[OSSIM] Generic elevation reader.

[Dave B. <Bur...@ge...>]

All,

We now have a generic elevation reader that can use any image file that we can open.  I've updated the ossim/etc/templates/ossim_preferences_template with an example.  Initial test with srtm data is the generic ossimImageElevationDatabase reader is slightly faster than the explict ossimSrtmElevationDatabase.  I've not tested on other file formats yet.

// With ossimImageElevationDatabase:
$ ossim-dem --op ortho test.ntf outputs/t2.tif100%
elapsed time in seconds: 28.066

// With ossimSrtmElevationDatabase:
$ ossim-dem --op ortho test.ntf outputs/t3.tif
elapsed time in seconds: 28.901

Here's a preferences example.  So now you could have tiff's in directory.

elevation_manager.elevation_source1.connection_string: $(OSSIM_DATA)/elevation/srtm/3arc
elevation_manager.elevation_source1.type: image_directory
elevation_manager.elevation_source1.min_open_cells: 25
elevation_manager.elevation_source1.max_open_cells: 50
elevation_manager.elevation_source1.memory_map_cells: false
elevation_manager.elevation_source1.geoid.type: geoid1996

Take care,
Dave