Q: How to read and understand a "world file"

[Martin Hvidberg]

Dear all

I have to be able to read "world files" and write (sorry) mapinfo .tab
files.

Anybody know how a world file (.tfw) are put together, and how to decode
it???

In the future I will most likely need to go the other way, i.e. read
.tab files and write world files. Therefore any factual information on
the subject(s) are mostly welcomed

Best regards & Thanks in advance

Martin Hvidberg
M.Sc. Physical Geography
Danish Forest and Landscape Research Institute, GIS lab.
Hørsholm Kongevej 11
DK-2970 Hørsholm
DENMARK
Pho.: +45 45 76 32 00 (direct +45 45 17 83 27)
Fax.: +45 45 76 32 33 (direct +45 45 76 57 56)
Email.: m...@fsl.dk
Url: http://www.fsl.dk/eng/

[Sergey]

Martin Hvidberg <Mar...@Hvidberg.net> wrote in article
<37D3BDA9...@Hvidberg.net>...

> Dear all
>
> I have to be able to read "world files" and write (sorry) mapinfo .tab
> files.
>
> Anybody know how a world file (.tfw) are put together, and how to decode
> it???

Here are .tab and .tfw files for the same image. Both formats are quite
simple, so i think you'll manage to decode them. If not, i can find
descriptions, but later (maybe tomorrow).

Cheers,
Serguey.

p.s. First line in twf file is size of a pixel in coordinate units (i.e. in
meters or decimal degrees)

[Stjernholm, Michael]

Hi Martin
My experience is that you have to consider both a .tfw and a .hdr file in
order to read images, so if you get stuck whe trying to write only a .tfw
then consider to create a header file as well. The item has not be properly
documented in ArcView, so you might consider looking into the ArcInfo manual
on image Integration to find the proper keywords.

Be aware of MapInfo uses coordinates of the outer boundary of the image,
whereas the world file refers to the center of the upper left corner.

Best regards

Michael Stjernholm

Martin Hvidberg <Mar...@Hvidberg.net> wrote in message
news:37D3BDA9...@Hvidberg.net...

> Dear all
>
> I have to be able to read "world files" and write (sorry) mapinfo .tab
> files.
>
> Anybody know how a world file (.tfw) are put together, and how to decode
> it???
>

[Tom Kralidis]

Here's what I came up with, hope it helps.

ESRI .tfw File Format

Used as attribute file associated with corresponding .tif file.

.tfw files consist of 6 lines, denoting the following:

sampleFile.tfw

5.000000000000 (size of pixel in x direction)
0.000000000000 (rotation term for row)
0.000000000000 (rotation term for column)
-5.000000000000 (size of pixel in y direction)
492169.690845528910 (x coordinate of centre of upper left pixel in
map units)
5426523.318065105000 (y coordinate of centre of upper left pixel in
map units)

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Tom Kralidis Geo-Spatial Technologist
Canada Centre for Remote Sensing Tel: (613) 947-1828
588 Booth Street , Room 241 Fax: (613) 947-1408
Ottawa , Ontario K1A 0Y7 http://www.ccrs.nrcan.gc.ca
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