JP2002352264A - Method and device for creating pattern image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for creating pattern image capable of creating a pattern image to which an endless processing is applied by expressing a depth of field effect by using orthogonal projection and creating the pattern image with distinctive design. SOLUTION: A visual line angle θ, an angle to incline visual lines in the case of projecting a fragment as an object polygon, is calculated (S11) after mapping a set image to the fragment and visual line vectors (Vx, Vy) in a screen plane to determine the direction to incline the visual line angle θ are calculated (S12). Next, rendering is performed by using technique of the orthogonal projection (S14) after performing coordinate conversion (S13) based on the calculated visual line angle θ and the visual line vectors (Vx, Vy) for speedup of an arithmetic processing. Then, an average by rendering results performed so far is calculated and recorded by using this rendering result (S15). A projection image having patterns is obtained by repeating processings from S11 to S15 for the set number of visual line angles (S16).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for creating an image by projecting an object represented in a three-dimensional space onto a two-dimensional plane, and more particularly to a technique for making a pattern such as artificial marble using such a technique. The present invention relates to a pattern image creation method and apparatus for artificially creating a pattern image.

[0002]

2. Description of the Related Art Conventionally, various patterns have been used to decorate the surface of building material products. Among them, the artificial marble pattern has a sense of quality and is very popular. In order to create such an artificial marble pattern, it is necessary to directly shoot a real artificial marble, but the production cost is high and there are no variations. . Recently, attempts have been made to artificially generate a marble pattern using computer graphics, but it has been difficult to obtain something close to the real thing.

In general, the pattern of artificial marble is such that a medium contains other objects such as pebbles. Since only this surface can be seen from the outside, it is considered that an artificial marble pattern can be approximated by an image obtained by projecting an object such as a pebble on the surface. Therefore,
2. Description of the Related Art A technique for projecting an object in a three-dimensional space, that is, a technique for expressing three-dimensional CG (computer graphics) has been used.

Here, a description will be given of a three-dimensional CG expression technique. In the three-dimensional CG expression technology, a projection method is used in consideration of the depth-of-field effect of an object existing in a three-dimensional space in order to express a more three-dimensional effect.
The depth of field is the distance from the plane on which the viewpoint is in focus, and the depth of field effect is the three-dimensional space of objects other than the depth of field. This is a method of giving a sense of realism by applying a blur according to the difference between the images.

[0005] Such a method of performing rendering utilizing the depth of field effect is generally realized by using a perspective radiation shadow. Here, rendering using perspective radiation shadows will be described. FIG. 11 is a diagram showing a relationship among an object, a focal plane, and a viewpoint when performing perspective radiographic projection. As shown in FIG. 11A, a predetermined angle of view is set for the viewpoint, and objects included in the range of the angle of view are projected to the viewpoint. In FIG. 11A, the focal plane and the viewpoint appear to form a triangle. However, since it is actually a three-dimensional space, a cone or a pyramid having the focal plane as the bottom and the viewpoint as the apex is formed. It is a constituent relationship. The perspective radiation shadow is a method of reflecting the color information at each point on a plane which is circular or polygonal and parallel to the focal plane on the viewpoint. By applying this viewpoint to each pixel position, a projected image can be obtained.

As described above, a projected image can be obtained by performing a perspective radiation shadow on each pixel. Actually, in order to improve the accuracy, FIG.
As shown in (c), a projection image in a state where the viewpoint position is changed (jitter processing) is obtained, and an average value of these projection images is obtained to obtain a final projection image. As the viewpoint position is increased, a more accurate projection image can be obtained. By utilizing such a three-dimensional CG expression technology, it is possible to easily create an artificial marble pattern.

[0007]

As described above, when rendering an image of a predetermined size to create a marble-patterned image, the technique of the perspective projection shadow with the jitter processing has a great effect. However, when creating a pattern image or the like, it is common to create a reference unit image and repeatedly arrange it in the up, down, left, and right directions to obtain a pattern image of a desired size. . When an image having a target size is created by repeating the unit images in this manner, it is preferable to perform endless processing so that the joints are not conspicuous.

