OS: This operator is only supported under the Microsoft Windows operating system.

The OpenVR CHOP receives positional data, frame rendering info, and action data from the OpenVR SDK. Each CHOP can output in one of 5 modes: Sensors, Projection Matrices, Trackers, Frame Timings, Actions and Skeletons.


Actions are described in more details in OpenVR Actions.

Getting Sensor Data at Higher Rates

By default when running a VR system the file will be throttled to the speed of the VR devices refresh rate by the OpenVR SDK. This helps ensure the low latency output required for a good VR experience. If only controllers/Vive trackers are being used for tracking in a non-VR situation, the file can run and sample those devices at a higher sample rate as long as no OpenVR TOP in the project. If an OpenVR TOP is present anywhere in the project, then playback will be throttled to the VR devices refresh rate.

See also OpenVR, OpenVR TOP, OpenVR SOP, Audio Render CHOP


Parameters - Setup Page

Active active - Control if this node is querying data from the OpenVR driver.

Output output - - Controls what kind of category of data will be output from this node.

  • Sensor sensor - Output data such as sensor orientation and general information such as render resolution.
  • Projection Matrices projmatrices - Output the projection matrices for each eye.
  • Trackers trackers - Output tracker states/transforms. This can both include Vive Trackers as well as just the transforms of controllers.
  • Frame Timings frametimings - General information regarding frame rendering.
  • Actions actions - The action channels as defined by the OpenVR Actions in used by the system.
  • Skeletons skeletons - Hand skeletal information, as descibed here. Note that 'Finger Tip Bones' is not supported anymore in OpenVR.

Max Trackers maxtrackers - The maximum number of trackers whose data should be output from this node.

First Tracker firsttracker - The first tracker number to be output. For example if this is set to 2 and Max Trackers is 2, then data for trackers 2 and 3 will be output.

Orientation orientation - When doing 'Sensor' output, controls if the orientation channels will be output. By default the units for orientation are 1 unit = 1 meter.

General Info generalinfo - When doing 'Sensor' output, controls of general information channels will be output, such as render resolution and play area size.

Near near - When outputting 'Projection Matrices', controls the near plane the projection matrix will be built with.

Far far - When outputting 'Projection Matrices', controls the far plane the projection matrix will be built with.

Unit Scale unitscale - OpenVR by default works in a scale where 1 unit = 1 meter. This parameter allows the scale to be changed incase a scene is imported with a different scale.

Custom Actions customactions - Turn on to allow specifying a custom OpenVR Actions manifest file.

Action Manifest actionmanifest - A path to a OpenVR Actions manifest file. By default this is using the same manifest OpenVR uses when Custom Actions is disabled.

Use Legacy Names uselegacynames - Use legacy channel naming convention coming from the Action Manifest. This should stay off unless loading existing old files.

Skeleton Range skeletonrange - - Controls the range of motion of the skeleton values.

  • With Controller withcontroller - Output skeleton taking into account the shape of the controller. The skeleton will look like it's holding the controller.
  • Without Controller withoutcontroller - Output the skeleton as if the controller dose not exist. This allows the skeleton to create a fully closed fist.

Parameters - Common Page

Time Slice timeslice - Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.

Scope scope - To determine which channels get affected, some CHOPs use a Scope string on the Common page.

Sample Rate Match srselect - - Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.

  • Resample At First Input's Rate first - Use rate of first input to resample others.
  • Resample At Maximum Rate max - Resample to the highest sample rate.
  • Resample At Minimum Rate min - Resample to the lowest sample rate.
  • Error If Rates Differ err - Doesn't accept conflicting sample rates.

Export Method exportmethod - - This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.

  • DAT Table by Index datindex - Uses the docked DAT table and references the channel via the index of the channel in the CHOP.
  • DAT Table by Name datname - Uses the docked DAT table and references the channel via the name of the channel in the CHOP.
  • Channel Name is Path:Parameter autoname - The channel is the full destination of where to export to, such has geo1/transform1:tx.

Export Root autoexportroot - This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.

Export Table exporttable - The DAT used to hold the export information when using the DAT Table Export Methods (See above).

Info CHOP Channels

Extra Information for the OpenVR CHOP can be accessed via an Info CHOP.

Common CHOP Info Channels

  • start - Start of the CHOP interval in samples.
  • length - Number of samples in the CHOP.
  • sample_rate - The samplerate of the channels in frames per second.
  • num_channels - Number of channels in the CHOP.
  • time_slice - 1 if CHOP is Time Slice enabled, 0 otherwise.
  • export_sernum - A count of how often the export connections have been updated.

Common Operator Info Channels

  • total_cooks - Number of times the operator has cooked since the process started.
  • cook_time - Duration of the last cook in milliseconds.
  • cook_frame - Frame number when this operator was last cooked relative to the component timeline.
  • cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.
  • cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.
  • cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.
  • cooked_this_frame - 1 if operator was cooked this frame.
  • warnings - Number of warnings in this operator if any.
  • errors - Number of errors in this operator if any.

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