JPS63235827A - Visibility measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the visibilities of an object at various positions in a visual field simultaneously, by providing a brightness distribution measuring part and a dimension condition setting part. CONSTITUTION:A brightness distribution measuring part 1 measures the brightness distribution of a visual field and calculates the part surrounded by the lattices wherein the visual field is divided in a lattice form and outputs the signal corresponding thereto to a brightness difference calculation part 4. The visual angle dimension of an object whose visibility must be calculated is inputted to a dimension condition setting part 3 and the signal corresponding thereto is outputted to a brightness difference discriminating threshold correction part 8. The calculation part 4 calculates the difference between the brightness of each object and that of the background adjacent thereto at every object to output the same to a visibility calculation part 9. Further, an equivalent luminance measuring part 5 measures the equivalent luminance of the eye-sight of an observer and a central pit adaptation brightness measuring part 6 measures the brightness adapting to the central pit of an eye and both measuring parts 5, 6 output the corresponding signals. A brightness difference discrimination threshold calculation part 7 inputs the signals from the measuring parts 5, 6 and calculates a brightness difference discrimination threshold when each object is observed from said signals to output the signals corresponding to the respective signals to a brightness difference discrimination threshold correction part 8. Therefore, the visibility can be measured simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for measuring the visibility of objects within a field of view.

2. Description of the Related Art A block diagram of a conventional visibility measuring device is shown in FIG. 11 is a brightness distribution measuring section, 12 is an object condition setting section, 1
3 is a brightness difference calculation unit; 14 is an equivalent light curtain brightness measurement unit; 15 is a foveal adaptation brightness measurement unit; 16 is a brightness difference discrimination threshold calculation unit;
7 is a visibility calculation section, and 18 is a visibility distribution map display section.

The operation of the conventional visibility measuring device will be explained below with reference to FIG. The brightness distribution measurement unit 11 measures the ll11 degree distribution of the visual field that includes the object whose visibility is to be measured, divides the visual field into grids, calculates the brightness of the area surrounded by each grid, and calculates the brightness of each part. A signal corresponding to the brightness value is output to the brightness difference calculation unit 13. The position and brightness (Lo) of each of a plurality of objects whose visibility is to be determined are input to the object condition setting section 12, and signals corresponding to these are output to the brightness difference calculation section 13. The brightness difference calculation unit 13 calculates the difference (Δ) between the brightness of each object and the brightness (Lb) of the background adjacent to it.
L=lLo−Lbl) is calculated for each object and output to the visibility calculation unit 17. The equivalent light curtain brightness measurement unit 14 measures the equivalent light curtain brightness (
Leq) and outputs a signal corresponding to it. The foveal adaptation brightness measurement unit 15 measures the brightness to which the fovea of the observer's eye is adapted when looking at each object (foveal adaptation brightness Laf), and outputs a signal corresponding to the brightness. . The luminance difference discrimination threshold calculation unit 16 inputs a signal corresponding to the equivalent light curtain luminance and a signal corresponding to the foveal adaptation luminance, calculates a luminance difference discrimination threshold when observing each object from these, and calculates the luminance difference discrimination threshold for each object. A signal corresponding to is output to the visibility calculation unit 17. In this case, the luminance difference discrimination threshold (ΔLa1n) when observing a certain object is the equivalent light screen 1 at that time.
11 degree difference discrimination flash (ΔLmin(Le
q)) and the brightness difference discrimination threshold (ΔLmin(Laf)) determined by the foveal adaptation brightness. That is, ΔLmin=ΔLmin(Laf)+ΔLmin(Le
q)”・(1).

The visibility calculation section 17 calculates the visibility (VL) of each object from the signal input from the brightness difference calculation section 13 and the signal input from the brightness difference discrimination threshold calculation section 16, and calculates the visibility (VL) of each object. A signal corresponding to the degree of visibility is output to the visibility distribution chart display section 18. In this case, the visibility V■- is determined from the ratio of the difference ΔL between the I1 degree of the object and the luminance of its background and the luminance difference discrimination threshold ΔLmin.

That is, visibility: VL=ΔL/Δ1m1n (2),
The visibility distribution map display unit 18 displays a diagram of the visibility distribution state of an object at an arbitrary position within the field of view.