However, in the case of generating an endless image in which the same picture appears repeatedly, the perspective radiation method uses a visual volume (a volume in a three-dimensional space that affects one point on a generated two-dimensional image). Since the objects are spread as shown in FIG. 12, even if the objects arranged in the three-dimensional space are endless, the edges (upper, lower, left and right) of the rendered image are not connected. Therefore, a preferable endless image cannot be obtained. Further, there is no unique pattern on the surface of the projected object, and the resulting artificial marble pattern is dull.

In view of the above points, the present invention makes it possible to create a pattern image subjected to endless processing by expressing a depth-of-field effect using orthographic projection, and at the same time to create an individual pattern image. It is an object of the present invention to provide a pattern image creation method and apparatus capable of creating a pattern image of a simple design.

[0010]

In order to solve the above-mentioned problems, in the present invention, necessary parameters are input, an image to be generated is input on the surface of the fragment, and the fragment is placed in a three-dimensional space based on the input parameters. After the image is pasted on the generated fragment, the fragment on which the image is pasted is projected onto a two-dimensional plane by an orthogonal projection method, and the pixel value projected in consideration of the transparency of the medium is calculated. A pattern image creating method, wherein a projected image is created by calculation. In the present invention, in particular, a projection image is obtained by projecting a fragment generated in a three-dimensional space onto a two-dimensional plane in consideration of the transparency of a medium by an orthogonal projection method. It is possible to create a pattern image with inconspicuous joints by repeatedly arranging as a unit image, and it is also possible to create an artificial marble tone pattern image having a unique design pattern on the surface of the fragment Become.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart of a pattern image creating method according to the present invention. First, parameters regarding how to generate fragments in a three-dimensional space are input (step S1). Such parameters include the projection area including the screen size and position, the number of texture groups, the surface texture, the size of the fragments (objects), the bottom shape of the fragments, the height of the vertices, the arrangement density, and the fragments in the projection region. Set the arrangement range of.
The projection area is a three-dimensional area for projecting the unit image by orthographic projection. Here, the size of the screen S, which becomes a unit image after projection, is assumed to be w pixels (x direction) × h pixels (y direction). Further, the z direction indicates the depth. FIG. 2A shows an example of such a projection area.
The number of texture groups indicates the number of types of texture on the fragment surface.
The size of the fragments, the bottom shape of the fragments, the height of the vertices, the arrangement density, and the arrangement range of the fragments in the projection area are set.

The surface texture is the texture of the generated fragment surface, and is set by designating a texture for mapping on the fragment surface. The specification of the texture is performed by specifying the ID or the like of a file storing the texture as an image.

The three parameters of the fragment size, fragment bottom shape, and vertex height are used to determine the fragment shape. Here, an example of the fragment shape is shown in FIG. FIG.
In the example shown in the figure, the parameter of the shape of the bottom surface of the fragment is set to a quadrangle. The size of the fragment is a parameter for setting the size of the bottom surface, and the height of the vertex is a parameter for setting the height of the vertex of the quadrangular pyramid from the bottom surface. In the case of the fragment shape as shown in FIG. 3, since the bottom surface is a quadrangle, it can be composed of at least two triangular polygons, and since the side surface is triangular, it can be composed of at least one triangular polygon. That is, the shape of the quadrangular pyramid shown in FIG.
It can be composed of three triangular polygons.

The arrangement range is a parameter for setting a range in which fragments are arranged in the projection area shown in FIG. This arrangement range is set by the z coordinate. FIG. 2B shows an arrangement range when the z coordinate is set to a predetermined range. In FIG. 2B, the inside of the shaded rectangular parallelepiped is the arrangement range. The arrangement density is a parameter for setting the density of the pieces arranged in the arrangement range.

Subsequently, parameters relating to how to perform a rendering process for projecting fragments in a three-dimensional space onto a two-dimensional plane are input (step S2). As such parameters, the arrangement position of the focal plane, the set number N of gaze directions, and the maximum gaze movement angle θ _max are set. Further, since the focal plane is arranged in parallel with the screen S, the arrangement position of the focal plane is set by the distance from the screen S. The set line-of-sight direction number N is a set number of line-of-sight directions for performing projection, and projection is performed from different directions by the set number to determine pixel values on the screen S. The line-of-sight movement maximum angle θ _max indicates the maximum angle at which the line-of-sight direction can be inclined when the line of sight and the screen S plane are perpendicular to 0 °.

