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ISG Converter
Convert ISG data without installing QGIS or writing ogr2ogr commands. reaConverter is an ordinary Windows application with batch mode built in.
How to Convert .isg Files in Bulk
1. Install reaConverter
2. Select ISG Files
3. Start Conversion
Step by step
See It in Action
For quick and effortless ISG file handling on your PC, reaConverter offers powerful conversion tools with batch processing. Best of all, it works entirely offline — ensuring your sensitive data never leaves your computer.
GIS Toolkit
Do more with your GIS data
Need ISG data as something anyone can open? reaConverter renders imagery and elevation grids into standard images and documents without QGIS or ArcGIS, and works through whole folders in one pass.
- Render imagery, elevation grids and scanned charts to TIFF, PNG, JPG or PDF
- Resize, crop and set DPI on the output in the same run
- Bring tiles, scenes and grids from many sources into one consistent format
- Convert incoming survey and field data automatically with Watch Folders
- Script GIS conversions from the command line for pipelines and scheduled jobs
- Keep cadastral, utility and client data on your PC: nothing is uploaded
User reviews
From those who tried it
Average User Rating:Last updated on July 28, 2026
Questions & Answers
ISG files: Frequently Asked Questions
What are ISG files?
ISG is a plain-text format that stores a geoid or quasi-geoid model as the height of the geoid above a reference ellipsoid. A file has three sections. An optional comment section comes first and typically names the author and the licence, and then a header begins with the line begin_of_head and ends with end_of_head. The header gives the model name and year, the type of the model, which may be gravimetric, geometric, or hybrid, whether the surface is a geoid or a quasi-geoid, the units, the reference ellipsoid, the tide system, and the way the data are ordered, for example from north to south and from west to east. For a grid, it also gives the minimum and maximum latitude and longitude, the step in each direction, the numbers of rows and columns, and the value that marks empty cells, often -9999. The third section holds the heights themselves. Every file also states the version of the format, now 2.0. Because the numbers are plain text, they can be checked in any text editor. To convert an ISG file to graphics, a program reads the header, arranges the values into the grid, makes empty cells transparent, and paints the geoid heights with a color scale. The picture can be saved as PNG, JPEG, TIFF, or GeoTIFF with coordinates.
Can reaConverter open ISG files?
reaConverter fully supports the ISG file format – open, edit, and export ISG files to any other popular file format with ease.
Do I need QGIS or ArcGIS to convert ISG files?
No. reaConverter reads ISG files on its own, so the conversion needs no GIS installation and no licence. It handles whole folders at once, which suits survey archives, tile sets and data deliveries that have to reach people working in other software.
How do I change ISG to another format?
reaConverter is a user-friendly tool for converting ISG files. Once installed on your computer, it allows you to convert all your .isg files at once with just a few clicks. You can even convert isg images directly from Windows Explorer using the right-click menu — fast and convenient.
Why choose offline conversion with reaConverter?
Keep your sensitive data 100% private with offline processing that never exposes files to cloud risks. Our software meets strict compliance standards (GDPR, HIPAA, CCPA) while handling confidential documents for legal, healthcare and financial sectors.
Can I convert ISG online?
If you only want to convert a few ISG files, you are welcome to try our free online ISG converter.
How can I turn ISG files on my computer to another format?
The best way to convert ISG files on your PC is to get a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch files conversions, including conversion from ISG.
How can I automate ISG files conversion?
reaConverter supports all the essential automation features, such as right-click сonversion and Watch Folders, for the most efficient automated file conversion in any software of its kind.
Can I convert ISG files using scripts or the command-line interface?
reaConverter provides full access to all its features from the Windows command-line shell, including the command-line isg converter.
What else can I do with reaConverter?
Convert GIS filesConvert DICOM filesCrop photoChange format settingsCopy metadata (EXIF, IPTC)
What formats can I convert a ISG file to?
Discover More
Beyond ISG conversion
Convert .isg files in batches of any size, with editing and processing applied along the way. The same tool also handles 800+ other formats, including CAD, medical imaging, and GIS.
