Conversion Formats
Below, you will find for each supported format more info
ASCII
The ASCII file format is a versatile file format that accommodates a broad range of file structures.
Coordinates may be represented in either latitude and longitude or in easting and northing.
Each row must include a coordinate and a height.
For detailed information about the dialog, see the ASCII file configuration dialog.
All coordinates must maintain a consistent spacing; otherwise, a message will indicate that conversion is not possible.
ARC ASCII
The ARC ASCII file format is an Esri grid, a raster GIS file format developed by Esri. This format is also referred to as the Arc/Info ASCII grid.
It features a header structure that specifies the grid's reference, followed by the values presented in the order they appear (left to right and top to bottom).
ncols 4
nrows 6
xllcorner 0.0
yllcorner 0.0
cellsize 50.0
nodata_value -9999
-9999 -9999 5 2
-9999 20 100 36
3 8 35 10
32 42 50 6
88 75 27 9
13 5 1 -9999Where:
ncols is the number of columns (represented as integers)
nrows is the number of rows (represented as integers)
The lower-left corner refers to a cell corner, not to a data point
xllcorner and yllcorner are the western (left) X coordinate and southern (bottom) Y coordinates (represented as real numbers with an optional decimal point). An alternative is the use of xllcenter and yllcenter.
cellsize is the length of one side of a square cell in degrees. Alternatively, it could contain xdim and ydim.
xdim is the length along the horizontal side of a cell in degrees.
ydim is the length along the vertical side of a cell in degrees.
nodata_value is the value that is regarded as "missing" or "not applicable."
The remainder of the file lists the raster Z values for each cell, starting at the upper-left corner cell. The Z values are always reported for the center of each grid cell. These real numbers (with an optional decimal point, if needed) are delimited using a single space character.
Based on the header values, if the resulting minimum and maximum X and Y coordinates remain within the latitude and longitude boundaries, the file is considered geographical; otherwise, it will be regarded as projected.
ISG
The International Service for the Geoid has developed a format for providing models. This design adheres to format version 2.0 and extracts all necessary information from the file header. Below is an example for detailed information: https://www.isgeoid.polimi.it/Geoid/format_specs.html
begin_of_head ================================================
model name : EXAMPLE
model year : 2020
model type : gravimetric
data type : geoid
data units : meters
data format : grid
data ordering : N-to-S, W-to-E
ref ellipsoid : GRS80
ref frame : ITRF2014
height datum : ---
tide system : mean-tide
coord type : geodetic
coord units : dms
map projection : ---
EPSG code : 7912
lat min = 39°50'00"
lat max = 41°10'00"
lon min = 119°50'00"
lon max = 121°50'00"
delta lat = 0°20'00"
delta lon = 0°20'00"
nrows = 4
ncols = 6
nodata = -9999.0000
creation date = 31/05/2020
ISG format = 2.0
end_of_head ==================================================
30.1234 31.2222 32.3456 33.4444 34.5678 36.6666
41.1111 42.2345 43.3333 44.4567 45.5555 46.6789
51.4321 52.9753 53.6543 54.8642 -9999.0000 -9999.0000
61.9999 62.8888 63.7777 64.6666 -9999.0000 -9999.0000Trimble GGF
The GGF format is specific to Trimble software and is proprietary. Due to the complexity of height storage in the file and the lack of diverse example files, a warning message will appear if the loaded file contains an untested flag. In such cases, we recommend additional manual validation of the converted model.