Next, fragments are generated in a three-dimensional space (step S3). This means that pieces of the set shape are generated at the set density in the set arrangement area for each texture group. In addition, a specified texture image is mapped, that is, pasted, to each polygon constituting the generated fragment.

Here, a method of mapping a texture image will be described with reference to FIG. First, as a texture image, an image larger than a polygon constituting a generated fragment is prepared. In the example of FIG. 4, the texture image has a size of vertical IY × horizontal IX. First, for a certain polygon, one point A (x, y) is selected at random as shown in FIG. This is 0 ≦ x
This is performed by generating a random number in the range of ≦ IX, 0 ≦ y ≦ IY. FIG. 4B shows the relationship between the selected point A (x, y) and other vertices in the polygon.
As shown in the figure, the positional relationship between the points B and C on the texture image is determined. When both the points B and C fall within the texture image, the picture determined by the three points ABC is cut out and pasted on the polygon. As shown in FIG. 4 (c), when either point B or point C is out of the area of the texture image, the positioning of point A is performed again. The picture to be pasted on all the polygons generated as described above is determined.

Next, a medium polygon is generated (step S4). The medium polygon is generated at the same position as the screen S with the same size as the screen S. That is, since the screen S has a rectangular shape, it can be constituted by two triangular polygons. A medium texture prepared in advance can be attached to this medium polygon, but in the present embodiment, in order to make the medium uniform, the color is set to be uniform over the entire surface.

Next, the fragments are orthogonally projected onto the screen S, and the color of each pixel on the screen is determined (step S5). A plurality of line-of-sight directions for orthographic projection in step S5 are set, and a pixel value on the screen S is determined for each line-of-sight direction. The pixel values on the screen S obtained for each line-of-sight direction are finally averaged to obtain pixel values constituting one projection image. Here, first, the case where the line of sight from the screen S is perpendicular to the screen S will be described.

In this case, the pixel on a fragment is (x,
y) Projection is performed on a pixel on the screen S having the same coordinate value. At this time, the pixel value V _H of the pixel on the screen is calculated by the following (Equation 1).

(Equation 1) V _H = T × (D _O / D _F ) × V _O T: Attenuation rate

[0022] However, in the above (Equation 1), D _O is the distance from the screen S to the pixel V _O on the debris, D _F is the distance from the screen S to the focal plane. The above (Formula 1) indicates that the closer the pixel on the fragment is to the focal plane, the closer to the original pixel value, and the farther away from the focal plane, the more blurred. In addition, since the pieces are randomly arranged in the three-dimensional space, only pieces closest to the screen S are visible for pieces that overlap on the line of sight from the screen S. This can be expressed simply by comparing the z-coordinates of both fragments and utilizing the one close to the screen S.

Further, the pixel value on the screen S is not determined solely by this, but is also determined in consideration of the attenuation due to the medium. Let the pixel value of the medium be V _B ,
Assuming that the transmittance for the combination is α (where 0 ≦ α ≦ 1), the pixel value V on the screen S is shown below (Equation 2).
Is calculated by At this time, the pixel value on the medium polygon generated on the screen is adopted as the pixel value V _B of the medium.

(Equation 2) V = α × V _H + (1−α) × V _B

As can be seen from Equation (2), the larger the value of the transmittance α, the more the original color is expressed, and the smaller the value of the transmittance α, the stronger the effect of the medium color. Become.

When the line of sight is changed, projection is performed in the same manner. For example, when performing orthographic projection at the line-of-sight angle θ,
The line-of-sight angle θ is calculated by the following (Equation 3).

(Equation 3) θ = θ _max × γ ₁

In the above (Equation 3), θ _max indicates the maximum line-of-sight movement angle set in step S1, and γ
₁ indicates a random number generated to have a value in the range of 0.0 to 1.0.

