Discovering and Selecting Cameras#

This topic explains the process of discovering and selecting cameras to work with.

Before an application can use a camera, it must first discover which cameras are available. This process is called enumeration.

Enumerating Cameras#

Unlike consumer cameras (e.g., webcams), industrial cameras aren't automatically tied to a single application. Instead the following is true:

• Multiple cameras may be connected at the same time.
• Cameras may be connected via different transport layers, e.g., USB, GigE, etc.
• Cameras may appear/disappear dynamically, e.g., due to hot-plugging or network changes.

Enumeration allows your application to achieve the following:

• Detect all cameras currently available.
• Identify them reliably.
• Select the correct camera for your task.

例#

factory = pylon.TlFactory.GetInstance()

The transport layer factory is the entry point into the pylon ecosystem. It's responsible for these tasks:

• Discovering cameras.
• Creating device instances.
• Abstracting the underlying transport layers, e.g., USB, GigE, etc.

Think of it as a device manager.

device_info_list = factory.EnumerateDevices()

This returns a list of device descriptors. Each entry contains metadata about a detected camera, such as:

• Model name
• Serial number (unique identifier)
• Interface type (USB, GigE, etc.)

for device_info in device_info_list:
    print(device_info.GetFriendlyName())
    print(device_info.GetSerialNumber())

Mental Model#

System Startup
     ↓
Transport Layers Scan for Devices
     ↓
Detected Camera List (Enumeration)
     ↓
Application selects a camera

Selecting a Camera#

You can select cameras by serial number or by using the index.

Serial Number (Recommended)#

This is the recommended method to select a camera.

serial_number = "123456"

for device_info in device_info_list:
    if device_info.GetSerialNumber() == serial_number:
        camera = pylon.InstantCamera(factory.CreateDevice(device_info))

Index#

device_info_list[0]

使用事例#

Single Camera Systems#

Use pylon.InstantCamera(pylon.FirstFound).

Key characteristics:

• Sufficient for testing simple setups.
• For single camera use cases, you can let pylon find your camera by passing the required properties as a dictionary.
• Not recommended for multi-camera use cases.

camera = pylon.InstantCamera({pylon.SerialNumberKey : serial_number}, pylon.FirstFound)

Multi-Camera Systems#

Basler recommends enumerating the devices first. Afterwards, you can select the desired camera by its unique identifier, e.g., its serial number, to avoid the overhead of multiple device enumerations.

• Enumerate all cameras.
• Map cameras by serial number or user-defined name.

Production Systems#

• Store camera identifiers in configuration files.
• Validate presence at startup.
• Fail fast if expected camera is missing.

Key Takeaways#

Enumeration is essential because it makes your application:

• Robust to hardware changes
• Independent of connection order
• Scalable to multiple cameras

Without proper enumeration, systems become fragile and difficult to maintain.