| Re: Overlaying a contour on a small image [message #58979] |
Fri, 29 February 2008 12:31 |
wlandsman
Messages: 743
Registered: June 2000
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Senior Member |
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On Feb 29, 1:41 pm, David Fanning <n...@dfanning.com> wrote:
> Isn't this what you want:
>
> im = dist(9)
> thispostion = [0.1, 0.1, 0.9, 0.9]
> TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
> /NOINTERP, /ERASE
> contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
> scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0, 9)
>
I don't think any type of scaling is going to work. (The above
example does not match the contour overlay with the single high
pixel.) The point is that there really is no contour information at
the half-pixel edges, since contours depend on the change between
pixels. (You can display an image of 1 pixel, but you can't contour
1 pixel.) The program sent by Paolo (thanks!) works by not
displaying the outer half pixel where there is no contour
information. I actually like this approach.
The ISOCONTOUR routine looks like it could be used to extrapolate
contours to the outer half pixel, perhaps in an easier way than the
PATH_XY keyword to CONTOUR.
Cheers, --Wayne
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| Re: Overlaying a contour on a small image [message #58984 is a reply to message #58979] |
Fri, 29 February 2008 11:15  |
pgrigis
Messages: 436
Registered: September 2007
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Senior Member |
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Just trying it out, using pg_plotimage
http://hea-www.harvard.edu/~pgrigis/idl_stuff/pg_plotimage.p ro
;linear test array, easier to deal with than dist
a=[[0.,1,2,1,0],[1,2,3,2,1],[2,3,4,3,2],[1,2,3,2,1],[0,1,2,1 ,0]]
loadct,5
pg_plotimage,a,findgen(5),findgen(5)
contour,a,/over,levels=[0.5,1.5,2.5,3.5],color=0
(The contours should have a vertex exactly at the pixel
boundaries by construction of the image)
The half pixel at the boundary is missing however.
Paolo
David Fanning wrote:
> David Fanning writes:
>
>> Wayne Landsman writes:
>>
>>> Does anyone have a routine to overlay a contour plot on a small image
>>> that is both accurate and aesthetically pleasing?
>>
>> Isn't this what you want:
>>
>> im = dist(9)
>> thispostion = [0.1, 0.1, 0.9, 0.9]
>> TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
>> /NOINTERP, /ERASE
>> contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
>> scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0, 9)
>
> I don't know. What do you think of this:
>
> im = dist(9)
> im[2,2] = 15
> im[4:5, 4:5] = 10
> thispostion = [0.1, 0.1, 0.9, 0.9]
> TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
> /NOINTERP, /ERASE
> contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
> scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0,9), $
> level = 6
>
> isocontour, im, v, c, c_value = 6
> Plots, v[0,0:6]+0.5, v[1,0:6]+0.5, color=fsc_color('dodger blue')
> Plots, v[0,7:*]+0.5, v[1,7:*]+0.5, color=fsc_color('dodger blue')
>
>
> Note how I have to add a half pixel to the ISOCONTOUR to get
> it anywhere near where I want it. Weird.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming: http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Overlaying a contour on a small image [message #58985 is a reply to message #58984] |
Fri, 29 February 2008 11:06 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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David Fanning writes:
> Wayne Landsman writes:
>
>> Does anyone have a routine to overlay a contour plot on a small image
>> that is both accurate and aesthetically pleasing?
>
> Isn't this what you want:
>
> im = dist(9)
> thispostion = [0.1, 0.1, 0.9, 0.9]
> TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
> /NOINTERP, /ERASE
> contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
> scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0, 9)
I don't know. What do you think of this:
im = dist(9)
im[2,2] = 15
im[4:5, 4:5] = 10
thispostion = [0.1, 0.1, 0.9, 0.9]
TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
/NOINTERP, /ERASE
contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0,9), $
level = 6
isocontour, im, v, c, c_value = 6
Plots, v[0,0:6]+0.5, v[1,0:6]+0.5, color=fsc_color('dodger blue')
Plots, v[0,7:*]+0.5, v[1,7:*]+0.5, color=fsc_color('dodger blue')
Note how I have to add a half pixel to the ISOCONTOUR to get
it anywhere near where I want it. Weird.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Overlaying a contour on a small image [message #58986 is a reply to message #58985] |
Fri, 29 February 2008 10:41 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Wayne Landsman writes:
> Does anyone have a routine to overlay a contour plot on a small image
> that is both accurate and aesthetically pleasing?
Isn't this what you want:
im = dist(9)
thispostion = [0.1, 0.1, 0.9, 0.9]
TVIMAGE, bytscl(im), POSITION=thisPosition, /KEEP_ASPECT_RATIO, $
/NOINTERP, /ERASE
contour,im, Position=thisPosition,/xsty,/ysty,/noerase,$
scale_vector(findgen(9), 0, 9), scale_vector(findgen(9), 0, 9)
You can find SCALE_VECTOR here:
http://www.dfanning.com/programs/scale_vector.pro
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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