Based on the line-of-sight angle θ, fragments on the screen S corresponding to the line-of-sight angle θ are obtained by orthogonally projecting fragments present in the three-dimensional space and considering the influence of the medium. Here, FIG. 5 shows the relationship between the line-of-sight angle θ, the screen S, and the pieces when focusing on a certain piece. In the figure, the horizontal axis is the z-axis shown in FIG.
FIG. 5A shows a state in which the viewing angle is 0 °, that is, the viewing direction is perpendicular to the screen S. FIG. 5 (b)
(C) shows a state in which the viewing direction is inclined by the viewing angle θ. Although the screen and the fragments shown in FIGS. 5A to 5C are all located at the same position, the appearance of the fragments projected on the screen differs due to different viewing angles. FIGS. 6 (a) to 6 (c) show the state of the fragments projected on the screens of FIGS. 5 (a) to 5 (c), respectively.
Shown in In FIG. 6A, the object is projected at the center of the screen, but in FIG. 6B, the object is projected below the screen, and in FIG. 6C, it is projected above the screen.

The orthographic projection in step S5 is performed for the set number of gaze directions set in step S2. That is, rendering results for the set number of gaze directions are obtained. The finally obtained projection image is an average of these rendering results. Here, details of the processing procedure in step S5 will be described based on the flowchart of FIG. First, the line-of-sight angle θ is calculated using (Equation 3) as described above (Step S)
11).

Subsequently, the line-of-sight vector (V) in the screen plane for determining the direction in which the line-of-sight angle θ is inclined is determined.
x, Vy) is calculated by the following (Equation 4) (step S12).

(Equation 4) Vx = sin φ Vy = cos φ where φ = 360 ° × γ ₂

In the above (Equation 4), γ ₂ is 0.0 to 0.0
Indicates a random number generated to be a value in the range of 1.0.
Thus, the line-of-sight angle θ and the line-of-sight vector (V
When x, Vy) is determined, the direction of the line of sight for performing the orthogonal projection is specified in one direction. Therefore, orthographic projection from the specified line of sight to the screen, that is, rendering to the screen, is performed. This is specifically performed using the above (Equation 1) and (Equation 2), but the line-of-sight direction θ = 0 °
In other cases, the calculation of the distance requires a position calculation at each of the three-dimensional coordinates, which increases the calculation load. Therefore, in the present invention, in order to reduce the calculation load, before performing the rendering processing, the position coordinates of the fragment are converted so that the distance can be calculated with one coordinate axis (step S13).

Specifically, since each fragment is composed of a polygon, the coordinate values of each vertex of this polygon are converted by the following (Equation 5) and (Equation 6).

(Equation 5) K = tanθ × abs (LZ)

The above (Equation 5) is for calculating the movement amount K, where L indicates the z coordinate value of the projection plane, Z indicates the z coordinate value of the polygon, and abs indicates the absolute value.

(Equation 6) Mx = Vx × K My = Vy × K

In the above (Equation 6), the movement amounts Mx and My of the x coordinate and the y coordinate are calculated using the movement amount K calculated in (Equation 5). As a result, the coordinate values (X, Y, Z) of the vertices of each polygon are calculated as the virtual coordinate values (X + M
x, Y + My, Z).

The coordinate conversion processing in step S13 is performed for each vertex of each polygon constituting each fragment. Thus, coordinate values in a virtual three-dimensional space are created. For example, when a polygon exists in a state as shown in FIG.
This is converted into the state shown in FIG. Thus, the vertex A (X,
Y, Z) will move to A '(X + Mx, Y + My, Z). By performing the conversion in this manner, the difference between the values in the z-axis direction (the horizontal direction in FIG. 8) becomes the distance to the projection plane as it is.

Subsequently, based on the virtual coordinate values,
By using (Equation 1) and (Equation 2), the pixel value V of the pixel on the screen S is calculated. At this time, the distance D _O and the distance D for calculating the pixel value V _H in (Equation 1)
_{Since it} is sufficient for _{F to} use only the z coordinate value in the virtual space, the calculation load is greatly reduced, and the processing can be performed at high speed. This set of pixel values is the rendering result in the case of the line-of-sight direction (step S14).

The result of rendering on the screen S is recorded in the image memory (step S15). in this case,
The first rendering result is written to the image memory as it is. The second and subsequent rendering results are added to a plurality of rendering results including the contents previously written in the image memory, and written as an average value up to that time. For example, the second rendering result is calculated by adding the first rendering result already stored in the image memory to each pixel and dividing by 2 to calculate an average value. Update the contents of the image memory. The third rendering result is calculated by doubling the rendering average up to the second rendering, adding each pixel, and dividing by 3 to calculate the average value up to the third rendering in the past, and rendering it up to the third rendering. Update the contents of the image memory as an average. When this is generalized, the rendering result of the n-th rendering is obtained by calculating the rendering average up to the (n-1) -th rendering by (n-
1) After adding the multiplied value for each pixel, the result is divided by n to calculate an average value up to the n-th time in the past, and update the content of the image memory as the rendering average up to the n-th time. That is, when the processing in step S15 ends, the average of the rendering results up to that point is always recorded in the image memory.

