How to display a geotiff-image with OpenLayers at the “right place”?

Question

I'm just starting with OpenLayers. I have a georeferenced geotiff and the associated world file. Now I want to display this image as an Overlay and google-maps as baselayer with OpenLayers. Would be nice if anybody has some hints? How to get started in the right way? thanks, southente

Answer 1

Openlayers supports projections.

You should know the current projection of your geotiff and specify it to the layer, as EPSG code.

If you have no idea of your geotiff file projection, use gdal to know it.

In command line :

gdalinfo ./path/to/your/geo.tif 

You will get back the desired information

If you don't know the EPSG code, you can get it using http://spatialreference.org/

Some examples are on openlayers' website :

• http://trac.osgeo.org/openlayers/browser/sandbox/camptocamp/canvas/openlayers/examples/raster-reprojection.html
• http://openlayers.org/dev/examples/projected-map.html (this one is broken)
• http://openlayers.org/dev/examples/

Also, reading that page would give you some basics on how projections are handled.