| Label_region and Erosion [message #13283] |
Tue, 03 November 1998 00:00  |
lbryanNOSPAM
Messages: 21
Registered: July 1998
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Junior Member |
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I'm sending the group some sample code (it hasn't been overly debugged
or documented, but should work) I've written with some of David
Fanning's and Struan (Gray)'s code as a base. I'm looking to create
a multi-surface plot, from a 2-D data array. The procedure is
straightforward and works great on the simple data set I've set up. I
need, however, something that can handle some ambiguous and noisy
surfaces. My first question is how do I find out what algorithm is
used in LABEL_REGION? Since I do not see this function in the library,
I assume it is written in C somewhere. I'm trying to use it to detect
surfaces in my target volume and am having mixed results. How does it
decide what is a unique surface and what is only a bump on a surface?
Thanks for any info you can pass along.
Also, I've had a suggestion to use morphologic filters, erode and
dilate. They look helpful for my goal. From the IDL books, I think I
see how they work on binary applications, but the greyscale use is
confusing me. Does anyone have an example of how they work on this
kind of an application?
Lastly, I wan't to apply a median filter (and possible other filters)
to some sections of my surfaces but not others (all irregular shapes).
I imaging I'll have to write my own procedure where I pass over my
data with a filter and a masking function to exclude certain areas.
Has anyone already done this? Am I missing an easy way to do this?
Thanks in advance. Here's my code (messy as it is!).
Lisa Bryan
PRO MULTI_SURF_EXAMPLE
plane = fltarr(100,100)
plane(55:85,20:50) = dist(31)+10
plane(5:15,40:70) = (findgen(341))/100+30
plane(30:35,5:75) = (findgen(426))/100+20
plane(75:95,75:95) = (findgen(441))/100+25
shade = dist(100)
MULTI_SURF, PLANE, SHADE, MAXSHADE = 70, b
END
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
PRO MULTI_SURF, bottdepth, bottshade, maxshade = maxshade,$
b
;+
; NAME:
; MULTI_SURF
; PURPOSE:
; To seperate a single surface into multisurfaces and
; plot them all to a single 3-D SHADE_SURF plot.
;
; CALLING SEQUENCE:
; MULTI_SURF, bottdepth, bottshade
;
; INPUTS:
; bottdepth is a 2d array that is the depth of each pixel
; bottshade is a 2d array with the same dimensions as bottdepth
; which shows the relative intensity of each pixel
;
; INPUT KEYWORDS:
; MAXSHADE: This is the maximum value to be included in the
; shades which are to be plotted over the surface.
;
;
; OUTPUTS:
;
;
; NOTES:
;
; REVISION HISTORY:
; Written E.L. Bryan Nov. 1998
;
; check the dimensions
if (total(size(bottdepth)) ne total(size(bottshade))) then begin
print, 'Depth and Shade arrays must be of the same dimension'
return
endif
image = bottdepth
image = image - min(image) ;set min(image) to 0
szimage = size(image)
b = LABEL_REGION(image,/eight) ;define surfaces in b
h = HISTOGRAM(b, REVERSE_INDICES=r) ;Get population and members of
;each blob.
;set up Z buffer
thisDevice = !D.Name
Set_Plot, 'Z'
Device, Set_Resolution=[szimage(1) > 500,szimage(2) > 400]
;set up axes with no data
surface,image,zrange = [min(image),max(image)],$
min_value = min(image),/nodata
FOR i=0, N_ELEMENTS(h)-1 DO BEGIN ;Select each region
current_surf = image
current_surf(where(b(*) ne i)) = -10 ;place everything but
;current surface below plotted region
shade_surf,current_surf,zrange = [min(image),max(image)],$
min_value = min(image),/noerase, $
shades = bytscl(bottshade,max = maxshade)
;count regions
p = r(r[i]:r[i+1]-1) ;Subscripts of members of region i.
q = image[p] ;Pixels of region i
PRINT, 'Region ', i, $
', Population = ', h[i]
ENDFOR
snapshot = TVRD()
Set_Plot, thisDevice
window,0,xs = szimage(1) > 500,ys = szimage(2) > 400
TV, snapshot
end
Arete Associates
Tucson, Arizona
lbryan@arete-az.com
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