Generate GGF files Geoid grid file with Grid factory

GGF files (Geoid Grid file) is a geoid model file for use in Trimble series software and receiver controllers such as TGO, TBC.

Trimble Official website provides download of common geoid Grid file.

Trimble also offers a free conversion management tool grid Factory for generating, viewing, and analyzing GGF files.

GGF files and Grid factory can be downloaded at the following address:

http://www.trimble.com/globalTRLTAB.asp?Nav=Collection-37882

Grid Factory supports ASCII files in a specific format and generates GGF files according to the custom template.

The ASCII file format is:

Descriptor	Dsaa
Numberx Numbery	403 280
MinX MaxX	34.06252 50.81252
Miny Maxy	20.64584 32.27084
MinZ MaxZ	-32.393 21.951
Z1	8.427
Z2	8.399
......	.....

In the above ASCII file, the z value is the geoid gap value (Geoid separation), each value is a row, starting from the Z-value of the lower-left corner of the rectangular range of the GGF, first according to the west-east direction, after the completion of the entire line, according to the north direction from the south to write all z-values. See table:

22	23	24	25	26	27	28
15	16	17	18	19	20	21st
8	9	10	11	12	13	14
1	2	3	4	5	6	7

ASCII file type:

Here's how to generate a GGF file with a text file in grid factory.

1. Select File-open Grids in the grid factory

2. In the Grid Import dialog box, click New, open the grid import Template Wizard, and enter the DESCRIPTION:NW to generate the grid.

3. Set the Grid Datum Basis

4. Set interpolation Method

5. Set the grid File Type

6. Set up Data offsets

7. Set the data Record Length

8. Set Missing Values

9. Set Axis Orientation

10. Set the rows is latitudes

11. Set Columns is longitudes

12. Set the Grid File Data Types

13. Set Geoid separation Data

Click Finish to complete the template settings, return to the Grid Import dialog box, click Import, with the template just set to import ASCII file

In the Latitude/longitude Grid File Names & Descriptions dialog box, fill in the description

Click OK

The geoid model is displayed in the Grid factory, the default display mode is to display the grid grid, the show grid intervals is reversed under the View menu, and the resolution is set at View--color. As shown in the GeoID model.

Generate GGF files Geoid grid file with Grid factory