Reflection Filter

The Reflection filter removes points that Zivid deem as impacted by reflection and thus erroneous. These are typically seen in the point cloud as “ghost planes” - small regions of points floating mid-air that shouldn’t be there.

Zivid knows how the signals it sends out from the projector should look like. For this reason it is possible to assess whether or not the data that is read back by the camera makes sense. The reflection filter, therefore, attempts to discard pixels that are deemed to be tampered with as a result of one of the following:

  • Interreflections

  • Excessive movements in the scene

  • Alternating alien light sources

    • For example a second Zivid 3D camera that projects onto the same scene at the same time.

The following values should be used:

Value

Condition

Enabled::no

If you know that your scene is not reflective, and you want to optimize acquisition time.

Enabled::yes

Turn on if you have issues detecting parts that are reflective or are inside a reflective bin.

Reflection Filter disabled and enabled

The Reflection filter has two modes: Global (default) and Local. These modes have different benefits and downsides, depending on the used Vision engine.

Mode

Pros

Mode::global

  • Higher dynamic range with lower exposure

Mode::local

The images below highlight the main advantage of Global mode, its higher dynamic range, as can be seen on the coverage on shiny black objects in this scene.

Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode

Although Local mode has a reduced dynamic range, this can be compensated for by increasing the exposure time, as demonstrated in the comparison images.

Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode (increased exposure) Reflection Filter - Local mode (increased exposure)

The images below illustrate the benefits of Local mode.

Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode
Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode
Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode
Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode

Mode

Pros

Mode::global

  • Preserving the sides and edges of objects

  • Removing outlier points in the point cloud

Mode::local

The images below highlight the main advantages of Global mode: better data on object sides and edges, and fewer outliers.

Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode
Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode

The floating points (outliers) that Local mode cannot remove are typically removed by the Cluster Filter.

The images below illustrate the benefits of Local mode: preserving data on thin and pointy objects.

Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode
Reflection Filter - Global mode Reflection Filter - Global mode
Reflection Filter - Local mode Reflection Filter - Local mode

Reflection filter (Global mode) adds the following processing time per 3D capture:

No additional processing time is added when using the Omni engine.

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2+R2+2
High-end NVIDIAHigh-end IntelHigh-end NVIDIAHigh-end IntelHigh-end NVIDIAHigh-end Intel
Filters
ReflectionGlobal6 ms (±1)10 ms (±1)5 ms (±1)11 ms (±2)14 ms (±8)30 ms (±5)
ReflectionLocal0 ms (±0)0 ms (±0)0 ms (±0)0 ms (±0)0 ms (±0)0 ms (±0)

Version History

SDK

Changes

2.16.0

Reflection filter mode Local can now be used with the Omni engine.

2.12.0

Stripe Engine removed from experimental. Reflection filter mode Local is now up to 15% faster.

2.11.0

Reflection filter mode Local can now be used with the Stripe engine.

2.7.0

Reflection filter is updated with a new mode called Local. Old mode is renamed to Global.

1.4.0

Reflection filter is improved to remove fewer good points.