焦深
介绍
Depth of Focus describes the range of distances where an object appears in focus. Objects outside this range will appear blurry.
In this article, we will explain the basic principles of Depth of Focus and how to apply these principles to Zivid cameras.
What is focus?
Focus is determined by the Circle of Confusion (CoC). The CoC is the radius, or area, covered by light from a point as it hits the imaging sensor after passing through the camera lens. An object is out of focus when the CoC is large enough to cover more than one pixel, causing signal loss and noise. When the aperture is sufficiently large, objects too close to the lens will be focused in front of the sensor, and objects too far will be focused behind the sensor, both resulting in blur. See the illustration below.
Depth of Field
The Depth of Field is the range of distances where an object is in focus. The boundaries are defined by the near focus distance (\(d_{near}\)) and the far focus distance (\(d_{far}\)). Outside these boundaries, the CoC increases, causing light to spread into neighboring pixels.
The angles at which the lens refracts the light rays grow with the aperture size. For Zivid 3D cameras, a large aperture can cause objects to lose focus, reducing the Signal-to-Noise Ratio (SNR) and making the point cloud noisier. Therefore, selecting the appropriate aperture for the camera’s working distance is crucial for optimal image quality.
焦点如何影响我的点云？
As the image gets more out of focus, artifacts such as noise and 对比度失真 will increase. When we speak about noise, we are talking about the point precision of the point cloud. This means that the capture-to-capture variations of a given pixel will increase and that the pixel-to-pixel variation within for a given capture will increase. It is important to be aware that a slight increase in noise may still be acceptable. Slight increases in noise may be acceptable depending on the processing algorithm used. Therefore, an unfocused image can still be acceptable in many cases.
备注
Zivid cameras are robust against defocus!
It is also important to note that only the out-of-focus regions of the image will be affected. Consider the camera’s working distance for the given application to achieve good point clouds with optimal precision.
Zivid 相机的焦深
The table below shows the Depth of Focus for Zivid cameras.
Zivid 2+ M130/MR130 |
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|---|---|---|---|---|---|---|---|---|---|
\(f\) -值 |
\(f/2\) |
\(f/2.8\) |
\(f/4\) |
\(f/5.6\) |
\(f/8\) |
\(f/11\) |
\(f/16\) |
\(f/22\) |
\(f/32\) |
Stops |
+3 |
+2 |
+1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
近焦点 (mm) |
1115 |
1055 |
975 |
885 |
780 |
680 |
560 |
460 |
355 |
远焦点（mm） |
1560 |
1695 |
1945 |
2430 |
3880 |
15120 |
Inf [1] |
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景深 (mm) |
445 |
640 |
970 |
1545 |
3095 |
14440 |
Inf [1] |
Inf [1] |
Inf [1] |
Zivid 2+ L110/LR110 |
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|---|---|---|---|---|---|---|---|---|---|
\(f\) -值 |
\(f/2\) |
\(f/2.8\) |
\(f/4\) |
\(f/5.6\) |
\(f/8\) |
\(f/11\) |
\(f/16\) |
\(f/22\) |
\(f/32\) |
Stops |
+3 |
+2 |
+1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
近焦点 (mm) |
800 |
720 |
630 |
535 |
440 |
360 |
275 |
215 |
155 |
远焦点（mm） |
1769 |
2310 |
4375 |
Inf [1] |
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Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
景深 (mm) |
960 |
1590 |
3745 |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
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Zivid 2+ M60/MR60 |
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|---|---|---|---|---|---|---|---|---|---|
\(f\) -值 |
\(f/2\) |
\(f/2.8\) |
\(f/4\) |
\(f/5.6\) |
\(f/8\) |
\(f/11\) |
\(f/16\) |
\(f/22\) |
\(f/32\) |
Stops |
+3 |
+2 |
+1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
近焦点 (mm) |
500 |
465 |
425 |
380 |
330 |
285 |
230 |
185 |
140 |
远焦点（mm） |
755 |
840 |
1010 |
1390 |
3200 |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
景深 (mm) |
255 |
370 |
585 |
1010 |
2870 |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
Zivid 2 M70 |
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|---|---|---|---|---|---|---|---|---|---|
\(f\) -值 |
\(f/2\) |
\(f/2.8\) |
\(f/4\) |
\(f/5.6\) |
\(f/8\) |
\(f/11\) |
\(f/16\) |
\(f/22\) |
\(f/32\) |
Stops |
+3 |
+2 |
+1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
近焦点 (mm) |
530 |
480 |
420 |
370 |
300 |
250 |
190 |
150 |
110 |
远焦点（mm） |
1040 |
1280 |
1990 |
7630 |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
景深 (mm) |
510 |
800 |
1570 |
7260 |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
Inf [1] |
Zivid 2 L100 |
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|---|---|---|---|---|---|---|---|---|---|
\(f\) -值 |
\(f/2\) |
\(f/2.8\) |
\(f/4\) |
\(f/5.6\) |
\(f/8\) |
\(f/11\) |
\(f/16\) |
\(f/22\) |
\(f/32\) |
Stops |
+3 |
+2 |
+1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
近焦点 (mm) |
680 |
605 |
520 |
430 |
350 |
280 |
210 |
160 |
120 |
远焦点（mm） |
1870 |
2870 |
14290 |
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Inf [1] |
Inf [1] |
Inf [1] |
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景深 (mm) |
1190 |
2260 |
13770 |
Inf [1] |
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焦深计算器
通过使用Zivid的 焦深计算器，可以根据工作距离和可接受的模糊半径找到推荐的最大光圈。请记住，在感兴趣的区域获得清晰的图像是获得最佳点云质量所需的许多条件之一，但这不是硬性限制。如上所述，Zivid 3D技术具有非常强的抗模糊和散焦能力。即使图像看起来失焦，它仍然能够提供良好的点云，尽管它们可能会看起来有点嘈杂。