When the average value of the rendering result is recorded in step S15, steps S11 to S11 are executed.
It is determined whether the number of times the processing up to 15 has been performed has reached the set number N of gaze angles (step S16). If it has been executed N times, the process ends. If it has not been executed N times, the process returns to step S11 to continue the process. If YES is determined in the step S15, the previous rendering result recorded in the image memory is used as the projection image.

By the processing described with reference to the flowchart of FIG. 7, the processing of creating a projection image by orthographic projection in step S5 is executed. As a result, a desired projection image is obtained.

In the present invention, even when the size of the image memory for rendering is limited, a device is devised so that highly accurate rendering can be performed. Next, such a case will be described with reference to the flowchart of FIG.
First, the rendering range is divided (step S2).
1). This depends on the size of the unit image to be created,
Here, it is assumed that four divisions of 2 × 2 are performed. FIG.
When the size of the screen S is w pixels (x direction) × h pixels (y direction) as described in the example of (1), one rendering range is w / 2 pixels (x direction) × h / 2 pixels (y
Direction).

The subsequent steps S22 to S24 are performed for each of the divided rendering ranges. First, marking is performed on a fragment polygon completely included in one rendering range (step S2).
2). Furthermore, fragments included in this rendering range and other rendering ranges, that is,
Another marking is performed on the polygon of the debris on the boundary between the plurality of rendering ranges (step S23). This step S22, determination of whether acting on whether the boundary is included in the rendering range in step S23 is performed in consideration of the visual line movement maximum angle theta _max. That is, even if the line of sight is moved by the maximum line-of-sight angle θ _{max and} still included in the rendering range, marking is performed in step S22, and if the line of sight is moved by the maximum line-of-sight movement angle θ _{max, the} line of sight may fall outside the rendering range. In this case, marking is performed in step S23.

Subsequently, a process of creating a divided projection image is performed (step S24). FIG. 7 shows the specific processing.
The same processing as described in the flowchart of FIG. When one divided projection image is obtained, this image is stored in another storage area to make the image memory usable, and the process returns to step S22 to perform the same processing for another rendering range. However, the processing in step S24 is different for the second and subsequent rendering ranges. In the second and subsequent cases, processing is not performed again on polygons that have already been processed with respect to polygons of fragments that fall on rendering boundaries. Whether it has been already processed can be determined by the marking performed in step S23. As described above,
When the divided projection images are obtained for all the rendering ranges, the divided projection images are integrated to obtain a final projection image (step S25).

(Apparatus Configuration) Next, an apparatus configuration for executing the above-described pattern image creating method will be described. FIG.
1 is a configuration diagram of a pattern image creating device according to the present invention. In FIG. 10, a parameter input unit 1 is for executing steps S1 and S2 of FIG. 1, and can be realized by a mouse, a keyboard, or the like.

The fragment generating means 2 is for executing step S3 of FIG. 1 and has a function of arranging the fragments in the set three-dimensional space according to the parameters input from the parameter input means 1. The medium polygon generating means 3 is for executing step S4 in FIG. 1, and has a function of pasting a designated color or texture.

The projecting means 4 is for executing step S5 in FIG. 1 and projects the fragment subjected to the coordinate transformation processing of step S13 by the coordinate transformation means 5 to render the rendering result on the image memory 6. Has the function of repeatedly performing the projection process while writing. Each of the fragment generation means 2, medium polygon generation means 3, projection means 4, and coordinate conversion means 5 is actually realized by a computer and a dedicated program mounted on the computer, and the image memory 6 is mounted inside the computer. .

The output means 7 is for outputting a projection image obtained as a result of the processing by the projection means 4, and a display for displaying, an FD, an MO for outputting as image data, and the like can be applied.

