[LSST|dm-users 636] Detection and Measurement of Postage Stamp

[Will Dawson]

I am trying to use DM Stack detect and analyze in object in a small postage stamp (see attached example, log scale). I know I can use lsst.afw.detection.Threshold() with lsst.afw.detection.FootprintSet() to create a footprint for the detected object. But I also (first) tried lsst.meas.algorithms.SourceDetectionTask(config=detectSourcesConfig, "other args") with config set as:

detectSourcesConfig   = measAlg.SourceDetectionConfig(thresholdType='value’)
or
detectSourcesConfig   = measAlg.SourceDetectionConfig(thresholdType='value',thresholdValue=0)

and got the error at the end of this email. I am not entirely sure how to parse this error statement, but if I had to guess: no objects are being detected because it is trying to estimate the background based on this stamp which contains primary just the object thus when it does image - background there is nothing above threshold left to detect. Or it chokes when trying to estimate the background.

Is there an option to run lsst.meas.algorithms.SourceDetectionTask with the background estimation/ subtraction process turned off? For example when detecting objects on an image that already has the background subtracted. Perhaps the only option is to stick with the detection.FootprintSet method. 

Thanks,
Will


 

---------------------------------------------------------------------------
InvalidParameterError                     Traceback (most recent call last)
<ipython-input-66-d08d86b9540f> in <module>()
      2 # catalog atually stores stuff)
      3 table   = afwTable.SourceTable.make(schema)
----> 4 catalog = detect.makeSourceCatalog(table, exposure, sigma=3)

/Users/dawson/lsst/DarwinX86/pipe_base/10.0+2/python/lsst/pipe/base/timer.pyc in wrapper(self, *args, **keyArgs)
    116         logInfo(obj = self, prefix = func.__name__ + "Start")
    117         try:
--> 118             res = func(self, *args, **keyArgs)
    119         finally:
    120             logInfo(obj = self, prefix = func.__name__ + "End")

/Users/dawson/lsst/DarwinX86/meas_algorithms/10.0+2/python/lsst/meas/algorithms/detection.pyc in run(self, table, exposure, doSmooth, sigma, clearMask)
    313             raise ValueError("Table has incorrect Schema")
    314         fpSets = self.detectFootprints(exposure=exposure, doSmooth=doSmooth, sigma=sigma,
--> 315                                        clearMask=clearMask)
    316         sources = afwTable.SourceCatalog(table)
    317         table.preallocate(fpSets.numPos + fpSets.numNeg) # not required, but nice

/Users/dawson/lsst/DarwinX86/pipe_base/10.0+2/python/lsst/pipe/base/timer.pyc in wrapper(self, *args, **keyArgs)
    116         logInfo(obj = self, prefix = func.__name__ + "Start")
    117         try:
--> 118             res = func(self, *args, **keyArgs)
    119         finally:
    120             logInfo(obj = self, prefix = func.__name__ + "End")

/Users/dawson/lsst/DarwinX86/meas_algorithms/10.0+2/python/lsst/meas/algorithms/detection.pyc in detectFootprints(self, exposure, doSmooth, sigma, clearMask)
    443             fpSets.background = bkgd
    444             self.log.log(self.log.INFO, "Resubtracting the background after object detection")
--> 445             mi -= bkgd.getImageF()
    446             del mi
    447 

/Users/dawson/lsst/DarwinX86/afw/10.0+3/python/lsst/afw/math/mathLib.pyc in getImageF(self, *args)
   5736         getImageF(Background self) -> boost::shared_ptr< lsst::afw::image::Image< float > >
   5737         """
-> 5738         return _mathLib.Background_getImageF(self, *args)
   5739 
   5740     def getImageI(self, *args):

InvalidParameterError: 
  File "src/math/Interpolate.cc", line 60, in std::pair<std::vector<double>, std::vector<double> > lsst::afw::math::(anonymous namespace)::recenter(const std::vector<double> &, const std::vector<double> &)
    You must provide at least 1 point {0}
  File "src/math/BackgroundMI.cc", line 196, in void lsst::afw::math::BackgroundMI::_setGridColumns(const Interpolate::Style, const lsst::afw::math::UndersampleStyle, const int, const std::vector<int> &) const
    setting _gridcolumns {1}
lsst::pex::exceptions::InvalidParameterError: 'You must provide at least 1 point {0}; setting _gridcolumns {1}'

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