RFC 24: GDAL Progressive Data Support

Author: Norman Barker
Contact: nbarker@…
Status: Development

Summary

To provide an interface for data streaming support to GDAL by overloading the RasterIO function to include a callback function when there are buffer updates. The RFC focuses on JPIP but should be generic to apply to other streaming / progressive formats.

Definitions

JPIP: JPEG 2000 Interactive Protocol

Objective

To provide a callback function to allow users of a progressive format driver to receive notifications of updates to the underlying dataset for a particular requested region of the data. The notification mechanism should be accessible to all the swig wrappers and the underlying buffer data should be conveniently stored to allow conversion to a raster format - e.g. png, windows bitmap.

Implementation

The implementation is a definition of an interface, currently the most convenient streaming library is ​Kakadu however since GDAL is a developer library only stubs can be distributed to conform to Kakadu licensing ​FWTools Licensing. Commercial vendors are also interested in using GDAL for streaming support and a standard interface will allow these commercial plugins to be incorporated.