[0051]

As described above, according to the present invention,
Enter the required parameters, enter the image to be generated on the surface of the fragment, generate fragments in 3D space based on the input parameters, paste the image on the generated fragment, and paste the image The projected fragments are projected onto a two-dimensional plane by an orthogonal projection method, and a projected image is created by calculating a pixel value to be projected in consideration of the transparency of the medium. It is possible to create a pattern image with inconspicuous joints by repeatedly arranging as a pattern, and it is also possible to create an artificial marble-like pattern image having a unique design pattern on the surface of the fragment Play.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a pattern image creating method according to the present invention.

FIG. 2 is a diagram showing a projection area set in a three-dimensional space.

FIG. 3 is a diagram showing an example of a fragment shape.

FIG. 4 is a diagram for explaining how to determine a picture to be mapped to a polygon;

FIG. 5 is a view angle, screen,
FIG. 4 is a diagram illustrating a relationship between objects.

FIG. 6 is a diagram showing a state where the relationship shown in FIG. 5 is viewed from a screen side.

FIG. 7 is a flowchart showing details of a process in step S5 of FIG. 1;

8 is a diagram for explaining the coordinate conversion process in step S13 in FIG.

FIG. 9 is a flowchart illustrating a process when the size of an image memory is limited.

FIG. 10 is a functional block diagram showing a configuration of a pattern image creating device according to the present invention.

FIG. 11 is a diagram showing a relationship among an angle of view, a focal plane, and an object when performing perspective radiographic shadowing.

FIG. 12 is a diagram illustrating a relationship among a viewpoint position, a rendering surface, and a viewing volume when performing perspective radiographic shadowing.

[Explanation of symbols]

 S ... Screen 1 ... Parameter input means 2 ... Fragment generation means 3 ... Medium polygon generation means 4 ... Projection means 5 ... Coordinate conversion means 6 ... Image memory 7 ... Output means

Claims (7)

[Claims] 1. A step of inputting necessary parameters; a step of inputting an image to be generated on a surface of a fragment; a step of generating a fragment in a three-dimensional space based on the input parameters; A step of pasting an image to the projection image by calculating the pixel value to be projected in consideration of the transparency of the medium while projecting the fragments on which the image is pasted onto a two-dimensional plane by an orthogonal projection method. A projecting image creating step of creating a pattern image creating method. 2. The method according to claim 1, wherein the step of generating a projection image includes determining a line-of-sight direction based on the input parameters, transforming coordinates of the generated fragments in a three-dimensional space based on the line-of-sight direction, and then performing orthogonal projection. 2. The pattern image creating method according to claim 1, wherein the projection is performed by a technique. 3. The coordinate transformation is performed by using the coordinates of a fragment in a three-dimensional space as a coordinate axis with a distance direction from a projection plane as a coordinate axis using a line-of-sight angle and a line-of-sight vector for determining the line-of-sight direction. 3. The method according to claim 2, wherein the coordinates are converted into coordinates. 4. The projection image creating step is to perform a plurality of renderings by changing a line-of-sight direction and calculate an average of rendering results obtained by each rendering to create a projection image. The pattern image creating method according to any one of claims 1 to 3, wherein: 5. Parameter input means for inputting necessary parameters and setting an image to be generated on the surface of the fragment.
A fragment generating means for generating fragments in a three-dimensional space based on the input parameters and attaching the set image to the generated fragments; determining a line-of-sight direction based on the input parameters; Coordinate transformation means for transforming the coordinates of the fragment in a three-dimensional space based on the pixel, and projecting the coordinate-transformed fragment on a two-dimensional plane by an orthogonal projection method and projecting the transparency in consideration of the medium. A pattern image creating apparatus comprising: a projecting unit that creates a projected image by calculating a value. 6. The coordinate conversion means converts the coordinates of the fragment in the three-dimensional space into a three-dimensional space having a distance direction from a projection plane as one coordinate axis using a line-of-sight angle and a line-of-sight vector for determining the line-of-sight direction. The pattern image creating apparatus according to claim 5, wherein the pattern image is converted into coordinates in (1). 7. The projection means includes an image memory for writing a rendering result, performs rendering a plurality of times by changing a line-of-sight direction, and stores a rendering result obtained by each rendering in a memory up to that time. 7. The pattern image creating apparatus according to claim 5, wherein a projected image is created by overwriting the image memory while taking an average value according to the number of writings.