JP4272415B2 - 3D image display method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional image display by a central projection method for a group of image data obtained by stacking a plurality of tomographic images, and a three-dimensional image display method for displaying a viewpoint position and a line-of-sight direction for performing the central projection on a cut surface image. About.
[0002]
[Prior art]
In order to give a sense of perspective or to give a three-dimensional reality, a three-dimensional image is a stack of multiple tomographic images (two-dimensional images) such as X-ray CT tomographic images and MRI tomographic images (hereinafter referred to as This is an image created by looking at the stacked image from a certain viewpoint or light source and giving a perspective or shadow.
[0003]
A 3D image is an artificially created image, not a stacked image itself. For example, a method called volume rendering is a method in which reflection and transmission calculations of light from a light source are performed based on the positional relationship between viewpoints, light sources, and volume data (objects), and the reflected light from an object is projected onto a projection plane representing a field of view. It is.
[0004]
Further, by obtaining the pixel value of each tomographic image, there is a method called MPR (M ulti P lanner R econstruction ) image display to create a cutting plane image at an arbitrary position.
[0005]
The volume rendering described above includes the following two methods depending on the projection method.
One is a method called a parallel projection method that performs reflection and transmission calculations of light along parallel scanning rays, assuming that the viewpoint position is at infinity with respect to the volume data. The other is referred to as a central projection method in which an arbitrary viewpoint position is set and light reflection / transmission calculation is performed along scanning rays radially emitted from the viewpoint position, as described in [Patent Document 1]. It is a technique.
[0006]
[Patent Document 1]
JP 7-210704 A [0007]
Volume rendering by the central projection method (hereinafter simply referred to as the central projection method) can change the viewpoint position, and by setting the viewpoint within the observation object, it is possible to obtain an image that cannot be observed from outside the object. .
[0008]
However, from the image of the central projection method, it is difficult to determine the viewpoint position and the line-of-sight direction which are the display conditions of the image. Therefore, when displaying the center projection image, a method of displaying the viewpoint position and the line-of-sight direction of the center projection method image using the MPR cut surface image as an auxiliary image is often used. In addition, the information indicating the viewpoint position and the line-of-sight direction is operated on the image, and the viewpoint position and the line-of-sight direction are set.
[0009]
[Problems to be solved by the invention]
However, in the above prior art, when displaying a three-dimensional image by the central projection method, the central projection image and the MPR cut surface image including information indicating the viewpoint position and the line-of-sight direction are displayed at the same time. There has been no consideration for displaying a cut surface image depending on the positional relationship between the inside and the outside of the target volume data.
[0010]
In addition, since the MPR cut plane image display was displayed at a constant magnification regardless of the viewpoint position, it was difficult to check the viewpoint position and line-of-sight direction when the viewpoint was moved from inside the object to outside the object or from outside the object to inside the object. There was a problem that there was.
[0011]
An object of the present invention is to provide a three-dimensional image display method capable of displaying a positional relationship between a viewpoint position and volume data inside and outside.
[0012]
[Means for Solving the Problems]
An object of the present invention is to provide a three-dimensional image display method for generating and displaying a pseudo three-dimensional image by a central projection method based on a set viewpoint position and line-of-sight direction from three-dimensional image data. This is achieved by displaying information representing at least one of the directions together with the pseudo three-dimensional image.
[0013]
Preferably, information representing the viewpoint position and the line-of-sight direction is displayed on a cut surface image representing a cross section including the viewpoint position obtained from the three-dimensional image data. As an example, information indicating the viewpoint position and the line-of-sight direction is displayed on each of the cut surface images representing three orthogonal cross sections including the viewpoint position obtained from the three-dimensional image data.
[0014]
Preferably, when the viewpoint position is located in the three-dimensional image data, the viewpoint position and the line-of-sight direction are displayed in the cut surface image. Alternatively, when the viewpoint position is located outside the three-dimensional image data, the viewpoint position and the line-of-sight direction are displayed outside the cut surface image.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment according to the present invention will be described with reference to the drawings.
