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dist.py aims to measure the distance of the object from the camera. This is not an accurate measure and needs better guidance.

However, creating a utility where users can input camera specifications to automatically calculate the field of view (FOV) and subsequently use this to determine the scale of pixels per meter or centimeter is a very practical and useful approach. This method can help in automatically adjusting the measurement scale based on different camera setups without manual calibration.

Here's a breakdown of what the code can do and how to structure it:

Steps to Implement the Code

  1. Input Camera Specifications:

    • The user will input the camera's sensor size (width in mm), focal length (in mm), and the distance from the camera to the object (in meters).

  2. Calculate the Horizontal Field of View:

    • Use the formula for the horizontal field of view: [ FOV = 2 \times \text{atan}\left(\frac{\text{sensor width}}{2 \times \text{focal length}}\right) ]
    • This gives you the FOV in radians, which you can convert to degrees if needed.

  3. Determine Real-world Width of the View at a Certain Distance:

    • Calculate the real-world width of the view at the given distance using the FOV: [ \text{Width at distance} = 2 \times (\text{distance to object} \times \text{tan}(\text{FOV}/2)) ]

  4. Convert the Real-world Width to Pixels:

    • Using the video's resolution (width in pixels), establish how many pixels represent the real-world width calculated in the previous step.

  5. Implement Pixel per Meter/Centimeter Conversion:

    • Use the pixel width to determine the scale of pixels per meter or centimeter.

Example code in fov.py.

To use the function calculate_pixels_per_meter effectively, you'll need realistic values for the camera's sensor width, focal length, distance to the object, and video resolution width. Here are some typical values you might encounter with a standard digital camera or a smartphone, which you can use as input for the calculations:

Example Inputs

  1. Camera Sensor Width: This is typically measured in millimeters. For most consumer cameras and smartphones, sensor widths can range from around 4 mm to around 35 mm for more professional equipment. Let's use a common sensor size for smartphones:

    • Sensor Width: 6 mm (0.006 meters when converted)

  2. Focal Length: This is the distance between the camera sensor and the lens when the subject is in focus, typically measured in millimeters. Common focal lengths for smartphone cameras range from about 4 mm to 10 mm.

    • Focal Length: 4.5 mm (0.0045 meters when converted)

  3. Distance to Object: This depends on what you are measuring. For instance, if you are measuring something in a room or at a short distance:

    • Distance to Object: 5 meters

  4. Video Resolution Width: This depends on the camera's video capturing resolution. Common widths include:

    • 1920 pixels (for full HD)
    • 1280 pixels (for HD)
    • 3840 pixels (for 4K)

Assuming you are using a fairly typical modern smartphone camera capturing in full HD, here are the inputs you might use:

  • Sensor Width: 6 mm
  • Focal Length: 4.5 mm
  • Distance to Object: 5 meters
  • Video Width: 1920 pixels

This is assuming we know how far at least one object is in front of the camera. An ideal set up would include a calibration object place within the field of vision to get an accurate estimate.

Unhappy with perception.py, mouse click trigger very dodgy.