JP2000285261A - Three-dimensional visualizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a three-dimensional visualizing device which easily calculates the volume of an visualization object. SOLUTION: Mask information indicating whether the occupation area of each of voxels constituting a view volume 50 should be taken as a visualization object or not is set by user's operation or the like and is stored in a mask memory. Thereafter, the number of voxels whose occupation areas are indicated as the visualization objects by mask information is counted, and the volume occupied by the whole of visualization objects is calculated on the basis of the counted result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional visualization apparatus, and more particularly to a technique for calculating the volume of a visualized object.

[0002]

2. Description of the Related Art There is a technique called a ray casting method as one of methods of volume rendering by CG. In this technique, first, a target object constituted by voxels is arranged in a virtual three-dimensional space defined in a memory space. Each voxel is given internal information of the target object as a plurality of voxel values. Then, a plurality of unit rays are virtually emitted from a viewpoint arranged at a predetermined position in the virtual three-dimensional space, and each pixel on the display plane is determined based on the voxel value of the voxel arranged on each unit ray. A value is calculated.

According to the ray casting method, various internal information of a target object can be freely visualized according to the purpose. Therefore, as a new visualization technique (volume visualization) of a three-dimensional object including a living body. In recent years, it has attracted attention.

[0004]

In this technique, the area occupied by the target object in the virtual three-dimensional space and the other area cannot be distinguished by voxel values.
It is difficult to automate this. Therefore, virtual 3
It was not always easy to specify the area occupied by the object to be visualized in the dimensional space and determine its volume.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a three-dimensional visualization device capable of easily calculating a volume of a visualization target.

[0006]

In order to solve the above-mentioned problems, a three-dimensional visualization apparatus according to the present invention, corresponding to each voxel constituting a virtual three-dimensional space, sets an occupied area of the voxel as a visualization target. Mask information storage means for storing mask information indicating whether or not to perform the counting, counting means for counting the number of voxels represented by the mask information indicating that the occupied area is to be visualized, and counting results by the counting means And a volume calculating means for calculating a volume occupied by the entire visualization target based on. Here, the mask information is set, for example, by a user operation.

According to the present invention, for a voxel in which mask information is set as a visualization target by a user operation or the like,
The number is counted, and the volume occupied by the entire visualization target is calculated based on the counting result. This makes it possible to easily calculate the volume of the visualization target. In particular, the volume of the object to be visualized can be easily calculated by setting the mask information so that the occupied area of all the voxels constituting the object to be visualized is the object to be visualized and exclude the other voxels from the object to be visualized. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a three-dimensional visualization device according to an embodiment of the present invention. The three-dimensional visualization device 10 shown in FIG. 1 includes a view volume memory 12, a mask memory 14, a mask generation surface calculation unit 16, a memory control unit 18, a mask bit counter 20, a tilt calculation unit 22, a luminance calculation unit Unit 24 and synthesis result accumulation memory 26
, A synthesis calculation unit 28, a coordinate conversion unit 30, and a screen display memory 32.

The three-dimensional visualization device 10 visualizes a 3D object arranged in a virtual three-dimensional space (view volume) in a mode according to the purpose. The view volume and the 3D object are configured by a three-dimensional array of voxels. Is done. The view volume memory 12 is a memory for storing voxel information given to voxels constituting a view volume or a 3D object.
It is composed of AM or ROM. The voxel information includes various measured data (voxel values) and opacity and color information corresponding to the measured data. For example, when the three-dimensional visualization device 10 is applied to a medical image processing device, CT values and MR values measured by an X-ray CT device are used.
The T value or the like measured by the I device can be adopted as the voxel value.

FIG. 2 shows the view volume memory 12.
FIG. 3 is a diagram showing a view volume in which voxel information is stored. As shown in the figure, the 3D object 44 to be visualized is arranged in the view volume 40.
This view volume 40 is configured by a three-dimensional array of voxels 41. The voxel information is X-ray CT
In the case where a measurement value obtained by the apparatus is used, many impurities 42 may be included in addition to the 3D object 44 to be visualized. Therefore, the view volume memory 1
If the visualized image is synthesized and displayed based on the voxel information relating to all the voxels stored in 2, as shown in FIG. 3 (a), many contaminants 42 will be present in addition to the 3D object 44 originally planned as the visualization target. Will be displayed. This makes it difficult to observe the 3D object 44. In the three-dimensional visualization device 10, these contaminants 42 are removed in the course of the visualization process, and only the 3D object 44 that is originally scheduled to be visualized is displayed as shown in FIG.

