Understand the mean of dfov and hfov and vfov:A Depth Guide

When designing embedded vision systems, we've likely all faced the question: how can a camera clearly see the world it needs to focus on? To address this, we need to first understand an optical parameter—the field of view (FOV). This parameter defines the camera's field of view.

As a consultant with extensive experience in the camera module field, I will explain the three core FOVs—dFOV, hFOV, and vFOV—in this article, providing practical information to help you make informed decisions when selecting a camera module.

What does field of view (FOV) mean?

Simply put, field of view (FOV) refers to the range of the scene a camera can capture at a given moment. It's typically measured in degrees, similar to the human eye, and determines the area your device can see.

This parameter isn't independent; it's closely related to the camera's lens focal length, sensor size, and the working distance of the object being photographed. In the world of machine vision, choosing the right FOV is like equipping the system with the right "eyes": too narrow a field of view can miss critical information, while too wide a field of view can compromise necessary image resolution and increase lens distortion—both common challenges for engineers.

Thus, understanding the meaning of FOV is the first step in any camera design.

what are HFOV, VFOV, and DFOV？The Three Major Fields of View

In real-world projects, we don't just talk about a general FOV, but instead break it down into three specific dimensions. These three metrics together constitute the complete field of view of a camera.

Horizontal Field of View (HFOV)

HFOV, or horizontal field of view, is the area of the scene that a camera can cover in the left-right direction. It determines how wide your camera can "see" laterally. In many applications, such as autonomous driving, intelligent surveillance, and robotic vision, a wide HFOV effectively reduces blind spots, ensuring the system can capture moving vehicles or pedestrians, and is fundamental to system design.

Vertical Field of View (VFOV)

VFOV, or vertical field of view, defines the angular range of a camera's coverage in the vertical direction. It determines how high or low the camera can "see." For tasks such as drone aerial photography, barcode scanning on an assembly line, and facial recognition, an appropriate VFOV ensures that the target object is completely contained within the frame, rather than being cut off by the edges.

Diagonal Field of View (DFOV)

DFOV, also known as diagonal field of view, refers to the camera's maximum diagonal field of view. It combines the characteristics of HFOV and VFOV, providing a reference for overall field of view capabilities. In many product datasheets, DFOV is often listed first because it provides an intuitive and comprehensive overview of the field of view. However, when designing specific features, it's still important to return to the more practical metrics of HFOV and VFOV.

The Difference and Relationship Between HFOV and VFOV

Engineers often find themselves confused when faced with the question of HFOV versus VFOV. They don't exist independently, but are instead determined by a core factor: the image sensor's aspect ratio and the lens' focal length. For example, a mainstream 16:9 sensor will always have a wider horizontal field of view than its vertical field of view, a fixed triangular geometric relationship between the two.

This means that you can't simply choose HFOV or VFOV independently; they are interconnected and mutually constrained. In practical designs, this inherent connection often presents a painful balancing act for engineers.

HFov VFOV Calculator: How to Calculate Accurately?

Accurately calculating HFOV and VFOV is an essential step in camera module selection. While there are many convenient tools available, such as HFOV and VFOV calculators, understanding the underlying principles is crucial for professional engineers.

We can use basic trigonometry to derive these values. If you know the lens focal length (f) and sensor size (d), you can calculate the corresponding field of view angle.

For example, the formula for calculating horizontal field of view angle is:

HFOV = 2 × arctan(SensorWidth / (2 × FocalLength)).

Similarly, VFOV can be calculated using a similar method. Understanding and applying these formulas will help you achieve more accurate designs, avoiding the hassle of discovering field of view mismatches late in development.

The Importance of Choosing the Right FOV

Choosing the right FOV is a key selling point for a successful embedded vision project. However, the wrong FOV can lead to unexpected and significant problems.

For example, in robotic navigation, a wide DFOV allows the robot to quickly perceive its surroundings. However, if its HFOV is too narrow, it might miss side obstacles, leading to a collision.

For another example, in in-vehicle monitoring, you need more than just a wide-angle lens. You need a precise VFOV to ensure full coverage of all passengers, not just the roof or dashboard.

Problems often arise from a mismatch between requirements and specifications. If your application requires recognizing small objects at a distance, but you choose a lens with a wide DFOV, the pixel density may be too low for effective recognition, ultimately leading to project failure.

Summary: Comprehensive Considerations for DFOV, HFOV, and VFOV

In the world of machine vision, there's no single "optimal" field of view. Every project has its own unique requirements. HFOV, VFOV, and DFOV are like the three-dimensional coordinates that define a camera's "perception boundaries," each essential.

Understanding their relationship, making precise calculations with tools like an HFOV and VFOV calculator, and making informed decisions based on the needs of the actual application scenario are essential skills for every engineer. Only in this way can you ensure your camera module not only sees well, but also sees accurately and clearly, truly empowering your system.

Muchvision help you FOV solution

Need expert guidance on the complexities of field of view (FOV) selection? Contact our team of experts today to help you choose the right camera module for your specific application. Together, we can create a superior embedded vision solution.