SRTM and shores - need pointers

[Guest]

I am totaly n00b here, and I'd be very much grateful for any pointersabout the following problem:How could I remove the sea noise and create a flat sea with alt 0up to the land. Any algorithms for that, specially for data close to land??

[Guest]

... post in the wrong place?... stupid question?... "n00bs get lost" see FAQ/RTFM?:-newbie :-outta :-badteeth :-hang

[Holger 0]

Howdy:yeah, newbies are a pest - just kidding.Actually, it's an interesting question and I mentioned the ocean elevation issue inherent in radar data in the "New SRTM_3ArcSec_To_BGL - Fixes holes in SRTM data" thread (post #13). I don't think that there's a way to remove the water "noise" other than by merging with a different data source that already has correct seashore boundaries. Which, I suppose, kind of defeats your intended purpose.Why do you want to use SRTM for extracting sea shores? There's probably much better freeware vector data available of coastlines worldwide, e.g. at http://data.geocomm.com/readme/dcw/dcw.html If you want to create an accurate shoreline along with the SRTM terrain mesh you'll need vector data anyway to compile a new hydrography .bgl (or so I think)Also, "re-meshing" of coastal areas has been discussed extensively in the Scenery Design forum. Cheers, Holger

[Guest]

Thank you very much Mr. Holger! :-beerchugI'll will read the the suggested material.About your question, why I want to use SRTM for extracting shores.It is not that I'd like to use that for extracting shores, I want the SRTM for land data use, but since the water is so noisy and it seems at times hard to diferentiate between water and land I was wondering which method would be useful to implement to flatten water...now you gave me few ideas, 1. merging different data source, which might also solve the "holes" problem, however I am a bit woried about the resolution of data such as GTOPO30 (the only besides SRTM I have now, and I have to check if gtopo has flat waters). 2. using vector shore data to set the boundaries such as GSHSS (Global Self-consistant Hierarchical High-resolution Shorelines )but its best resolution is 0.2 km (200m, while SRTM 3arc at equator is 90m and less up the poles). Primarily I dont want to create a BGL, just a clean SRTM data file...

[Guest sgreenwood]

>since the water is so noisy and it seems at times hard to >diferentiate between water and land I was wondering which >method would be useful to implement to flatten water...If you just want to generate basic mesh from the SRTM data, this should not be a problem. For better or worse, in the sim, Microsoft "rules the waves". Water levels are fixed and flat and shorelines are fixed. This is one situation where we benefit from an otherwise often annoying feature.Go ahead and make a small area of mesh and test it in the sim.Stevewww.fs-traveler.com

[Justin Toposim 16]

Hello,I use Manifold 5.5 to preprocess my data. It has numerous Transform Operators, two of which are called Threshold Upper and Threshold Lower. I set these to zero and and run the transforms. This accomplishes what you need.http://www.manifold.netGreat application, by the way. Highly recommended.-------Justinhttp://www.fsgenesis.netHigh Quality Scenery for FS200x

[Guest]

Hi,Thank you very much, for your input!Checking it out...

[Guest]

Hi,Thanks! :)BTW, nice page u have, was quite educational for me!