DP44/docs/ai/DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model.md

source_files, generated_at, model, schema_version, sha256

source_files	generated_at	model	schema_version	sha256
DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model/CalculatedChannelCreator.cs	2026-04-17T15:59:43.455218+00:00	zai-org/GLM-5-FP8	1	0bdba55cc7806845

CalculatedChannelCreator Documentation

1. Purpose

The CalculatedChannelCreator class is a factory responsible for creating derived data channels from existing sensor input channels. It performs mathematical transformations—including 3D IR-TRACC displacement calculations, aggregate operations (SUM, AVE, Resultant, HIC), and binary operations (integration, differentiation, trigonometric functions)—on channel data and persists the results to memory-mapped files. This module exists to support post-processing of crash test data, enabling engineers to synthesize new measurement channels from raw sensor inputs.

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2. Public Interface

CreateChannels (static method)

public static Test.Module.CalculatedChannel[] CreateChannels(
    string testId,
    string folder,
    Calculation calculation,
    List<Test.Module.Channel> inputChannels,
    string channelName,
    int startingNumber,
    List<Test.Module.Channel> allChannels,
    int clipLength,
    out List<string> errorList,
    int defaultEncoding)

Behavior: Main entry point for creating calculated channels. Dispatches to appropriate private methods based on the Calculation enum value. Returns an array of Test.Module.CalculatedChannel objects on success, or null if validation fails. Populates errorList with validation errors.

ValidateChannelName (static method)

public static bool ValidateChannelName(
    string channelName,
    List<Test.Module.Channel> inputChannels,
    List<Test.Module.Channel> allChannels,
    out List<string> errorList)

Behavior: Validates that the channel name is non-empty and unique across both input channels and all channels. Returns true if valid; false otherwise. If allChannels is null, validation is bypassed and returns true.

ThreeDIRTraccType (public enum)

public enum ThreeDIRTraccType
{
    Thorax,
    Abdomen,
    LowerThorax
}

Behavior: Specifies the anatomical location for 3D IR-TRACC calculations, which affects the constants (δ and D0) used in the displacement formulas.

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3. Invariants

1. Channel Number Offset: All calculated channels use ChannelNumberCalculationChannelIndicator (constant value 100000) as a base offset for their channel numbers.
2. Sample Rate Compatibility: For aggregate and 3D IR-TRACC operations, the maximum sample rate among input channels must be an integer multiple of each individual channel's sample rate. Otherwise, NotSupportedException is thrown.
3. 3D IR-TRACC Input Count: Create3DIRTraccChannels asserts that exactly 3 input channels are provided.
4. Aggregate Operation Input Count: CreateChannelsAggregateOperation asserts that at least 2 input channels are provided (assertion message says "at least 1" but checks 1 < inputChannels.Count).
5. File Overwrite Safety: CreatePersistentInformationObject deletes any existing file at the target filepath before creating a new persistent channel, using GC.Collect() followed by FileUtils.DeleteFileOrMove.
6. Engineering Units Padding: When persisting engineering units, the string is padded to even length for word-alignment if its length is odd.

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4. Dependencies

This Module Depends On:

• DTS.Common.Enums.Sensors - For SensorConstants (δ and D0 values)
• DTS.Common.Utilities.Logging - For APILogger.Log
• DTS.Common.Utils - For FileUtils
• DTS.Serialization - For SliceRaw.File format handling
• DTS.Slice.Control - Unclear specific usage (imported but no direct reference visible)
• DTS.Common - For Constants.ADC_MIDPOINT, ZeroMethodType
• DTS.Common.Events - For PageErrorEvent, PageErrorArg
• DTS.Common.Calculations - For HeadInjuryCriterion
• DTS.Common.Utilities.Math.Nhtsa - For Integration, Differentiation
• Prism.Ioc - For ContainerLocator
• Prism.Events - For IEventAggregator
• Test.Module namespace - For Channel, CalculatedChannel, AnalogInputChannel
• Event.Module namespace - For Channel, AnalogInputChannel

What Depends On This Module:

• Unclear from source alone - No consumers are shown in this file.

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5. Gotchas

Critical Bugs Identified:

1. Copy-Paste Error in PerformCalculation (line ~378):

   var stepRPot1 = Convert.ToInt32(Math.Ceiling(indexAtCurrentTimeIRTracc) - actualIndexAtCurrentTimeIRTracc);
   

   Uses indexAtCurrentTimeIRTracc instead of indexAtCurrentTimeRPot1. This causes incorrect interpolation for the R-Pot1 channel.

2. Assignment Instead of Subtraction in PerformCalculation (line ~403):

   incrementRPot2 = (valueRPot2AtPoint = rPot2EUData[actualIndexAtCurrentTimeRPot2 - 1]) / rateRPot2;
   

   This is an assignment (=) inside parentheses, overwriting valueRPot2AtPoint, when it should be a subtraction (-).

3. Unused Variable in PerformCalculationsAggregate (line ~151):

   var timeAtIndex =
   

   Variable is declared but never assigned or used. This is a syntax error or incomplete implementation.

Non-Obvious Behaviors:

4. Debug/Test Data Injection: The method calls DiskUtility.ReplaceDataIfNeeded(ref irTraccEUData, "DISPLEU.txt") and similar for other channels. This appears to be a debug feature that can override channel data from disk files. Production behavior is unclear.

5. Explicit GC.Collect() Call: In CreatePersistentInformationObject, GC.Collect() is called before file deletion to handle file locks. This is a heavy operation that may cause performance issues.

6. ScaleEuData Logic Appears Inverted: When max > short.MaxValue, the scale factor calculation scaleFactor = max / short.MaxValue produces a value ≥ 1, which would amplify data that's already too large, potentially causing overflow when casting to short.

7. HIC Unit Conversion: For HIC calculations, if engineering units are not "g", the code multiplies by 9.80665 to convert from m/s² to g's. This assumes the input is in m/s², which may not always be true.

8. Commented-Out Code: There is a commented-out DeleteChannelFile method and associated logic for deferred file deletion, suggesting historical changes to file handling behavior.