JP2006039889A - Program for calculating direction of light source to picture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automate work for applying a shadow to an external wall by obtaining the position of a light source (sunlight) to a building. <P>SOLUTION: A program for calculating direction of the light source to a picture has: a face selection section selecting a face hit by light from the light source in a picture displayed on a computer screen; a portion selection section selecting a sunshine portion directly hit by the light generated from the light source and a shadow portion hit by no light in the selected face; a direction calculation section calculating the light source direction from brightness in the selected sunny portion and shadow portion; and a brightness calculation section calculating the brightness applied to the selected face based on the calculated direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  A program for reflecting a shadow on an outer wall in consideration of the direction of a light source that hits the outer wall of a building

  When trying to simulate the renovation of the outer wall of a house, the position of the light source in the photograph cannot be calculated in the past, so it is always realistic to assume the position of the light source and create shadows in photo processing etc. It was necessary to put out. However, it was difficult to automate the work, and it was always a manual work and was troublesome.

  For example, even if a new outer wall is attached to the outer wall of the photograph of FIG. 5 as shown in FIG. 6, the shadow is not taken into consideration and there is no sense of reality. Therefore, the presence of shadows increases as shown in FIG. 7, but it is very troublesome to manually specify individual shadows.

Japanese Patent Application Laid-Open No. 8-146484 discloses an invention that automatically sets shooting conditions by predicting the state of a shadow generated during shooting based on the incident direction of light from a light source and the intensity of light. Kaihei 10-74036 discloses an invention in which the appearance of a building to be repaired is photographed, the photographed data is processed by a computer, and the processed data is presented to a customer to proceed with exterior wall repair. However, there is no disclosure of a technique that adds a shadow to the outer wall to create a sense of reality.
JP-A-8-146484 JP-A-10-74036

  In view of the above points, the present invention aims at automating the work of shadowing the outer wall by determining the position of the light source (sunlight) that hits the building when simulating the reformation of the outer wall of the house.

  The first invention of the present application includes a surface selection unit that selects a surface that is exposed to light from a light source in an image displayed on a computer screen, and light from the light source that is directly applied to the selected surface. Based on the calculated direction, a partial selection unit that selects the shaded part that is not hitting and the shaded part that is not hitting, a direction calculation part that calculates the direction of the light source from the brightness in the selected sunny part and shaded part A brightness calculator for calculating the brightness reflected on the selected surface is provided.

  In a second aspect of the present invention, the direction calculation unit includes a processing unit that calculates the direction of the light source by designating two locations from the sunny portion and two locations from the shade portion.

  According to a third aspect of the present invention, when the direction θ is 0 ° or 90 °, the reflection processing unit adds a certain brightness to a surface that is irradiated with light from the light source, and is not applied to a surface that is not applied. If the brightness is reduced and θ is 45 °, the brightness is not corrected, and if θ is otherwise, a processing unit for adding or reducing the predetermined brightness is provided.

  Since there is no individual manual work as in the prior art, and the user only specifies the sun and shade, the renovated outer wall is shaded, which makes it easier to simulate the renovation of the outer wall of the house. Moreover, the calculation which adds a shadow can be easily performed only by designating two places in the sun and two places in the shade. In addition, it is possible to easily calculate the shadow according to the direction of any sun.

  FIG. 1 is a configuration diagram of an embodiment of the present invention. The surface selection unit 1 is a processing unit that stores a wall (surface) of a building selected by the user. The sun shade selection unit 2 allows the user to select a portion of the sun that hits the sun and a portion of the sun that does not hit the sun from the wall (surface) of the building selected by the face selection unit 1. A processing unit for storing. The direction calculation unit 3 is a processing unit that calculates the direction of the light source. The brightness calculation unit 4 is a processing unit that calculates the degree of brightness reflected on the wall (surface) selected based on the calculated direction. The degree of brightness refers to an amount that increases the brightness of a wall that is exposed to sunlight and an amount that decreases the brightness of a wall that is not exposed to sunlight. The reflection processing unit 5 is a processing unit that reflects the calculated brightness level on the selected wall (surface).

  This example will be described with reference to a flowchart (FIG. 4) taking the photograph of FIG. 2 as an example.

  When two orthogonal planes (here, plane A and plane B) of the building displayed on the computer screen are selected by the user, plane selection unit 1 stores the selected plane (S1).

  Next, when the sun parts p 'and q' which are shaded with the sun parts p and q where the sun hits the A and B faces are selected by the user, the sun part selecting unit 2 The color values of red R, green G, and blue B in the selected p, q, p ′, and q ′ are stored (S2) (FIG. 2).

Next, the direction calculation part 3 calculates a direction according to the following (S3). First, the selected sunny portion and shade portion are converted into a gray value I by the following equation.

The gray value of the shaded part on the A side and B side is almost the same, and the shaded shaded part is considered as a diffuse reflection component that affects the entire scene of the photo separately from the sunlight that is the light source, Subtract from the sunny part of the sun. Then, the solar light source direction is calculated from the difference between the subtracted values. That is, if the gray value at the p point is represented by Ip, the gray value at the q point is represented by Iq, the gray value at the p ′ point is represented by Ip ′, and the gray value at the q ′ point is represented by Iq ′, the light source direction θ is calculated by the following equation. The

  At this time, sunlight hits the B surface in FIG. 3 at an angle θ. On the other hand, sunlight hits the A surface at an angle of 90 ° −θ.

