GAT - Ground Altitude File

October 27th, 2005

Gravity Altitude Terrain (GAT), it’s a file that contains every cell altitude.

*	Field	Size		Type	Description
0	Header	6	bytes	Integer	GRAT..
6	Size X	4	bytes	Integer	Size of field
10	Size Y	4	bytes	Integer	Size of field
{	Tiles (Header offset +14)
0	Cell	4	bytes	Float	Left Bottom
4	Cell	4	bytes	Float	Right Bottom
8	Cell	4	bytes	Float	Left Top
12	Cell	4	bytes	Float	Right Top
16	Type	1	bytes	Byte	See below
17	??	3	bytes	Integer	-
}

Tile (Under water level):

Number of cells
Calculated by by SizeX* SizeY

Info :
- - Designs a block type
{ } Designs a loop block

Credits :
deufeufeu / ender (previous research)
VCL (update)

Filed under Uncategorized |

6 Responses to “GAT - Ground Altitude File”

VCL on June 14, 2006 8:44 pm
I believe we have a more correct specification of the GAT file format, at http://www.openkore.com/wiki/index.php/Field_file_format
I’m not sure whether your description of the first 4*4 bytes in the Tiles structure is more accurate than ours, but I’m pretty sure that our description (and the offset) of the type field is more accurate, based on the tests I’ve done.
VCL on October 1, 2006 8:56 pm
And the ‘???’ at offset 17 is 3 bytes, not 4 bytes.
Ximo(Offline) on October 2, 2006 12:49 pm
Thanks, i’ll fix it in a minute
Shinryo on February 22, 2011 12:42 pm
Is the last header information really correct with 3 bytes? Kinda hard to believe. If I’m not wrong, the tile type should be at least unsigned short, resulting the last value also beeing a short value. But as far as this weird format goes, I would even say that the tile type is an unsigned long.
nevelis on October 2, 2011 10:21 pm
@Shinryo - the last 3 bytes are probably just padding for alignment.
Fabs on January 14, 2012 9:21 am
Shinryo makes a lot of sense though. In my project I am reading it as an unsigned int. Remember that the format is little-endian, so there is no difference between reading an int and a byte unless the number represented grows larger than 255.