Problems to be Solved by the Invention In conventional devices, the value of the luminance difference discrimination threshold obtained from the respective measured values of foveal adaptation luminance and equivalent light screen luminance is determined for a constant visual angle dimension index. The value of the luminance difference discrimination threshold was used. However, the brightness difference discrimination threshold of the human eye changes depending on the visual angle dimension of the target index, so the visibility of the target obtained with conventional equipment is determined by the luminance difference discrimination threshold used at that time. It is a correct value only when the threshold is equal to the presentation time of the determined index, and accurate visibility cannot be obtained for objects with other viewing angle dimensions.Therefore, with conventional visibility measurement devices, It was not possible to accurately determine the visibility of objects with various viewing angle dimensions.

Means for Solving the Problems The present invention comprises a first measuring section that measures the luminance distribution, a first condition setting section that sets conditions for the luminance and position of an object, and the first measuring section. a first calculation section that inputs the signal from the first condition setting section and calculates the luminance difference between the object and its background; and a second calculation section that measures the equivalent light screen luminance of the eye of an observer viewing the object. a third measuring section that measures the brightness to which the fovea of the observer's eye is adapted; a second calculation unit that calculates a luminance difference discrimination threshold; a second condition setting unit that sets a viewing angle dimension of the object; and signals from the second calculation unit and the second condition setting unit are input. a third calculation unit that calculates a luminance difference discrimination threshold; and a visibility calculation unit that receives signals from the first calculation unit and the third calculation unit and calculates the visibility of the object. It is a visibility measuring device.

Operation The present invention uses the above-described means to determine the brightness distribution within the visual field, and calculates the difference between the brightness of an object located at an arbitrary position within the visual field and its background from the measured value of this brightness distribution. on the other hand,
A brightness difference discrimination threshold is calculated from the equivalent light curtain brightness and foveal adaptation brightness of the eyes of the observer looking at the object. Next, a brightness difference discrimination threshold with the viewing angle dimension corrected is calculated from the calculated brightness difference discrimination threshold value. The visibility of the object is calculated from the difference between the brightness of the object and its background and the brightness difference discrimination threshold.

Embodiment A block diagram of a visibility measuring device according to the present invention is shown in FIG. 1. 1 is a brightness distribution measuring section, 2 is an object condition setting section,
3 is a dimension condition setting section, 4 is a luminance difference calculation section, 5 is an equivalent light curtain degree measurement section, 6 is a foveal adaptation 11 degree measurement section, 7 is a luminance difference discrimination threshold calculation section, 8 is a luminance difference discrimination threshold correction 9 is a visibility calculation section, and 10 is a visibility distribution map display section.

The operation of an embodiment according to the present invention will be explained below with reference to FIG. The brightness distribution measurement unit 1 measures the brightness distribution of the field of view that includes the object whose visibility is to be measured, divides the field of view into grids, calculates the brightness of the area surrounded by each grid, and calculates the brightness of each field. A signal corresponding to the brightness value is output to the brightness difference calculation unit 4. Zero dimension condition setting in which the position and brightness (Lo) of each of the plurality of objects whose visibility is to be determined is input to the object condition setting section 2, and signals corresponding to these are output to the brightness difference calculation section 4. The viewing angle dimensions of the object whose visibility is to be determined are input to the section 3, and signals corresponding to these are output to the brightness difference discrimination threshold calculation section 8. The brightness difference calculation unit 4 calculates the difference (Lb) between the brightness of each object and the brightness (Lb) of the background adjacent to it.
ΔL=I Lo−Lbl ) is calculated for each object and output to the visibility calculation unit 9. The equivalent light curtain brightness measuring section 5 determines the equivalent light curtain brightness (Leq) of the observer's eyes when looking at each object, and outputs a signal corresponding to the equivalent light curtain brightness (Leq). The foveal adaptation brightness measurement unit 6 measures the brightness to which the fovea of the observer's eye is adapted when looking at each object (foveal adaptation brightness Laf), and measures the brightness corresponding to the brightness Laf. Output. The II degree difference discrimination threshold calculation unit 7 inputs the signal corresponding to the equivalent light intensity and the signal corresponding to the center 'a, m corresponding brightness, and calculates the brightness difference discrimination when observing each object from these. Thresholds are calculated and signals corresponding to the thresholds are output to the brightness difference discrimination threshold correction section 8. In this case, the brightness difference discrimination threshold (ΔL m
in) is the luminance difference discrimination threshold (ΔLmin(Leq)) determined by the equivalent light screen luminance at that time and the luminance difference discrimination threshold (ΔLmin(Laf)) determined by the foveal adaptation luminance.
From this, it can be obtained from equation (1). FIG. 3 shows the relationship between the luminance difference discrimination threshold determined by the equivalent light curtain luminance and the equivalent light curtain luminance, and the relationship between the luminance difference discrimination threshold determined by the foveal adaptation luminance and the foveal adaptation luminance.