More specifically, in the present three-dimensional visualization apparatus 10, a mask memory 14 is provided corresponding to the view volume memory 12, and mask information corresponding to each voxel constituting the view volume 40 is stored. I have. This mask information is 1-bit information having either a valid or invalid value. When the mask information is valid, it means that the corresponding voxel is to be visualized. When the mask information is invalid, the corresponding voxel is visualized. It means to exclude from the target.

By storing this mask information in the mask memory 14, only the area required by the user can be visualized. However, we determine whether each voxel constitutes the target object,
If you set valid or invalid for the corresponding mask information,
It is a huge task. Therefore, in the three-dimensional visualization apparatus 10, as shown in FIG. 2 or FIG. 4, a mask generation plane 46 which is an arbitrary plane is set in the view volume 40, and voxels located inside or outside the plane are set as boundaries. , Mask information indicating invalidity can be set at once. In the figure, a circle indicates a voxel to which mask information indicating validity is added, and a mark indicates a voxel to which mask information indicating invalidity is added. Also, mask generation surface 4
Reference numeral 6 is set by a user using an operation unit (not shown) provided in the mask generation surface calculation unit 16.

[0014] Then, 3
D object 44 and impurities 42 are separated, and impurities 4
The mask generation surface 46 is arranged so that the mask information indicating invalidity is set in 2. The number of impurities 42 is not limited to one,
In addition, since there is a case where the object exists so as to surround the 3D object 44, it is often not possible to remove all the contaminants 42 from the visualization target only by arranging one mask generation surface 46. For this reason, the mask information using the mask generation surface 46 is set in a direction to increase the mask information indicating invalidity. That is, even for a voxel that is validated by the processing of one mask generation surface 46, mask information indicating that the voxel has been invalidated is maintained as it is. On the other hand, even if a voxel is associated with voxel information indicating validity, if the voxel is subsequently invalidated by another mask generation surface 46, mask information indicating invalidity is set for the voxel. You. By repeating the setting of the mask generating surface 46 and the setting of the mask information based on the mask generating surface 46 a plurality of times in this manner, FIG.
As shown in (b), even if mask information to the effect is initially set for all voxels constituting the view volume 40, the 3D object 44 to be visualized is surrounded as shown in FIG. Mask information indicating invalidity can be set for all voxels, and conversely, mask information indicating validity can be set for voxels constituting the 3D object 44 to be visualized. In the figure, a heart figure is a 3D object 44
Represents the outline of.

Referring back to FIG. 1, the mask generation plane calculation unit 16 has a user interface for setting the mask generation plane 46, and the user can use the user interface to set the mask generation plane 46.
Can be specified. This designation can be performed, for example, by designating one point on the space and the direction of the normal line, or by designating the intercept for each coordinate axis. Then, the mask generation surface calculation unit 16 can read the mask information from the mask memory 14 via the memory control unit 18, and based on the mask information and the mask generation surface 46 set by the user, The mask information stored in the mask memory 14 is updated.

The tilt calculator 22 stores the view volume 40 from the view volume memory via the memory controller 18.
The voxel information is read out for all the voxels within, and the mask information corresponding to each voxel information is read out from the mask memory 14. Then, the voxel information and the mask information are transferred to the luminance calculation unit 24 at the subsequent stage, and a normal vector is calculated for each voxel, which is also sent to the luminance calculation unit 24 at the subsequent stage. The light source position and the viewpoint position are set in the luminance calculator 24, and the luminance of each voxel is calculated based on the information and the normal vector calculated in the preceding stage. At this time, the voxel for which mask information indicating invalidity is set is forcibly set to zero in luminance. For this reason, these voxels will not be reflected in the visualized image.

Thereafter, the brightness calculation unit 24 calculates the brightness of each calculation path based on the brightness of voxels on the calculation path. The synthesis calculation unit 28 is connected to a synthesis result storage memory 26, in which the synthesis results obtained by the synthesis calculation unit 28 are stored. Then, the synthesis calculation unit 28 performs the synthesis calculation based on the output of the luminance calculation unit 24 and the contents of the synthesis result accumulation memory 26 specified by the synthesis trajectory control by the memory control unit 18.

