Baaahh......
I redo it .....not exactly equal .....damned google toolbar !.......
I'm ready to dip a toe in, but it's another learning curve ...
If it’s only to change the altitude ,you will see it’s very easy
The only problem is when some coasts extend outward at 0 elevation
It’s just an idea an hypothèse of work ……I remember when I did my first meshes ,five years ago, with the srtm_v1 “not corrected” ,with Blackard to erase the specking noise of the sea ,that was many in these first heights pics, It was needed to set the sea level at -3m.,that calmed the water ,flatten the sea and fix all the land 0m areas, that was showed as water previously and recognize now as land.
Could it be possible ,using Geotiff with slarti or autocoast,to do somes watermasks from "faked" mesh ,with the sea to -3m, and place them on normal ,0m sea level, meshes.
I know that could seem not clear but you can read the full rewiew/tuto:
http://www.terrainmap.com/
"SRTM DEM repair Using BLACKART" on the list band on the left
The english language is also better......
from the “Despeckling SRTM Water Areas” chapter :
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Despeckling SRTM Water Areas
One common type of problem that occurs with SRTM radar imagery over water is speckling or noise. Water surfaces generally produce radar backscatter that often results in noisy images. The surface of the DEM may thus be "speckled" with positive and negative deviations from the actual zero sea-level elevation values. (In addition, coastlines may not be well defined.) An example of this problem is shown in the first image to the right. It is a tile taken from the Eurasia data set, file number N00E073, which is somewhere in the Pacific Ocean south of Sri Lanka. There are actually two problems. The first one is that sea level is a little off, averaging about 3m. The second is the noise. Both these problems are relatively easy to fix.
The oceans can be calmed by shifting the entire data set a couple of meters closer to the center of the earth (actually, the reference geoid.) To do this, select Image|Array Operations| Offset Arrays. Enter -3m into the text field in the dialog box and hit 'Submit'. All the elevations will be decremented by this amount.
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Thanks for everyone's help & understanding. I'm sorry if people feel like we're going over old ground, but I'm new to all of this, & I need to understand how we are where we are (now I'm confusing myself

)
No matter !
there are few experiences about the subject we working on ,almost what we do is new and there are many questions for the diverse way to use and the method .
JP