# BT – VTP .bt Binary Terrain Format

Driver short name

BT

Driver built-in by default

This driver is built-in by default

The .bt format is used for elevation data in the VTP software. The driver includes support for reading and writing .bt 1.3 format including support for Int16, Int32 and Float32 pixel data types.

The driver does not support reading or writing gzipped (.bt.gz) .bt files even though this is supported by the VTP software. Please unpack the files before using with GDAL using the “gzip -d file.bt.gz”.

Projections in external .prj files are read and written, and support for most internally defined coordinate systems is also available.

Read/write imagery access with the GDAL .bt driver is terribly slow due to a very inefficient access strategy to this column oriented data. This could be corrected, but it would be a fair effort.

NOTE: Implemented as `gdal/frmts/raw/btdataset.cpp`.

See Also: The BT file format is defined on the VTP web site.

## Driver capabilities

Supports CreateCopy()

This driver supports the `GDALDriver::CreateCopy()` operation

Supports Create()

This driver supports the `GDALDriver::Create()` operation

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)