That is, for each operation path extending radially (in the case of the perspective projection method) from the viewpoint, they are subjected to the synthesis processing in parallel. The voxel to be processed forms a surface at each point in time, and the surface sequentially advances in a direction away from the viewpoint. Therefore, the synthesis result storage memory 2
Reference numeral 6 sequentially stores one surface of the calculation result of the synthesis calculation unit 28. Then, the synthesis calculation unit 28 performs synthesis calculation for each voxel on one surface to be processed with the next voxel along the operation path. Note that if all the calculations for one surface are performed in parallel, the amount of calculation becomes enormous, and the hardware resources become enormous. Therefore, the processing may be repeated for each of a predetermined number of calculation paths to perform processing for one surface.

The coordinate conversion unit 30 projects these calculation paths on a predetermined plane, and generates image information based on the luminance of each calculation path. The screen display memory 32 is a memory for storing the image information calculated by the coordinate conversion unit 30 in this manner. An image synthesizing unit and an image display unit (not shown) are connected to the subsequent stage of the screen display memory 32, and the image information stored in the screen display memory 32 is read out by the image synthesizing unit and is read by an LCD, a cathode ray tube or the like. It is displayed on the configured image display unit.

On the other hand, the mask bit counter 20 counts the number of mask information indicating validity. FIG. 6 shows a configuration example of the mask bit counter 20. As shown in FIG.
Are the conversion ROM 34, the adder 38, and the accumulation register 3.
6, and the stored contents of the mask memory 14 are read out, for example, by 8 bits at a time by the memory control unit 18, and are input to the conversion ROM 34. In the conversion ROM 34, 0 to 8 correspond to the number of high-level signals among the input 8-bit signals.
8 is output. Here, the mask memory 14
The bits stored at a high level are mask information indicating validity, and the bits stored at a low level are mask information indicating invalidity. Conversion R
The output of the OM 34 is input to the adder 38. The accumulation register 36 is reset to zero at the start of counting by initialization, and the output of the adder 38 is taken into the accumulation register 36 at the rising timing of the counter clock. Then, the stored contents are output to the outside and returned to the input of the adder 38. In this way, when the entire mask memory 14 is read, the number of pieces of mask information indicating validity is stored in the accumulation register 36. An external device (not shown) fetches the output of the accumulation register 36 at the end of the reading, multiplies it by a predetermined coefficient, and displays the result as a visualization target volume on a display. As described above, the impurities 42
When the mask information is set so as to exclude all of the voxels from the visualization processing, only the voxel information relating to the voxels constituting the 3D object 44 is effective. For this reason, the volume of the 3D object 44 can be measured by counting the number of voxels to which the voxel information indicating the validity is given.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a three-dimensional visualization device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a view volume.

FIG. 3 is a diagram showing a visualized image including a 3D object to be visualized and a plurality of impurities.

FIG. 4 is a diagram illustrating a method for setting mask information.

FIG. 5 is a diagram showing a setting example of mask information.

FIG. 6 is a diagram showing a configuration of a mask bit counter.

[Explanation of symbols]

10 three-dimensional visualization device, 12 view volume memory, 14 mask memory, 16 mask generation plane calculation unit,
18 memory control unit, 20 mask bit counter, 2
2 inclination calculator, 24 brightness calculator, 26 synthesis result storage memory, 28 synthesis calculator, 30 coordinate converter, 32
Screen display memory, 34 conversion ROM, 36 accumulation register, 38 adder, 40 view volume, 41
Voxels, 42 impurities, 44 3D objects, 4
6 Mask generation surface.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shoji Ishikawa 5-1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd. (72) Koji Kashite 5-1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio (72) Inventor Shunji Mimura 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo F-term in Japan Radio Co., Ltd. (reference) 5B050 BA07 CA07 EA03 FA02 5B080 AA17 FA06 GA01

Claims (2)

[Claims] 1. Mask information storage means for storing, for each voxel constituting a virtual three-dimensional space, mask information indicating whether or not an occupied area of the voxel is to be visualized, an occupied area to be visualized Counting means for counting the number of voxels represented by the mask information, and volume calculating means for calculating the volume occupied by the entire visualization target based on the counting result by the counting means. 3D visualization device. 2. The three-dimensional visualization device according to claim 1, wherein the mask information is set by a user operation.