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Re: extract circle from data with idl [message #94787 is a reply to message #94786]

Thu, 12 October 2017 07:27

Markus Schmassmann
Messages: 129
Registered: April 2016

Senior Member

On 10/12/2017 02:10 PM, termybel@gmail.com wrote:
> Thanks to answer but I have a probelm.
>
> You puth this: if n_elements(li) ne 1 then message, 'not exactly 1 contour'
>
> and my program say: not exactly 1 contour
>
> How I can solve it?
>
> If I ask in idl " help,/str,li" and the answer is:
>
> Structure CONTOUR_DBL_PATH_STRUCTURE, 6 tags, length=24, data length=20:
> TYPE BYTE 1
> HIGH_LOW BYTE 1
> LEVEL INT 0
> N LONG 7
> OFFSET LONG 0
> VALUE DOUBLE 9.0000000
>
> and for " help,/str,lines"
> LINES DOUBLE = Array[2, 5447]
>
> My contour isn't a perfect circle. Maybe is this the problem?
>
> This is my program where the image is a flat field panel minus dark:
>
> file_ff1='ff_100s_3.fits' ;immagine
> immagine_ff1=readfits (file_ff1, header1) ; leggo l'immagine del flat field panel
> file_dark='ff_100s_dark_3.fits' ;immagine
> immagine_dark=readfits (file_dark, header1) ; leggo l'immagine della dark
>
> n=100. ; secondi di esposizione dell'immagine
> ffp=(immagine_ff1-immagine_dark)/n
>
> ; contour per selezionare soglie di equivalore
>
> speriamo=fltarr(2048,2048) ; creo una matrice 2048x2048
> dimensioni=size(speriamo,/dimensions)
> cubo=where(ffp lt 9.5 or ffp gt 10)
>
>
>
> wrong_matrix=array_indices(dimensioni, cubo,/dimensions)
> indxw=reform(wrong_matrix(0,*))
> indyw=reform(wrong_matrix(1,*))
> ;ffp(indxw,indyw)=0.
> ;c = CONTOUR(ffp, dimensions=[512,512], Title='prova cubo')
>
> ; DATA being the data to be contoured
> level=9
> contour, smooth(ffp(250:1700, 250:1700),3), path_info=li,closed=1 , path_xy=lines, /path_data_coord, levels=[level], /path_double
> ; lix=lines(0,*)
> ; liy=lines(1,*)
> ; liyd=deriv(lix,liy)
> ;ind=where(abs(liyd) le 0.0001)
>
> if n_elements(li) ne 1 then message, 'not exactly 1 contour'
>
>
> cont_obj =obj_new('IDLanROI',lines)
> void= cont_obj.ComputeGeometry(centroid=center)
> ;fit_ellipse(
> print, center[0:1]
>
> end

contour, smooth(ffp(250:1700, 250:1700),3), path_info=li,closed=1 , $
path_xy=lines, /path_data_coord, levels=[level], /path_double
contour, smooth(ffp(250:1700, 250:1700),3), levels=[level]
; shows you there are more than 1 contour,
; you need to identify the correct one
; often the best is the longest
void=max(li.n,j)
line=[*,li[j].offset+lindgen(li[j].n)]
plot, line[0,*],line[1,*]
cont_obj =obj_new('IDLanROI',line)

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[Message index]

		extract circle from data with idl By: termybel on Wed, 11 October 2017 05:23
		Re: extract circle from data with idl By: Markus Schmassmann on Wed, 11 October 2017 05:41
		Re: extract circle from data with idl By: termybel on Thu, 12 October 2017 05:10
		Re: extract circle from data with idl By: Markus Schmassmann on Thu, 12 October 2017 07:27
		Re: extract circle from data with idl By: termybel on Sun, 15 October 2017 08:43
		Re: extract circle from data with idl By: termybel on Sun, 15 October 2017 09:08
		Re: extract circle from data with idl By: Markus Schmassmann on Mon, 16 October 2017 02:20
		Re: extract circle from data with idl By: termybel on Mon, 16 October 2017 03:23
		Re: extract circle from data with idl By: Helder on Wed, 11 October 2017 05:47

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