VERITAS-Observatory · GernotMaier · May 17, 2026 · May 17, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -9,21 +9,39 @@ This changelog is generated using [Towncrier](https://towncrier.readthedocs.io/)
 
 <!-- towncrier release notes start -->
 
-## [v492.0](https://github.com/VERITAS-Observatory/EventDisplay_v4/releases/tag/v492.0) - 2025-11-11
+## [v492.0-rc4](https://github.com/VERITAS-Observatory/EventDisplay_v4/releases/tag/v492.0-rc4) - 2026-05-17
 
-### Bugfixes
+### New Feature
 
-- Fix segmentation fault when exiting on error due to an empty tree in anasum. ([#286](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/286))
-- Limit number of errors printed when reading faulty VBF files to avoid TB large log files. ([#298](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/298))
-- Add cut to wobble offset 0.5 for calculation of MC-derived gamma-ray rates used for BDT cut optimization. ([#314](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/314))
+- Improve DispBDT reconstruction by adding `loss^2` and `loss*dist` as training variables. This improves sensitivity to truncated images. ([#318](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/318))
+- Feature: Machine learning interface for direction reconstruction
 
-### Documentation
+  - Adds an interface to run machine learning models (e.g., scikit-learn).
+  - Provides an example using XGBoost regression trees to estimate directions in camera coordinates.
+  - Introduces a Python environment and a scripts directory to support training and inference.
 
-- Add libtool compile instructions to readme. ([#287](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/287))
-- Improved description of docker image building. ([#292](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/292))
+  The new XGBoost-based training and reconstruction methods estimate the gamma‑ray arrival direction in camera coordinates. They support `DispBDT` and intersection methods, combining image parameters to compute `Xoff`/`Yoff`.
 
-### New Feature
+  Compared to previous approaches that averaged over all `DispBDT` directions, this implementation better handles edge cases (e.g., truncated images).
+
+  ([#322](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/322))
+- Add print out average run zenith angle to `printRunParameter` option `-runinfo`. ([#334](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/334))
+- Improve TMVA interpolation from average zenith to average airmass. ([#336](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/336))
+- Allow to choose energy and direction reconstruction methods:
 
+  ```
+  Stereo reconstruction
+  ---------------------
+  Method ids: 0 (DispBDT), 1 (LT Tables), 2 (XGB stereo)
+  * ENERGYRECONSTRUCTIONMETHOD 0
+  Method ids:  0 (DispBDT), 1 (Intersection Method), 2 (XGB stereo)
+  * DIRECTIONRECONSTRUCTIONMETHOD 0
+  ```
+
+  Consistently use `CData` methods to get variables.
+
+  ([#339](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/339))
+- Improve mscw plotting macro for consistent comparison of different analysis sets. ([#340](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/340))
 - Introduction of average zenith angle calculation per run in VTMVAEvaluator (fAverageZenithPerRun, calculate_average_zenith_angle()). ([#281](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/281))
 - Introduced new functionality for reconstructing events using any three telescopes out of four (primarily for Monte Carlo data and effective area calculations).
   Added new class: `VMeanScaledVariables` for mean scaled variable calculations.
@@ -33,6 +51,32 @@ This changelog is generated using [Towncrier](https://towncrier.readthedocs.io/)
 
