Dependencies

See the plugin dependencies for the XIMEA plugin. 

Configuration

mira.ini

The Headwall MV.C VNIR has the following options available in the mira.ini file under the acq_HeadwallMVCVNIR section:

  • queueSize: an integer value to define the number of frames in the internal queue, defaults to -1, possible values: -1 (maximum), 0 (minimum), 2..2147483647.
  • processQueuedBuffers: a boolean value to enable queue processing, defaults to true.
  • gain: a floating point value to define the gain setting, defaults to 13.9.

Usage

Queue size and processing

The XIMEA plugin has an internal frame queue which stores frames from the camera until perClass Mira is able to process them. If the frame rate is low enough or the computer fast enough, then there may be a few frames in the queue during normal acquisition. With higher frame rates or slower computers, the queue will fill up more and eventually frames will start to drop.


A high value for the queueSize setting will make acquisition run for as long as possible before frames will start dropping, this does have the issue that once frames start dropping, then the stream may be over 300 frames behind on the real items moving under the camera. If this would happen at 100 FPS, then an object that has passed under the camera will have moved for 3 seconds already before perClass Mira is able to process it. A low value for the queueSize will make the stream as close to the real items as possible, but frames will drop more frequently.


In case that the OS starts a background process (which often happens on Windows), the processing will be blocked for a short time. With a small queue, a lot of frames will be dropped, but with a big queue, the queue will get filled a lot, but if the computer is fast enough, then those queued frames will be processed faster than the normal camera FPS. This can be seen in the Camera panel speed graphs: the camera graph will be stable, go up sharply, then go down sharply to below the stable value, and then back to stable.


If processQueuedBuffers is enabled, then when the acquisition is paused or recording is stopped, perClass Mira will first process all frames that were still in the queue before really stopping. This is for instance useful when a small area will be recorded at a high frame rate on a slow computer, for instance when recording with a stage, the stage can already be finished moving, but perClass Mira will still be saving the final frames.

Troubleshooting

For issues with loading the plugin, see Plugin loading.

Low frame rate

In some cases the OS attaches the camera in USB2 mode, in this case the frame rate will be very low. This can be validated by checking the Output window, there should be a line starting with Available bandwidth, the value after it will be 49 MB/s for USB2 and 396 MB/s for USB3. This problem can usually be fixed by closing the device in perClass Mira, disconnecting the USB cable, connecting the USB cable again, and then opening the camera again.