DM-11456 revise jointcal doc and write example for new photometry model #46
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Aug 29, 2017
| \begin{document} | ||
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| \maketitle | ||
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| \abstract{The jointcal package aims at optimizing simultaneously |
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Suggest: "The jointcal package simultaneously optimizes... images. In principle and often in practice, this approach produces..."
| simultaneous astrometry functionality is fulfilled by ``SCAMP''. The | ||
| code we describe here has similar aims, but follows a slightly | ||
| different route. It is meant to be used within the LSST software | ||
| stack framework. } |
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Is "stack framework" a standard phrasing? Or is it just "LSST software stack?"
doc/jointcal.tex
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| plotting tools. | ||
| optimal in a statistical sense. | ||
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| This package performs a least-square fit to a set of images. Since |
doc/jointcal.tex
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| This package performs a least-square fit to a set of images. Since | ||
| it aims at statistical optimality, we maximize the likelihood of the | ||
| measurements with respect to all unknown parameters required to describe | ||
| the data. These parameters consists mostly in two sets: the position |
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Suggest: These parameters are mostly in two sets: the position on the sky of the objects in common between images, and...
doc/jointcal.tex
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| ours: it does not optimize over the position of common objects but | ||
| rather minimizes the distance between pairs of transformed measurements | ||
| of the same object. This approach is not a maximum likelihood optimization, | ||
| and hence is likely sub-optimal statistics wise. We do not know how |
doc/jointcal.tex
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| mapping scaling, which is very well determined from the beginning. | ||
| However, small changes of scaling can lead to the $\chi^{2}$ increasing | ||
| between iterations. This is why we provide the \ClName{AstrometryModel::freezeErrorScales} | ||
| which allows one to uses for there on the \textit{current} state of |
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"to uses for there": needs to be rehashed.
doc/jointcal.tex
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| is in practice obtained using the routine \ClName{Gtransfo::transformPosAndErrors} | ||
| which is attached to the projector. The derivative of the reference | ||
| residual $R_{j}^{r}$ with respect to the \ClName{FittedStar} position | ||
| $F_{j}$ (see eq. \ref{eq:ref_res}), is just the $2\times2$ matrix |
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equation reference was broken in my build; please verify
doc/jointcal.tex
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| and eventually to offset parameters in the \RoutineName{AstrometryFit::OffsetParams}. | ||
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| Since the indexing of parameters is done dynamically, it is straightforward | ||
| to only fit a subset of parameters. this is why the routine \RoutineName{AstrometryFit::AssignIndices} |
doc/jointcal.tex
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| \section{Fitting the transformations between a set of images} | ||
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| Some applications require to determine transformations between images |
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suggest: require determination of transformations
doc/jointcal.tex
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| one just avoids to call \RoutineName{Associations::CollectRefStars}. | ||
| \item One chooses polynomial mappings for all Calexp but one which will | ||
| serve as a reference and have a fixed identity mapping. The distortion | ||
| model \ClName{SimplePolyModel} allows to do that. |
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September 1, 2017 19:51
Move images into separate directory fix image link in original TeX
Exported new version of TeX from LyX
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I imported the text into LyX to edit it, moved some sections around, and generalized most of the math involving the minimization. Primary changes are to the abstract and sections 3.1, 3.2, 3.6, 3.7, 3.8., plus moving the Associations section after the math. Many other sections need work (especially now that photometry is implemented), but the above changes will help me implement the new photometry model, plus they I feel they make the math overall much clearer.