[LSST|dm-users 638] Re: Detection and Measurement of Postage Stamp

[Will Dawson]

Jim,

That did the trick! Is there a manual on how to use the doxygen documentation :). I am finding it difficult to navigate the doxygen documentation and that is even with a basic understanding of image detection an measurement procedures. 

Thank you,
Will

> On May 11, 2015, at 3:00 PM, Jim Bosch <jbosch at astro.princeton.edu> wrote:
> 
> I think this should be just a matter of setting
> 
> detectSourcesConfig.reEstimateBackground = False
> 
> 
> 
> Jim
> 
> 
> 
> On Mon, May 11, 2015 at 5:41 PM, Will Dawson <will at dawsonresearch.com <mailto:will at dawsonresearch.com>> wrote:
> 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
> 
> 
>  <28x28stamp.png>
> 
> ---------------------------------------------------------------------------
> 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 <http://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 <http://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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