating a mechanism of surface extraction in the present embodiment.

FIG. 4 is a diagram showing how a normal vector is calculated in this embodiment.

FIG. 5 is a diagram showing calculation formulas and the like when calculating luminance by the von shading method.

FIG. 6 is an explanatory diagram showing variables and vectors in each expression in FIG.

FIG. 7 is a photograph showing the effect of the three-dimensional image display apparatus according to the present embodiment, showing the result of bladder cancer diagnosis in comparison with the conventional apparatus.

FIG. 8 is an explanatory diagram illustrating surface extraction by a threshold method.

FIG. 9 is an explanatory diagram illustrating a state of three-dimensional construction by the von shading method.

[Explanation of symbols]

 11 Ultrasonic Diagnostic Device 19 Phone Shading Parameter Setting Section 21 Three-Dimensional Data Memory Section 25 Surface Position Information Memory Section 27 Surface Position Detection Section 29 Normal Vector Component Memory Section

Claims (1)

Claim: What is claimed is: 1. An ultrasonic three-dimensional image display device for three-dimensionally displaying three-dimensional ultrasonic echo information obtained from the inside of a living body, wherein the surface position of an object is thresholded. And the surface position extracting means for extracting the surface position of the object based on the position information of the surface of the object extracted by the surface position extracting means. A normal vector calculating means for calculating a line vector, and a brightness calculating means for calculating the brightness of the surface of the object by the von shading method from the normal vector calculated by the normal vector calculating means and the positions of the viewpoint and the light source. And an ultrasonic three-dimensional image display device having.