Generate World Files for ECW?

RE: Generate World Files for ECW?

hUbS — Wed, 19 Feb 2014 12:42:13 GMT

Hi Mathieu,

Looking into it a bit further, with no rotation Line 5 and 6 Correspond to the X and Y coordinate of the 'Center' of the 'Top Left' pixel so we have...

WRL1 = PixelSize.X

WRL2 = 0

WRL3 = 0

WRL4 = - PixelSize.Y

WRL5 = Origin.X + PixelSize.X / 2

WRL6 = Origin.Y + ('Number of Pixels.Y' * PixelSize.Y) - PixelSize.Y / 2

Mike

RE: Generate World Files for ECW?

Mathieu St-pierre — Sun, 16 Feb 2014 20:19:49 GMT

Hi Mike,

If the ECW has no affinity or rotation it is quite simple to create the World File by hand.

A world file has is made of 6 numbers, each on a different line, which can be deduced from the information in the Element Information dialog as followed

Line 1 : Pixel size x

Line 2 : 0

Line 3 : 0

Line 4 : -Pixel size y (note the minus sign)

Line 5 : Origin x

Line 6 : Origin y + Number of pixel y * Pixel size y

So the world file for the data in the dialog below is :

0.181126315789
0
0
-0.181130229145
247892.619282726110
6270532.284671764800

Note that if the rotation or affnity is not equal to 0 it is still possible to deduce the numbers, but the computations are more complicated.

Also note that the number in a World File should be in meters.

Thanks,

Mathieu

RE: Generate World Files for ECW?

hUbS — Fri, 14 Feb 2014 16:08:27 GMT

Thanks Pascal.

That's what I did. The problem is ECW's can be several Gb in size, converting to another format can take a long time.

Mike

RE: Generate World Files for ECW?

Pascal Cloutier — Fri, 14 Feb 2014 14:25:35 GMT

Hi Mike,

Here is a workaround you can try to create sister files for your ECW files in the current versions of Raster Manager.

1) Save As the ECW file to "Tag Image File Format". In the "Raster Save As Settings" dialog, set "Sister File" to "World File". If you don't want to do it manually for each raster you need to convert, you can also use Raster Manager's "Batch Convert". The TIF files should be created in the same folder as the ECW files.

2) Once the TIF files and their associated TFW files are created, delete all the TIF files.

3) Rename the extension of the TFW files to EWW. Again, if you don't want to do it manually, you can easily find apps online that will rename the files for you (e.g. ReNamer).

I'll file a request on your behalf in our bug tracking system to ask for an option to generate a sister file for ECW files.

Pascal