Understanding the Sequence Detection Tool

The Sequence Detection tool helps you see the interactions of each sequence with the elements hit by the rays as well as the order in which elements have been hit.

Note: The Sequence Detection Tool is not compatible with Isolated Simulations.

The Sequence Detection tool provides you with two lists:

  • The list of sequences
  • The list of interactions


List of Sequence

The list of sequences provides the different paths taken by the rays, calculated either according to the faces (F) or the geometries (G) the rays hit.

For more information on the sequence, see Stray Light Analysis Overview.

The sequences of the List of sequences are sorted:
  • by descending order of Energy (%) values for Radiance and Intensity sensors.

  • by descending order of Energy (%) or Peak values for Irradiance sensors according to the value set for the Sort sequence per parameter.

    The goal of Peak is to identify bright spots that affect and degrade the overall image quality. Since the bright spot's energy is concentrated into a small portion of the sensor area, the energy level does not reflect its actual contribution. Sorting the sequences per peak contribution across the irradiance sensor can help you analyze the distribution of impacts sequence by sequence, so areas with high density of impacts are identified.

    Example: Direct Simulation with a Physical Camera. Sequence file from a previous simulation has been used to highlight the differences in terms of sequence ranking.

    Sequence sorted by decreasing energy percentage Sequence sorted by decreasing peak values

List of Sequences: Columns

The List of sequences is composed of different columns providing each specific information to carry out a stray light analysis.

The sequences can be sorted by ascending or descending order by clicking on the column header.

  • ID: corresponds to the order of detected sequences which can be defined either by decreasing Energy (%) or decreasing Peak.

    Peak values are only available for Irradiance sensors.

    Important: Th Energy (%) is computed using the total radiometric energy of the layers, whatever the XMP type (radiometric, photometric, spectral, colorimetric).

  • Length: corresponds to the number of interactions of the sequence.

    Tip: To display the interactions of the sequence in the list of interactions, select the sequence. Click Cancel sequence selection to display all interactions.
  • No. hits: corresponds to the number of rays that followed the sequence and hit the sensor.
  • Energy(%): corresponds to the percentage of energy contribution of the sequence compared to the total energy of the map.

  • Average (W/m²): corresponds to the average absolute energy of the sequence divided by the surface of the sensor.

    The closer Average (W/m²) and Peak (W/m²), the more uniform the sequence.

    Average values are only available for Irradiance sensors.

  • Peak (W/m²): corresponds to the maximum energy in W/m² of the sequence, calculated on a small area with the highest density of impacts, and averaged on this small area.

    Peak (W/m²) column appears only in case of an Irradiance or Illuminance map. In both cases, Peak will display a value in W/m².

    The closer Average (W/m²) and Peak (W/m²), the more uniform the sequence.

    CAUTION: Peak value in the Sequence Detection tool is different from the Maximum value of a sequence in the Measure tool. The Maximum value in the Measure tool is calculated by finding the brightest pixel.
  • Spec R: number of specular reflections of the sequence
  • Lamb R: number of lambertian reflections of the sequence
  • Gauss R: number of gaussian reflections of the sequence
  • Spec T: number of specular transmissions of the sequence
  • Lamb T: number of lambertian transmissions of the sequence
  • Gauss T: number of gaussian transmissions of the sequence

List of Interactions

The list of interactions lists the interactions of the rays with the elements of the optical system.

  • When a result has been generated using "faces" sequence layer parameter, the list of interactions provide the different faces that rays have interacted with.

    Example: Optical Surface Rectangular.1:3176.Face.1 for the first face of "Optical Surface Rectangular.1:3176" body

    Note: Face names defined in the Speos are not retrieved by the Sequence Detection tool in case of sequences by faces. The Sequence Detection tool only knows the name of the body on which the faces belong. Each face of a body is identified by a unique number (integer): .Face.1 for the first face of the body found in the list, .Face2, for the second one, etc.

  • When a result has been generated using "geometries" layer parameter, the list of interactions provide the different bodies that rays have interacted with.

    Example: Optical Surface Rectangular.1:3174

  • When an interaction has no face name, that means it corresponds to the interaction with a sensor.

  • When you select a sequence in the list of sequences, only the interactions of the sequence appears in the list of interactions in the order of impact.

    A face name can be listed several times in the list of interactions. For instance, when the face is considered for transmission and reflection.

    An interaction can be listed several times in the list of interactions when you select a sequence as rays can have interacted several times with the face/geometry.

Sequence Detection Filter

The Sequence Detection Filter helps you find specific sequences in the list of sequences using the different filtering options.

The filtering options are independent of each other, but can be combined to define more advanced filtering.

Filtering Option: Interaction IDs

The Interaction IDs filtering option allows you to define lists of interactions using regular expressions (regex).

Example: you want to display the sequences that include the interactions 34 and 35 in raw, that can be either at the beginning, at the end, or in the sequence: 34 35 |^34 35 | 34 35$|^34 35$

Important: The space before and after an interaction ID is important to make sure that it will consider the exact ID. For instance, if no space were inserted before and after 34, the filtering would have displayed sequences containing IDs with "34" such as "134" or "340" besides the "34".

As a result, sequences that include at least 1 time the interactions 34 and 35 in raw will appear in the list of sequences.



Filtering Option: Thresholds

The Thresholds allow you to define two filtering criteria based on the available columns.

From and To are used to define the minimum and maximum values to search in the available sequences.

Example: you want to display all sequences with a relative Energy (%) greater than or equal to 3.