[A]this is a commit tests  /QQ截图20140328152709.png
[M]modify the process of mask layer for solving multiple masks per tile
Removed some unused variables
Merge branch 'master' of https://github.com/gwaldron/osgearth
Add mimetype alias for dds
Merge branch 'master' of github.com:gwaldron/osgearth
Fix for infinitely subdividing terrain

Fix in ElevationLayer to return whether or not we actually got any real
data in populateHeightField.  Previously it would return true even if no
heightfields were sampled causing infinite subdivision if a layer didn't
provide proper data extents.
Merge branch 'master' of https://github.com/gwaldron/osgearth
Re-enabled old GDAL createHeightField path until we can fix issues with accuracy and gaps with the new method.
Merge pull request #480 from chenxiaoyu358/master

Merged
Fix g++ build error