| interpolation for resizing [message #64168] |
Tue, 02 December 2008 14:29  |
bryan.s.hong
Messages: 12
Registered: November 2008
|
Junior Member |
|
|
I have a 100 X 100 spatial image to be resized to 1000*1000.
The data of this image is surface temperature and includes some part
of ocean.
Because I want to exclude data of ocean area during interpolation, I'm
trying to resize it using "interpolate".
But I cannot understand the IDL help pages for the 'interpolate'.
Could anyone help me with a simple command line for this job? Thanks.
- Bryan
|
|
|
|
| Re: interpolation for resizing [message #64198 is a reply to message #64168] |
Sun, 07 December 2008 08:57  |
ben.bighair
Messages: 221
Registered: April 2007
|
Senior Member |
|
|
On Dec 5, 11:04 am, "Jean H." <jghas...@DELTHIS.ucalgary.ANDTHIS.ca>
wrote:
>> I guess you didn't read my question properly (although I maybe didn't
>> have to ask it in this thread to avoid this, but I didn't want to make
>> a new thread because of David's post several days ago). I'm not trying
>> to resize anything. I just want the -999 or NaN (I make them with !
>> Values.F_NAN option btw.) values to have a value in the b array that
>> is calculated by interpolation (for instance: the IDW of the
>> surroundig pixels in a 3x3 window).
>
>> So sorry for the mixup and thanks if you guys still feel like finding
>> a solution for this.
>
> Hi,
> ah, now you give more information... a 3*3 window, and IDW... well, the
> "do it yourself" solution is the easiest... You can put that in a
> function or else.
>
Hi,
I am not sure if I am following this new twist (isn't IDW a type of
root beer?) I should point out that IDL's built in GRIDDATA routine
will accept polygonal breaks in interpolation (such as a polygon
describing the break between land and water). I have found that it
works well even if it is a pain to develop the polygons. That might
be just what you are looking for. It is worth getting over the hump
to learn the ins-and-outs of GRIDDATA if you will be doing this kind
of thing often.
Cheers,
Ben
|
|
|
|
| Re: interpolation for resizing [message #64207 is a reply to message #64168] |
Fri, 05 December 2008 08:04 |
Jean H.
Messages: 472
Registered: July 2006
|
Senior Member |
|
|
> I guess you didn't read my question properly (although I maybe didn't
> have to ask it in this thread to avoid this, but I didn't want to make
> a new thread because of David's post several days ago). I'm not trying
> to resize anything. I just want the -999 or NaN (I make them with !
> Values.F_NAN option btw.) values to have a value in the b array that
> is calculated by interpolation (for instance: the IDW of the
> surroundig pixels in a 3x3 window).
>
> So sorry for the mixup and thanks if you guys still feel like finding
> a solution for this.
Hi,
ah, now you give more information... a 3*3 window, and IDW... well, the
"do it yourself" solution is the easiest... You can put that in a
function or else.
pro test_interpol
nx=10
ny=10
data = findgen(nx,ny)
data[2,2] = !VALUES.F_NAN
data[6,6] = !VALUES.F_NAN
;print,data
badIdx = where(finite(data) eq 0, countBad)
print,'Bad index: ', badIdx
;badNeighbors = rebin(badIdx, 8 ,countBad)
badNeighbors = transpose(rebin(badIdx, countBad,8))
;Get the index of the cells in the Moore neighborhood of each bad
;pixel (you deal with the pixels on the border...)
badNeighbors[0,*] -= 1
badNeighbors[1,*] += 1
badNeighbors[2,*] -= nx
badNeighbors[3,*] -= nx-1
badNeighbors[4,*] -= nx+1
badNeighbors[5,*] += nx
badNeighbors[6,*] += nx-1
badNeighbors[7,*] += nx+1
print, 'Neighbors of bad index: ',badNeighbors
goodValue = (data[badNeighbors[0,*]] + data[badNeighbors[1,*]] +$
data[badNeighbors[2,*]] + data[badNeighbors[3,*]]+$
data[badNeighbors[4,*]] + data[badNeighbors[5,*]] +$
data[badNeighbors[6,*]] +data[badNeighbors[7,*]])/8
;Adjuste the equation yourself.
print,'Interpolated values: ', goodValue
data[badIdx] = goodValue
print,'The new data: ', data
end
Jean
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