Fig. 1 shows the positional relationship between the viewpoint position and the MPR cut surface image when the viewpoint position is inside (b) and outside (b) of the image data group (hereinafter referred to as volume data 1) in which tomographic images are stacked. .
[0016]
As shown in FIG. 1A, the MPR cut surface image of the volume data 1 including the viewpoint position is displayed. Note that the cut surface image processing method is general MPR image processing, and therefore the description of the processing is omitted here.
The MPR cut surface images to be displayed are defined by the coordinate system 7 assuming that they are orthogonal to each other.
These are composed of an MPR cut plane image 2 relating to the XY plane including the viewpoint position 5, an MPR cut plane image 3 relating to the YZ plane including the viewpoint position 5, and an MPR cut plane image 4 relating to the ZX plane including the viewpoint position 5. A line-of-sight arrow 6 indicates a line-of-sight direction.
[0017]
FIG. 2 is a diagram for explaining a display method of the line-of-sight arrow 6 on the MPR cut surface images 2 to 4. The line-of-sight arrow 6 is a three-dimensional vector. The line of sight 10 obtained by projecting the line-of-sight arrow 6 onto the three MPR cross sections orthogonal to each other is displayed as a line of sight on each MPR cut surface image.
[0018]
FIG. 3 shows the screen image display state when the viewpoint position is in the volume data 1 when the MPR cut surface image, the viewpoint position, and the line-of-sight direction are defined as described above.
[0019]
As shown in FIG. 3, a section plane image 2 about the XY plane including the three-dimensional image 14 and the viewpoint position 5 by the central projection method, a section plane image 3 regarding the YZ plane including the viewpoint position 5, and a ZX including the viewpoint position 5 A section plane image 4 relating to a plane and the respective line-of-sight direction vectors 11 to 13 are displayed.
[0020]
Next, in the case of being outside the volume data 1 shown in FIG. 1B, the entire volume space 8 including the viewpoint and the volume data 1 is converted into each MPR cut surface image and MPR cut surface image in the same manner as described above. Find the projected line-of-sight vector. FIG. 4 shows an image display state of the screen when the viewpoint position is outside the volume data 1.
[0021]
As shown in FIG. 4, the three-dimensional image 14 by the central projection method, the cutting plane image 2 regarding the XY plane including the viewpoint position 5 and the volume data, and the cutting plane image 3 regarding the YZ plane including the viewpoint position 5 and the volume data, Then, the cutting plane image 4 relating to the ZX plane including the viewpoint position 5 and the volume data, and the respective line-of-sight direction vectors 11 to 13 are displayed.
[0022]
When the viewpoint position is changed, the positional relationship between the viewpoint position and the volume data 1 is determined as follows, and the display screens in FIGS. 3 and 4 are switched.
[0023]
The center of volume data 1 is the origin (x = 0, y = 0, z = 0). When the volume data 1 is a rectangular parallelepiped having the length of each side (x = k, y = l, z = m), the inside of the volume data can be expressed by [Expression 1].
[Formula 1]
-2 / k ≪ x ≪2 / k
-2 / l ≪ y ≪2 / l
-2 / m ≪ z ≪2 / m
[0024]
When the viewpoint position P is expressed by (Xe, Ye, Ze), and the viewpoint position is outside the volume data 1, the condition of [Equation 1] is not satisfied. By evaluating the condition of this expression 1, it is possible to determine, and by displaying a display screen that matches each condition, the state of the cut surface image including the viewpoint position and the line-of-sight direction is automatically switched, and The center projection image is displayed.
