| Re: Apply a shapefile to raster images in IDL [message #41327 is a reply to message #41289] |
Fri, 08 October 2004 11:23   |
envi35
Messages: 8
Registered: October 2004
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Junior Member |
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Hi Everyone,
Thank you very much for your reply. I've taken Lorenzo's suggestion,
and it works really well. This is a great group, especially to a
novice... Though just began to use IDL a couple of weeks ago, I found
it is a golden mine, worthy to dig hard :-(.
Best Regards to all!
Jenny
lbusett@yahoo.it (Lorenzo Busetto) wrote in message news:<e4da268.0410070408.60d07040@posting.google.com>...
> Hi Jenny,
>
> If your images are all of the same size I think that you can solve
> your problem simply by using ENVI.
>
> 1: Open one of your images and load it in a display
> 2: Convert your shapefile to an ENVI vector file (EVF) by clicking
>> Vector > Open Vector File > Shapefile
> 3: Load your vector on the display where you have loaded your
> image (In the "available vectors list" select the vector, then click
> on "load" and then on "Diplay# (your_display)"
> 4:In the "Vector Parameters" window that appears, select "File >
> Export active layer to ROI"
> 5: Select "basic tools > masking > build mask" and select your
> display
> 6: Select "Options > Import ROIS", then select the ROI you created
> from your vector and click on "OK". Next, choose a name for the mask
> file that you want to create and click on "Apply". Now, in the
> "available bands list you should see a new image, which has value 0
> outside the vector and 1 inside it.
> 7: Now, you can use this "0-1" image as a mask for your image. Go
> to Basic tools > apply mask. Select one of the images that you want to
> mask, then click on "Select mask band" and select the mask image.
> Click on "OK".
>
> If you have many images and you don't want to repeat n-times the
> last step you can use an IDL procedure that automatically opens the
> images and apply the mask on each one.
> I think that something like this should work: it's a simple
> modification of the example program that you can find on the ENVI
> User's guide.
>
> pro multiple_mask
>
> ; Select input files (Select all your images)
>
> files_list = dialog_pickfile(/READ,title ='Select input$
> files',/multiple_files)
>
> ; Select the mask File
>
> mask_file = dialog_pickfile(/read, title = 'Select Mask File')
> envi_open_file, mask_file, r_fid=m_fid
>
> ; Count the number of files
>
> num_files = N_elements (files_list)
>
> for count = 0, num_files-1 do begin
>
> ; Selects the n- file. Output file name is
> "input_file_name"+"-masked"
>
> in_file = files_list [count]
> out_file =files_list [count]+'-masked'
> envi_open_file, in_file, r_fid=fid
> if (fid eq -1 or m_fid eq -1) then return
>
>
> ; get some useful information and set the output filename.
> envi_file_query, fid, ns=ns, nl=nl, nb=nb, bname=bname
>
> ; Set the keyword parameters
> dims = [-1l, 0, ns-1, 0, nl-1]
> pos = lindgen(nb)
> m_pos = [0]
>
> ; Call the 'doit' to apply the mask
>
> envi_mask_apply_doit, fid=fid, pos=pos, dims=dims,m_fid=m_fid,$
> m_pos=m_pos, value=0, out_name=out_file, in_memory=0, $
> r_fid=r_fid
>
> endfor
>
> end
>
> I hadn't fully tested it, but it should work.
>
> Hope this helps,
>
> Lorenzo
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