 ### Maintenance
 
+- Improve efficiency of IRF calculation (lower storage footprint; introduce possibility to re-calculate all stereo parameters (MSCW, MSCL, emission height, direction, core, energy) on the `mscw_energy` level for 3-telescope events from 4-telescope MC simulations. This is for MC events only and used to simplify and accelerate the analysis required for the generation of effective areas.) ([#293](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/293))
+- - reduced storage impact of `mscw_energy` branch (mostly due to change of doubles to floats; removal of unused variables); reduction is on storage requirements is ~25%.
+  - efficiency improvement in running `mscw_energy` -> 20% faster
+  - fine-tuning of docker build scripts to improve build efficiency
+  - add code to redo stereo reconstruction to `CData.cpp`. Functions are named `reconstruct_3tel_images*`
+  - generalized calculation of MSCW, MSCL, MWR, MWL variables in new classes `VMeanScaledVariables`
+  - allow to recalculate `dispBDTDirection` and `dispBDTEnergy` in `VDispAnalyzer` from values per image
+  - several important improvements and bug fixes in stereo reconstruction code in `VTableLookupDataHandler`:
+  	- `Chi2` from direction reconstruction not correctly filled from `showerpars` trees
+  	- bug fix in setting of `NImages` and selected telescopes for 3-telescope runs (function `fill_selected_images_before_redo_stereo_reconstruction`)
+  - clarified that `Erec` is from `dispBDTEnergy` while `ErecS` is from simple lookup table reconstruction. Change default values for `EnergyReconstructionMethod` to `Erec` (method ID `0`) for `anasum` and `effective area` code.
+  - introduced consistent naming of tree reader support classes. Moved them from `.C` to `.cpp`. Removed obsolete code in these files.
+  - removed `Version` from `CData` class initialize (as it is read from tree doc string).
+  - removal of `CEffFit.h` classes (not used anywhere)
+  - bug fix in SizeSecondMax calculation for 3-tel reconstruction using in `mscw_energy` the `rec_id` option (no image selection was applied)
+  - maintenance and cleanup of obsolete files (see PR #294)
+
+  ([#303](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/303))
+- - minor updates to run with root 6.38.
+  - switch default ROOT docker image to ubuntu
+
+  ([#323](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/323))
+- Change location of ROOT macros from ./macros/VTS to ./macros. ([#330](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/330))
+- Removed deprecated smoothing and interpolation functionality for MVA cut values.
+  Cleaned up unused parameters and obsolete code related to box smoothing and TMVA optimization. ([#336](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/336))
+
 - Update URL for SOFA download. ([#317](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/317))
 - Update SOFA to version 2023-10-11. ([#284](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/284))
 - Changes in tree structure and variable types to reduce size of output trees (mostly due to change of doubles to floats; removal of unused variables); reduction is on storage requirements is ~25%. ([#288](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/288))
@@ -45,3 +89,14 @@ This changelog is generated using [Towncrier](https://towncrier.readthedocs.io/)
 - Introduce towncrier for changelogs. ([#300](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/300))
 - Fix github action worklows to compile Eventdisplay. Add cpp11 workflow. ([#307](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/307))
 - Performance improvements for mscw energy stage. ([#312](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/312))
+
+### Bugfixes
+
+- Fix segmentation fault when exiting on error due to an empty tree in anasum. ([#286](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/286))
+- Limit number of errors printed when reading faulty VBF files to avoid TB large log files. ([#298](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/298))
+- Add cut to wobble offset 0.5 for calculation of MC-derived gamma-ray rates used for BDT cut optimization. ([#314](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/314))
+
+### Documentation
+
+- Add libtool compile instructions to readme. ([#287](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/287))
+- Improved description of docker image building. ([#292](https://github.com/VERITAS-Observatory/EventDisplay_v4/issues/292))
diff --git a/docs/changes/293.maintenance.md b/docs/changes/293.maintenance.md
diff --git a/docs/changes/303.maintenance.md b/docs/changes/303.maintenance.md
diff --git a/docs/changes/318.feature.md b/docs/changes/318.feature.md
diff --git a/docs/changes/322.feature.md b/docs/changes/322.feature.md
diff --git a/docs/changes/323.maintenance.md b/docs/changes/323.maintenance.md
diff --git a/docs/changes/330.maintenance.md b/docs/changes/330.maintenance.md
diff --git a/docs/changes/334.feature.md b/docs/changes/334.feature.md
diff --git a/docs/changes/336.feature.md b/docs/changes/336.feature.md
diff --git a/docs/changes/336.maintenance.md b/docs/changes/336.maintenance.md
diff --git a/docs/changes/339.feature.md b/docs/changes/339.feature.md
diff --git a/docs/changes/340.feature.md b/docs/changes/340.feature.md