Creating word file

[Matt Brown]

Stephane,

It is pretty hard to describe this in a "non-mathematic" way, but...

the first value is the dimension of the pixel in the X dimension - the
fourth is the Y dimension.
if you don't know these, you must at least know the geographic extent of the
image to calculate them.

Assuming that you know the extent of the image - you can subtract the
minimum extent from the maximum, and divide the difference by the
width/height in pixels to get the dimension of that pixel in your map units.

ie,(sorry about the math) (maxXorY - minXorY)/imagewidth = pixeldim

you have to note also that the last two values correspond to the x and y
coordinates of the top left pixel.

Matt

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU]On
Behalf Of Stephane Nicolas
Sent: Monday, January 17, 2005 5:58 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Creating word file


Hi,


 I am trying to produce a world file (.tfw) for my tif image for use with
php/map server. The image is x pixels by y pixels. I am unsure what the
values would be for the first and 4 value.

 ?

 0

 0

 ?

 90

 -180

 All the help on the internet has not made it clear to me.

 I will appreciate a "non-mathematic" help....not that clever!

s.