Partial Cell Indicator not saved in DTED file

[bugbuster]

When converting an SRTM cell to DTED format, the "Partial Cell Indicator" is not saved in DSI header. The correct value is indeed computed after elevation nodes reading / writing step. Curiously enough, this particular field is not treated like all other fields in UHL, DSI and ACC headers. Although the structure psDTED->pachDSIRecord is correctly updated, headers are never rewritten onto hard drive (see DTEDCreateCopy() in dteddataset.cpp).

A solution may be :
1) add a new value to DTEDMetaDataCode enumerate in dted_api.h (DTEDMD_PARTIALCELL_DSI)
2) deal with this new value in DTEDGetMetadataLocation() (see dted_api.c)
3) call DTEDSetMetadata() after Partial Cell Indicator computation (see DTEDCreateCopy() in dteddataset.cpp)

Attached :
proposed patchs for dted_api.h and .c, dteddataset.cpp
an SRTM cell with unknown elevation values

[bugbuster]

Patch for dted_api.h

[bugbuster]

patch for dted_api.c

[bugbuster]

patch for dteddataset.cpp

[bugbuster]

SRTM file to illustrate defect

[rouault]

Fixed in trunk (r24517) (with a little improvement to avoid rewritting the headers to the file each time), and in branches/1.9 with your raw patch (r24518).

Thanks.