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Propose cep3: remove image parameters in camera frame
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...veloper-guide/ceps/proposed/cep-003-remove-image-parameters-in-camera-frame.rst
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CEP 3 - Dropping support for image parameters in CameraFrame | ||
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* Status: draft | ||
* Discussion: NA | ||
* Date accepted: NA | ||
* Last revised: 2023-09-22 | ||
* Author: Maximilian Linhoff | ||
* Created: 2023-09-22 | ||
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Abstract | ||
======== | ||
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Currently, ctapipe supports computing all image parameters in two variants: | ||
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* Using a ``CameraGeometry`` where pixel coordinates are expressed in ``CameraFrame``, i.e. | ||
in length units (most commonly meters) on the camera focal plane. | ||
* Using a ``CameraGeometry`` where pixel coordinates are expressed in ``TelescopeFrame``, i.e. | ||
in angular units (most commonly degree) on sky. | ||
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We propose to drop support for the first, to simplify code in multiple places and reduce | ||
possibility for confusing the two similar variants of the image parameters. | ||
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The overhead of supporting both ``TelescopeFrame`` and ``CameraFrame`` representations | ||
of the image parameters is quite significant, as it e.g. requires dealing with both | ||
possible definitions in all Hillas-style dl2 reconstructors. | ||
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Advantages of computation in TelescopeFrame | ||
=========================================== | ||
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Computing the image parameters in ``TelescopeFrame`` – angular units on the sky – | ||
has the following advantages: | ||
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* Parameters are easier to compare across different telescope types. | ||
* Pointing corrections can directly be applied in the conversion from ``CameraFrame`` | ||
to ``TelescopeFrame`` and are then automatically included in the image parameters, | ||
which is much more straight forward than trying to correct image parameters that | ||
are affected to different degrees after they have been computed. | ||
* Conversion from ``CameraFrame`` to ``TelescopeFrame`` will include any necessary | ||
special handling of the curved cameras of dual mirror telescopes. | ||
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Previous discussions | ||
==================== | ||
* Issue discussing the removal of the camera frame image parameters: `#2061 <https://github.com/cta-observatory/ctapipe/issues/2061>`_ | ||
* Original issue for introducing the computation of image parameters in telescope frame: `#1090 <https://github.com/cta-observatory/ctapipe/issues/1090>`_ | ||
* Pull Request implementing image parameters in telescope frame, also setting it as the default: `#1591 <https://github.com/cta-observatory/ctapipe/pull/1591>`_ | ||
* Adapting the reconstructors to also work with image parameters in telescope frame: `#1408 <https://github.com/cta-observatory/ctapipe/pull/1408>`_ |