# Add PolyMap transforms to transformFactory.h

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## Details

• Type: Story
• Status: To Do
• Resolution: Unresolved
• Fix Version/s: None
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## Description

I'm looking at some code in obs_subaru

 forwardCoeffs = makeAstPolyMapCoeffs(config.ccdToSkyOrder, config.xCcdToSky, config.yCcdToSky)   # Note that the actual error can be somewhat larger than TolInverse; # the max error I have seen is less than 2, so I scale conservatively ccdToSky = ast.PolyMap(forwardCoeffs, 2, "IterInverse=1, TolInverse=%s, NIterInverse=%s" %  (config.tolerance / 2.0, config.maxIter)) plateScaleAngle = config.plateScale * arcseconds fullMapping = ccdToSky.then(ast.ZoomMap(2, plateScaleAngle.asRadians())) return TransformPoint2ToPoint2(fullMapping) 

And that doesn't seem to be achievable using a makeXXXTransform from src/geom/transformFactory.cc

I'm concerned that HSC was forced to use the internal ast calls, especially ones that use a string to pass arguments to C++, they should be an internal detail. This isn't urgent (I'm only working on the LSST cameras at the moment), but I think that this should be hidden behind a makePolyMapTransform (or some similar name) in transformFactory.cc

## People

• Assignee:
Unassigned
Reporter:
Robert Lupton
Watchers:
Krzysztof Findeisen, Robert Lupton, Russell Owen, Tim Jenness