Acquisition and Streaming - Multiple Components

<< Acquisition and Streaming

Some devices may be able to provide multiple pieces of data in a single data streams. For example, there could be a camera that sends two pieces of data, one being a color image and the seconds some metadata such as timestamp and location. As these two pieces of information are different but related (unlike a camera sending two data streams), these will be presented as a single Cvb::Composite object.

C++C#Python

C++

using namespace Cvb;
 
auto devices = DeviceFactory::Discover(DiscoverFlags::IgnoreVins);
auto device = DeviceFactory::Open<GenICamDevice>(devices[0].AccessToken(), AcquisitionStack::GenTL);
auto stream = device->Stream<CompositeStream>(); // default: index = 0 (1)
stream->Start();
 
while(true)
{
  CompositePtr composite;
  WaitStatus status;
  NodeMapEnumerator nodeMaps;
  std::tie(composite, status, nodeMaps) = stream->Wait(); // (2)
 
  for (int i = 0; i < composite->ItemCount(); i++) // (3)
  {
    auto component = composite->ItemAt(i);
    if (auto image = get_if<ImagePtr>(&component))
    {      
      // Process image
    }
    else if (auto pointCloud = get_if<PointCloudPtr>(&component))
    {      
      // Process point cloud
    }
  }
}
 
stream->Abort();

C#

using Stemmer.Cvb;
using Stemmer.Cvb.Driver;
using Stemmer.Cvb.Runtime.InteropServices;
 
using (var devices = DeviceFactory.Discover(DiscoverFlags.IgnoreVins))
{
  using (var device = (GenICamDevice)DeviceFactory.Open(devices[0], AcquisitionStack.GenTL))
  {
    var stream = device.GetStream<CompositeStream>(0); // (1)
    stream.Start();
 
    while(true) {
      WaitStatus status;
      using (var composite = stream.Wait(out status)) // (2)
      {
        foreach (var part in composite) // (3)
        {
          if (part.GetType() == typeof(Image)) {
            var image = Image.FromHandle(part.Handle, ShareObject.No);
            // Process image
          }
          else if (part.GetType() == typeof(PointCloud)) {
            var pointCloud = PointCloud.FromHandle(part.Handle, ShareObject.No);
            // Process point cloud
          }
        }
      }
    }
    
    stream.Abort(); // (6)
  }
}

Python

import cvb
 
devices = cvb.DeviceFactory.discover_from_root(cvb.DiscoverFlags.IgnoreVins)
with cvb.DeviceFactory.open(devices[0].access_token, cvb.AcquisitionStack.GenTL) as device:
    stream = device.stream(cvb.CompositeStream) # default: index = 0 (1)
    stream.start()
  
    while True:
      composite, status, node_maps = stream.wait() # (2)
      with composite:
        for part in composite: # (3)
          if isinstance(part, cvb.Image):
            # Process image
          elif isinstance(part, cvb.PointCloud):
            # Process point cloud
 
    stream.abort() # (6)

Note: Error handling has been omitted from the above example.

Note: In this example, we treat each component as potentially being a different type on each frame. In reality, for a specific camera model, the component type at each index should not change type (i.e. item 1 is always the image, item 2 is the metadata, etc).

1. The device and stream are opened as normal. To ensure that all components can be received, the stream must be of type Cvb::CompositeStream.
2. The composite is read from the stream in the same manner as a normal image.
3. Each component of a Cvb::Composite has a specified type, Cvb::Image, Cvb::PointCloud, etc. The type of the component is checked to determine how to process it.