[0025]
FIG. 5 is a block diagram showing a hardware configuration example to which the method of the present invention can be applied. In FIG. 5, 50 is a CPU, 51 is a main memory, 52 is a magnetic disk, 53 is a display memory, 55 is a mouse controller, and these are connected to a common bus 57. The magnetic disk 52 stores a plurality of tomographic images and programs for coordinate conversion and shading. The CPU 50 reads the plurality of tomographic images and a program for coordinate transformation and shading, and uses the main memory 51 to construct a three-dimensional image as if the inside of the object is viewed with an endoscope, The data is sent to the display memory 53 and displayed on the CRT monitor 54. A mouse 56 connected to the mouse controller 55 designates a viewpoint position and the like when forming a three-dimensional image. The obtained three-dimensional image is stored in the magnetic disk 52 as necessary.
[0026]
The viewpoint position moving operation method is performed by a pointing device such as a mouse or a numerical value setting. The viewpoint position is evaluated by software. Processing for inputting these viewpoint positions and corresponding to the input values is performed in the conventional central projection image creation processing.
[0027]
As described above, according to the present embodiment, in the cut plane display including the three-dimensional image by the central projection method and the viewpoint position, and the gaze direction display, the cut plane always includes the viewpoint position on the inner side and the outer side of the volume data. Since the image can be displayed, the relationship between the central projection image and the viewpoint position can be easily understood.
[0028]
It also determines whether the viewpoint position is inside or outside the volume data, automatically switches the display state of the cut surface image including the viewpoint position and the line-of-sight direction, and displays the central projection image, so that the viewpoint position is displayed. Setting operation is not required.
[0029]
【The invention's effect】
The present invention has an effect of providing a three-dimensional image display method capable of displaying a positional relationship between a viewpoint position and volume data.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the relationship among MPR cut surface images, viewpoint positions, and line-of-sight directions when the viewpoint position is inside (b) and outside (b) the volume data.
FIG. 2 is a diagram for explaining a state in which a line of sight at the time of creating a three-dimensional image by the center projection method is projected onto each MPR cut surface.
FIG. 3 is a diagram showing an example of a screen image display when the viewpoint position is inside the volume data.
FIG. 4 is a diagram illustrating an image display example of a screen when the viewpoint position is outside the volume data.
FIG. 5 is a block diagram showing a hardware configuration example to which the method of the present invention can be applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Volume data 2 MPR image about XY plane 3 MPR image about YZ plane 4 MPR image about ZX plane 5 Viewpoint position 6 Arrows representing gaze direction vector 7 Three-dimensional coordinate system orthogonal to each other 8 Total volume space 9 including viewpoint and volume data Each MPR cut surface image 10 Line of sight on MPR plane (Projection of line of sight onto MPR plane)
11 Gaze Vector Displayed on MPR Image Related to YZ Plane 12 Gaze Vector Displayed on MPR Image Related to XY Plane 13 Gaze Vector Displayed on MPR Image Related to ZX Plane 3 Three-dimensional Image 50 CPU by Center Projection Method
51 Main memory 52 Magnetic disk 53 Display memory 54 CRT
55 Mouse controller 56 Mouse 57 Common bus

Claims (2)

An image processing apparatus including a calculation unit and a display unit is an operation method for displaying a three-dimensional image formed by stacking a plurality of medical tomographic images , and the set viewpoint position and line of sight are set from the three-dimensional image data. A cross section including the viewpoint position obtained from the three-dimensional image data, the information representing the viewpoint position and the line-of-sight direction when generating and displaying a pseudo three-dimensional image by the central projection method based on the direction. In a three-dimensional image display method for displaying together with a cut surface image representing
When the viewpoint position is located in the 3D image data, the viewpoint position and the line-of-sight direction are displayed in the cut plane image, and when the viewpoint position is located outside the 3D image data, the cut plane is displayed. A three-dimensional image display method, wherein the display of the viewpoint position and the line-of-sight direction in the cut surface image is changed so that the viewpoint position and the line-of-sight direction are displayed outside the image. The three-dimensional image display method according to claim 1,
The information representing the viewpoint position and the line-of-sight direction is displayed on each of the cut surface images representing three orthogonal cross sections including the viewpoint position obtained from the three-dimensional image data. .

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