[gdal-dev] [OSGeo-Standards] Idea: GeoTIFF box in JPEG to addgeoreferencing

Rahkonen Jukka (Tike) jukka.rahkonen at mmmtike.fi
Wed May 21 06:55:59 PDT 2014


Even Rouault wrote:

> A fundamental question that has not been much discussed in this thread is : do
> people really see interest in capturing georeferencing in popular image formats
> like PNG or JPG ? My thinking is that it could be potentially usefull in a few
> situations :
> * when a WMS server returns a PNG or JPG.
> * when generating tile caches for WMTS / TMS.

If an image is a map or aerial image it is worth more with georeferencing than without or of equal value for some users but not less for anybody. WMS is a good example (we have GeoTIFF outputformat as on option just because of that) but there are lots of static map services in the web which deliver just images of maps but which could with a minimal effort attach georeferencing into the maps so that they could be flipped into a GPS device to act as moving map background also for offline usage.

I think that use cases for PNG and JPG are mostly very simple. However, world file is not enough but also the projection code should be advertised. And support for georeferencing by using ground control points would suit very well for scanned maps and digital photos of maps. Inserting a minimal tiff file inside an image in another format may be a dirty trick but at least it works pretty well with JPEG2000.

-Jukka Rahkonen-



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