NTV2 FILES FOR COORDINATE TRANSFORMATION WHEN IMPORTING AUTOCAD FILES
Due to a European directive for the standardization of geoinformation, data from the state surveying offices are no longer supplied in Gauss-Krueger coordinates, but in UTM coordinates. Starting with Allplan 2020, it is possible to transform DWG and DXF files with UTM coordinates back to Gauß-Krüger coordinates when importing to Allplan.
The NTv2 transformation method used is based on so-called grid files as support points for the transformation of the coordinates. These are provided by the state surveying offices and are subject to different license conditions depending on the country.
Here you will find the freely available NTv2 files for download. If files are not available, the download package only contains the corresponding folder structures and information on the source of the files. If these countries and regions are selected in the transformation settings, the corresponding information is displayed.
After downloading, unzip the ZIP file and copy the folder structure into the STD\NTv2 directory of your Allplan installation. This makes the transformations available in the office standard.
Please note: If you want to use both packages (Germany_complete.zip and Bavaria_in_one_NTv2.zip), you do no need a separate folder for Bavaria. Copy both structures to STD\NTv2. The DE\09_BY folder then contains all data for Bavaria. The 09_BY.dir file is identical in the two packages.
The folder structure is structured hierarchically by country and region. If you want to use your own NTv2 files, you can insert them into the folder structure. You must also create a *.gsi file in which the EPSG codes and ellipsoids valid for this NTv2 file are entered. A region delivered in the download packages can serve as a template for this.
Further information on NTv2 transformations can also be found at www.crstools.de (German language only)
Be sure to observe the transformation direction. NTv2 files are available for one direction (mostly from Gauß-Krüger to UTM). When importing, you can reverse the direction of the transformation with an option.
You must define the systems yourself. When you receive geodata, always ask in which system the data was saved. You must also define the target system yourself. It is best to use the system in which the data was delivered before the changeover to UTM. This makes the newly imported data compatible with older data.