The brightness difference discrimination threshold correction unit 8 corrects the visual angle dimension to the value of the brightness difference discrimination threshold determined by equation (1), and creates a brightness difference discrimination threshold corresponding to the visual angle dimension of the object whose visibility is to be determined. are calculated, and signals corresponding to each are output to the visibility calculation unit 9. In this case, the value of the industrial strength difference discrimination threshold obtained from equation (1) and FIG. 3 is the value obtained for an index whose viewing angle dimension is 10 minutes. The brightness difference discrimination threshold ΔLmin under conditions where the viewing angle size is different from this is ΔLmin=ΔLminuo+X (2 for kl/s+)/(2 for kl/10+)X
((F(L)2+G(s)2) ”2+3.8): (
(F(L)2+0.034)! '2+3.8)
-...It is obtained from (3).

Here, ΔL111in+101 is expressed by equation (1) and the third
The brightness difference discrimination threshold [cd/m2] obtained from the figure, S is the visual angle dimension [minute 1] of the object, and F(L) and G(s) are obtained from the following equations.

F(L) = 0.355-0.12I7 (logL+
6.0)2+((logL+6.0)2-10.4(l
ogL+6.0)+52.28)-...(4) Here,
L is equivalent uniform luminance [cd/m2]. Also, G (
s)=0.36-0.0972(]ogs+0.52
3) “÷((Iogs+0.523)”-2,51
3(Iogs+0.523)+2.7895)...(
5).

Further, kL and 2 are experimental constants determined by the equivalent uniform luminance, as shown in Table 1.

The visibility calculation section 9 calculates the visibility (VL') of each object from the signal input from the brightness difference calculation section 4 and the signal input from the brightness difference discrimination threshold correction section 8, and In the case of outputting a signal corresponding to the visibility to the visible variation I1j chart display unit 10, the visibility Vl is determined by the difference ΔL between the luminance of the object and its background and the luminance difference discrimination threshold ΔLmin. It can be found from the ratio.

That is, visibility: VL=ΔL/ΔLmin (2). The visibility distribution map display unit 10 displays a diagram of the visibility distribution state of an object at an arbitrary position within the field of view.

Note that the brightness distribution measuring section 1 can be configured by combining a brightness meter and a personal computer. Further, the equivalent light screen brightness measuring section 5 can be constructed by combining a glare lens and a brightness meter, which have the same scattering characteristics as the light scattering characteristics within the human eyeball.

Effects of the Invention According to the present invention, the visibility of objects at various positions within the visual field can be measured at once. In addition, since it is possible to accurately consider the influence of scattered light within the eyeball caused by light that enters the eye from the peripheral vision when viewing an object, the visibility when viewing the actual object can be accurately calculated. You can ask for it. Furthermore, even if the object does not actually exist within the field of view, the visibility of the virtual object can be determined by setting the position and brightness conditions, and the visibility can be simulated.

4. Brief explanation of the drawings Fig. 1 is a block diagram of a visibility measuring device according to an embodiment of the present invention, Fig. 2 is a block diagram of a conventional visibility measuring device, and Fig. 3 is a diagram showing equivalent light curtain brightness and center FIG. 4 is a relationship diagram between foveal adaptation brightness and a brightness difference discrimination threshold determined by each.

Claims (1)

[Claims] A first measurement section that measures the luminance distribution, a first condition setting section that sets conditions for the luminance and position of the object, and input signals from the first measurement section and the first condition setting section. A first calculation unit that calculates the brightness difference between the object and its background, a second measurement unit that measures the equivalent light screen brightness of the observer viewing the object, and a second measurement unit that calculates the luminance difference between the object and its background; a third measuring section that measures the adapted luminance; and a second calculation that inputs signals from the second measuring section and the third measuring section and calculates a luminance difference discrimination threshold for the clothes of the observer. a second condition setting section for setting the viewing angle dimension of the object; and a third calculation section for calculating a luminance difference discrimination threshold by inputting signals from the second calculation section and the second condition setting section. and a visibility calculation unit that receives signals from the first calculation unit and the third calculation unit and calculates the visibility of the object.