5.0 DEM support issue?

Hi,
I like the 3D fuction in Oruxmpas 5.0. It works well with .hgt file download from NASA website. While, SRTM v2 data (GeoTiff format) is better, which "modifed" some "holes" data in .hgt files. i am in China, it is important.
I knew 5.0 can not support SRTM GeoTiff directly, so i transfered them to .dem, unfortunately, Oruxmaps still says "no 3d data". I copied a .hdr into the dem directory, 3d model can work, but it show a "flat" map.
Note, i used global mapper 14 to export .dem file, which includes necessary map info. it could be opened in GM without .hdr.

ixuhui