Batch Reprojecting images via EASI using REPROJ.EAS

REPROJ.EAS is an EASI script to batch process reprojecting images and at the same time performing a file format conversion. This script support UTM, Lat/Long, SPCS, and user defiend projections such as LCC.

1) Specifying which files to process.

The script uses an ASCII file called filelist.txt which contains the list of files to process. The format of the file is :

<projection file>
<input image file> <output image file>
<input image file> <output image file>
<input image file> <output image file>
...
...
...
<projection file>
<input image file> <output image file>
<input image file> <output image file>
<input image file> <output image file>
...

Here is an example :

c:\data\tom\masterproj.tif
c:\data\tom\pct.tif       c:\data\tom\llpct.tif
c:\data\tom\3band.pix     c:\data\tom\ll3band.tif
c:\data\tom\test1.jpg     c:\data\tom\lltest1.tif

If the line in the filelist.txt file only contains one entry.  This image contains the georeferencing information that the images to be reprorjected will be reprojected to. In the above example, the file "c:\data\tom\masterproj.tif" contains the output projection. Any GDB supported file can be used for the source projection or a new image file can be created using the PCI software.

If the line in the filelist.txt file contains two entries, then the first entry is the input iamge to be reprojected and the second entry is the destination image file.

The filelist.txt file will  have at least one section of input image projection followed by the list of input and output images, one on each line. If projectioning to more than one projection than simply have a section for each different output projection.


2) Specifying the output image type and source directory

The script contains the following lines:

Rem !!!!!!! This must be set to indicate the type of file to export
Rem         and also the directory for the necessary files

sOutputType = "TIF"
sDirectory = NormalizePath( "c:\data\tom\" )

The parameters sOutputType is the output image format and the sDirectory is the directory where the filelist.txt is located.


3) Running the script

To execute the script run EASI by typing EASI at the command prompt.

At the EASI prompt, run the script by typing run <script name> where script name is the path and file name where the script is located. If you place the REPROJ.EAS in your Geomatica_v91\pro directory, you can simply type EASI>r REPROJ at the EASI prompt.

Here is sample output when the script is run:

EASI>run "/data/tom/reproj.eas"
Start conversion process
Set projection : c:\data\tom\masterproj.tif
Reproject files : c:\data\tom\pct.tif       c:\data\tom\llpct.tif
Creating     512P     512L    1C file: c:/data/tom/sSourceTempPix.pix
 Creating segment:  1  [ 150: @@Georeferencing      ]        8 Blocks long
    Converting file : c:\data\tom\pct.tif
    Create new file : c:\data\tom\llpct.tif
Creating     512P     512L    1C file: c:/data/tom/sDestinationTempPix.pix
 Creating segment:  1  [ 150: @@Georeferencing      ]        8 Blocks long
 Creating segment:  2  [ 171: @PseudoColorTable:Pseudo-Color Table]        8 Blo
cks long
Reproject files : c:\data\tom\3band.pix     c:\data\tom\3band.tif
Creating     512P     512L    3C file: c:/data/tom/sSourceTempPix.pix
 Creating segment:  1  [ 150: @@Georeferencing      ]        8 Blocks long
    Converting file : c:\data\tom\3band.pix
    Create new file : c:\data\tom\3band.tif
Creating     512P     512L    3C file: c:/data/tom/sDestinationTempPix.pix
 Creating segment:  1  [ 150: @@Georeferencing      ]        8 Blocks long

4) This script is designed to work to reproject form one coordinate from another.  Often customers will want to use our reproject functionality to change the resolution of their images.  In this case no reprojecting actually happens, only resampling to a larger or smaller pixel size.  In the state that reproj.eas is downloaded, you will not be able to use it to change the pixel size, however, it is possible to hard code it for this purpose to batch resample several images at once.  Here is how you can do this.

For example, using the irvine.pix image file in the PCI Demo directory you can see that this file has a resolution of 30m and a file size of 512 pixels x 512 lines.  To resample this file to get a 60m pixel size (double) you would have an output file half of the existing file size. Your new, resampled file would have a physical size of 256 pixels x 256 lines, which gives you a resolution of 60m.  All you have to do is divide the current resolution by 2 to get your 60m pixel size.  You can do this by manually editing this section of code:

rem Simple check to see if input file exists
    fd = DBOpen(sFileIn, "r")
    if fd < 1 then
        print "-----Error openning file : " + sFileIn
        return
    endif
    nChannels = DBChannels(fd)
    nLines = DBLines(fd)
    nPixels = DBPixels(fd)
    sDataType = DBChanType(fd, 1)
    nPCT = DBNextSeg(fd, "PCT", -1)
    if nPCT > -1 then
        call DBReadPCT(fd, nPCT, PCT)
    endif
    call DBClose(fd)

You must divide (or multiply) the nLines and nPixels values to match those of the desired resolution of your output.  The edited script would look like this:

rem Simple check to see if input file exists
    fd = DBOpen(sFileIn, "r")
    if fd < 1 then
        print "-----Error openning file : " + sFileIn
        return
    endif
    nChannels = DBChannels(fd)
    nLines = DBLines(fd)/2
    nPixels = DBLines(fd)/2
    sDataType = DBChanType(fd, 1)
    nPCT = DBNextSeg(fd, "PCT", -1)
    if nPCT > -1 then
        call DBReadPCT(fd, nPCT, PCT)
    endif
    call DBClose(fd)



If you are using this script to batch several files and change their resolution, your input files must all be the same physical size.


5) If you cannot get this to run, please contact support@pcigeomatics.com for assistance.  We are currently working on adding the batch reproject to our GUI interface in Modeller.