  Next, the brightness calculation unit 4 calculates the degree of brightness reflected on the A surface and the B surface based on the obtained light source direction θ according to the angle of the light source direction θ as follows ( S4).

  In the case of θ = 45 °, it is determined that the brightness is the same for both the A surface and the B surface, and the brightness level is not corrected.

  In the case of θ = 0 °, since sunlight hits the A plane vertically, a certain brightness (an arbitrary brightness degree S) is added to the A plane. A certain darkness (-S) is added to the B surface not exposed to sunlight.

  When θ = 90 °, since sunlight hits the B surface vertically, a certain brightness S is added to the B surface. A certain brightness (-S) is added to the A surface which is not exposed to sunlight.

In the case of θ <45 °, the A surface is more strongly exposed to sunlight than the B surface. At this time, the brightness level of the following equation is added to the A plane.

Moreover, the B surface is weaker than the A surface and is exposed to sunlight. At this time, the brightness level of the following equation is added to the B surface.

  In the case of θ> 45 °, the reverse of the case of θ <45 °.

  Finally, the reflection processing unit 5 reflects the calculated brightness degree S on the A side and the B side.

  In the present embodiment, the case where sunlight hits the wall of the building has been described. However, not only the building but also an object such as arbitrary furniture may be in a state where sunlight or light from an arbitrary light source is applied.

(Appendix 1) Computer
A surface selection unit that selects a surface that is exposed to light from a light source in an image displayed on a computer screen;
A partial selection unit that selects a sun part that is directly hit by the light from the light source and a shadow part that is not hit in the selected surface;
A direction calculation unit for calculating the direction of the light source from the brightness in the selected sun part and shadow part,
A brightness calculator that calculates the brightness reflected on the selected surface based on the calculated direction;
Reflection processing unit that reflects the calculated brightness on the selected surface,
Light source calculation program to function as. (1)
(Additional remark 2) The light source calculation program of Additional remark 1 which makes the said direction calculation part function further as a process part which designates two places from the said sun part, and two places from the said shadow part, and calculates the direction of a light source. (2)
(Supplementary Note 3) The direction calculation unit is a processing unit that designates two locations Ip and Iq from the sunny portion and two locations Ip ′ and Iq ′ from the shade portion and calculates the direction θ of the light source by the following equation The light source calculation program according to appendix 2, which further functions.
tan θ = (Iq−Iq ′) / (Ip−Ip ′)
(Supplementary Note 4) When the direction θ is 0 ° or 90 °, the reflection processing unit adds a certain brightness to the surface on which the light from the light source is applied, and applies the brightness to the surface on which the light is not applied. The light source calculation program according to appendix 1, 2, or 3, wherein the brightness is not corrected when θ is 45 °, and is further functioned as a processing unit for adding or subtracting the predetermined brightness when θ is otherwise . (3)
(Additional remark 5) The light source calculation program of Additional remark 4 which makes the said reflection process part function further as a process part which calculates the predetermined brightness in case the said direction (theta) is other by following Formula.
(45 ° -θ) / 45 ° × S
(Additional remark 6) The surface selection part which selects the surface which the light from a light source has hit in the image currently displayed on the computer screen,
A partial selection unit that selects a sun part that is directly hit by the light from the light source and a shadow part that is not hit in the selected surface;
A direction calculation unit for calculating the direction of the light source from the brightness in the selected sun part and shadow part,
A brightness calculator that calculates the brightness reflected on the selected surface based on the calculated direction;
Reflection processing unit that reflects the calculated brightness on the selected surface,
A light source calculator.
(Appendix 6) A surface selection step for selecting a surface on which light from a light source strikes in an image displayed on a computer screen,
A partial selection step of selecting, in the selected surface, a sun part that is directly hit by light from the light source and a shadow part that is not hit;
A direction calculation unit for calculating the direction of the light source from the brightness in the selected sun part and shadow part,
A brightness calculation step for calculating the brightness reflected on the selected surface based on the calculated direction;
Reflection processing step to reflect the calculated brightness on the selected surface,
A light source calculation method comprising:

Diagram Hinata and shade specified on each wall Explanation of desired angle Flow chart of the present invention Original photo Image with outer wall pasted An image that takes into account the original shadow

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen selection part 2 Hinata shade selection part 3 Direction calculation part 4 Brightness calculation part 5 Reflection processing part

Claims (3)

Computer
A surface selection unit that selects a surface that is exposed to light from a light source in an image displayed on a computer screen;
A partial selection unit that selects a sun part that is directly hit by the light from the light source and a shadow part that is not hit in the selected surface;
A direction calculation unit for calculating the direction of the light source from the brightness in the selected sun part and shadow part,
A brightness calculator that calculates the brightness reflected on the selected surface based on the calculated direction;
Reflection processing unit that reflects the calculated brightness on the selected surface,
Light source calculation program to function as. The light source calculation program according to claim 1, further causing the direction calculation unit to function as a processing unit for calculating a direction of a light source by designating two locations from the sunny portion and two locations from the shade portion. When the direction θ is 0 ° or 90 °, the reflection processing unit is configured to add a certain brightness to a surface on which light from the light source is applied, and reduce the brightness on a surface on which the light is not applied, 3. The light source calculation program according to claim 1, wherein when the angle θ is 45 °, the brightness is not corrected, and when θ is otherwise, the light source calculation program further functions as a processing unit for adding or subtracting the predetermined brightness.

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