GeoDLL - Geodetic Development Kit
Function group "NTv2 Tools"

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NTv2 Tools

The group "NTv2 Tools" contains functions that allows the manipulation and data retrieval from NTv2 ASCII grid files and NTv2 binary files.
NTv2 files are either in ASCII format or in binary format. With the functions convntvascii2bin() and convntvbin2ascii() can be converted between the two file formats.
There are some very large NTv2 binary files that are larger than the 2.15 gigabytes addressable with the "long int" C variable type. For example, the Bavarian NTv2 binary file BY_KanU_Bayern-gesamt.gsb has a size of about 3.5 gigabytes. Unlike the Software GeoDLL and TRANSDATpro by KilletSoft, many geodetic programs and GIS can not handle such large NTv2 files. With the function convntvbin2area() it is possible to copy an area defined by a coordinate section from a NTv2 binary file into a new binary file. All grid data of grids of the binary file, which intersects the coordinate section, are taken into account. The new binary file created in this way is smaller and can be used with any geodetic software and GIS.
An NTv2 file contains one or more quasi-rectangular coordinate grids which are defined in the NTv2 headers. Instead of a rectangular area only an embedded polygonal area should and must be covered, for example, a state territory within the country borders. The function convntvbin2polyvalid() realizes the Polygonal Validity Scope in NTv2 files. For that purpose the polygonal scope is realized with a shape file that contains the outlines of the scope as polygons. Coordinates outside the scope then can be excluded from calculations or be acknowledged by a warning using the KilletSoft products TRANSDATpro and GeoDLL and a lot of GIS software developed by companies which supports Polygonal Validity Scopes.
With the export and import functions convntvbin2gridexport() and convntvbin2gridimport() NTv2 grids can be arranged arbitrarily in binary NTv2 files.
Further functions of this group determine the header data of the of NTv2 grid files or their grids, which can be used to analyze ord manipulate NTv2 files.

Download of the NTv2 grid files in binary format

The NTv2 grid files supported by the program TRANSDATpro and the function librariy GeoDLL you can download  here from the KilletSoft website!

Characteristics of the group "NTv2 Tools"

1. ASCII grid files (.gsa) and binary grid files (.gsb)
2. Conversion of ASCII grid files to binary grid files
3. Conversion of binary grid files to ASCII grid files
4. Copy of NTv2 grid file areas to new binary files
5. Supplement of a NTv2 binary file with Polygonal Validity Scopes
6. Determining the parameters of a NTv2 grid file
7. Export and import of NTv2 grids
8. Download of many NTv2 files from the KilletSoft website
9. Links to NTv2 providers on the KilletSoft website
10. HARN grid files of the U.S. supported as equivalent NTv2 grid files
11. Free use of some NTv2 files, which otherwise are available for a fee
12. Access to NTv2 files, which are specially licensed for KilletSoft

Functions of the group "NTv2 Tools"

1. Function convntvascii2bin() - Converts a NTv2 ASCII file to a binary file
2. Function convntvbin2ascii() - Converts a NTv2 binary file to an ASCII file
3. Function convntvbin2area() - Copies an area of a NTv2 grid file to a new binary file
4. Function convntvbin2gridexport() - Exports a NTv2 grid from a NTv2 binary to a new binary file
5. Function convntvbin2gridimport() - Imports a NTv2 grid from a NTv2 binary into an existing binary file
6. Function convntvbin2polyvalid() - Adds Polygonal Validity Scopes to NTv2 binary files
7. Function getntvgridarray() - Writes parameters of NTv2 grids to arrays
8. Function getntvgridcount() - Gets count of grids contained in a NTv2 file
9. Function getntvgridheader() - Gets the header parameter of the NTv2 grids
10. Function getntvheader() - Gets the header parameter of a NTv2 file
11. Function getntvminmaxshift() - Gets the min / max shift values of the NTv2 grids

Ausführliche Funktionsbeschreibungen

Detailed descriptions of all geodetic functions of this function group you find here in the online manual!