Follow

Reprocess (HD)

A range of scenarios is available in the MVN software, which differ mainly in the interaction with the ground, but may affect the behavior of 3D position and orientation. Some scenarios provide the possibility to run the HD reprocessor (MVN 2018 and up). As opposed to the real-time engine or (automatic) reprocessor of MVN, where the data is processed frame by frame, progressing forward in time, the HD reprocessor adds the feature to process data over a larger time window. In this way, the HD reprocess engine is able to include information from the past, present, and future to get an optimal (and more consistent) estimate of the position and orientation of each segment.

This will raise the data quality by extracting more information from the same data set and modeling for skin artifacts, with the purpose to ensure the best results within the chosen type of environment or movements. 

TIP: Reprocessing can be a great tool if you accidentally recorded your files in a wrong scenario. Simply reprocess the file on the correct scenario afterward. 

 

Check file Quality

You can check the quality of your MVN files by opening them in MVN. Then go to File > Properties to go the File properties window. There, you can find "Processed with": 

mceclip1.png

 

Reprocess single file

Click the reprocess button mceclip0.png (see picture), or go to the Tasks tab and click  "Reprocess" (Quick Button: Ctr + Shift + P).

mceclip1.png

In this window, you can change Quality (normal or HD), Scenario or Reset Position. Just clicking "Start Processing" or "Start and Close", the reprocess will start accordingly.

reprocess_single.jpg

Quality - you can process the files at Normal Quality or HD Quality.- reprocess the mvn files before exporting. Options are None, Normal Quality and HD Quality. 
User Scenario - you can select the scenario you want to reprocess your file in. here you can find more information on Scenarios
Processing State - gives information on the processing status of the Engine
Reset Position - reset a specified segment to a specific 3D position (X, Y, Z in meters).
Reset Heading - reset the Pelvis segment to a specific 3D rotation (front of pelvis facing positive X-axis)
Reinitialize Mocap Engine - force the reprocessing to clear out all the engine filters before reprocessing. Typically, this option is not checked. This is only used when both normal and HD reprocess result in bad data.

 

When you've started reprocessing, the timeline will indicate the status of the reprocessing.

For Normal Quality reprocessing it will turn green:

mceclip1.png

 For HD Quality, first the timeline will turn blue (indicating normal processing)

mceclip3.png

Then, the bar will turn light blue. 

mceclip4.png

Batching reprocess of multiple files

Batch Export

If you have multiple files that you'd like to reprocess and export in your preferred format, please go to File > Export > Batch Export and in the Reprocessing option enter "HD Quality". Enable the option "Save MVN file after reprocessing" and you'll use this batch exporter as a "batch (HD) reprocessor" as well.

Annotation_2019-11-08_142847.jpg

Input path - path where MVN files are located which are to be (reprocessed and) exported (can be selected in file explorer by clicking mceclip0.png)
Output path - path where (reprocessed and) exported files will be stored (can be selected in file explorer by clicking mceclip0.png)
Exporter - See exporters  
Output filename - 
complete file name with output name, selected appendices and file type (not adjustable)
Reprocessing - reprocess the mvn files before exporting. Options are None, Normal Quality and HD Quality. 
Save MVN file after reprocessing - save the result of the reprocessing to the MVN file
Force reprocessing - force the reprocessing regardless of the quality of the MVN file.
When "Force reprocessing" is disabled, only normal quality files will be reprocessed into HD.
If you want to batch reprocess from HD to normal quality, you need to enable "Force reprocessing".

Use GNSS Data - check to use GNSS data in the selected exports (checking automatically sets Reprocessing to HD Quality)

 

Batch Reprocess

If you only reprocess multiple files at once, you can use Batch Reprocess (Tasks > Batch Reprocess).

Annotation_2019-11-08_140514.jpg

Input path - path where MVN files are located which are to be reprocessed (can be selected in file explorer by clicking mceclip0.png)
Output path - path where the reprocessed files will be stored (can be selected in file explorer by clicking mceclip0.png)
Reprocessing - you can process the files at Normal Quality or HD Quality.
Force reprocessing  force the reprocessing regardless of the quality of the MVN file
When "Force reprocessing" is disabled, only normal quality files will be reprocessed into HD.
If you want to batch reprocess from HD to normal quality, you need to enable "Force reprocessing".
Use GNSS Data - check to use GNSS data in the reprocessed files

 

Reprocess MVNS files

When you open MVNS file which loads multiple recordings into the same viewport, you can reprocess them into HD quality by using "Reprocess" (Tasks > Reprocess , or CTRL + SHIFT + P). You need to save manually after completion of reprocessing.

Reprocess.jpg

 

Automatic HD Quality reprocessing

By default, MVN will automatically reprocess any file you open to HD quality. To turn that functionality off, In MVN go to Options > Preferences. Under Recordings, you can uncheck the "Automatic reprocess in HD quality. 

mceclip7.png

 

Improving the result of HD reprocess in capturing little motion on the horizontal plane

Situation

When you are planning to capture trials with low dynamic motion especially on the horizontal plane (e.g. squatting, sitting etc), it is recommended to include a short period with dynamic motion before and after the main motion within the trial. This method provides the HD Reprocess feature with sufficient information to compensate magnetic disturbances and prevent orientation drift. 

For example, if you apply HD reprocess on the recording without a short walk, legs may go wrong like this: 

NoShortWalk.gif

If you apply HD reprocess on the whole recording including short walk before and after sitting, the result should be better.

ShortWalk.gif

 

Procedure

1. When you press record button, ask the performer to walk around (10-20 sec).
2. Then, the performer can start doing the main motion of interest (e.g. sitting)
3. After that, the performer should walk around again and you can stop recording after the walk.
4. Next, you apply HD reprocess on the whole recording, then crop only the part of the main motion (i.e. sitting) for use.
5. To achieve cropping:
       a.  Select the part you want in timeline by dragging the timeline or using Edit > Mark Selection Start / Mark Selection End. (Shortcut keys “[“ and “]”)
       b.  Go to Edit > Copy selection to new MVN file (Shortcut key “Ctrl+B”)
6 The cropped trial should not be HD reprocessed again, otherwise the result cannot be improved.

 

Was this article helpful?
2 out of 2 found this helpful
Do you have a question? Please post your question in our Community Forum