Hi Alex:
Sorry for the delay in replying here... I've been rather busy as well.
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Indeed, using a more accurate DEM may help make it much easier to control the development process of you are trying to achieve.
However, one must still ensure proper size / shape, as well as horizontal ("X-Y" or Lon-Lat) and vertical ("Z" or elevation) alignment of all one's terrain scenery component layers including vector, raster, and mesh content.
Making
copies of a master terrain scenery object (such as the island's custom vector shoreline polygon) used as a "template" for creating, positioning, or comparing with other scenery layer objects and masks, may help maintain alignment for a project.
NOTE: If you find that the cost of commercial DEM elevation data at higher resolutions is too prohibitive for your island projects, I'd suggest that making an over-sampled mesh from ASTER GDEM2 data would provide the mesh data and terrain quad matrix grid vertex resolution required for a detailed shoreline to be displayed at the level of detail you apparently want.
As you can see from the table I posted in this thread:
http://www.fsdeveloper.com/forum/showpost.php?p=633002&postcount=31
...the FSX SDK Resample LOD output resolution of the BGL (when lower-resolution DEM source data is purposely over-sampled) will depend on how close together you need / want your terrain vector vertices.
If, for example, you wanted to use the minimum default inter-point distance interval in SBuilderX at 20 Meters (62.99194 Feet) between FS terrain vertices defining a poly-line or polygon, you would require a terrain mesh BGL with at least a LOD-11 output resolution (to allow 19.2 Meters between Area Points in the FS quad matrix grid "
if" the terrain mesh resolution slider of FSX is
also set at 20 Meters or less with the FSX mesh complexity slider set at 100 %).
And if instead you wanted to use an even smaller inter-point distance interval in SBuilderX of
ex: 10 Meters (31.34731 Feet) between FS terrain vertices defining a poly-line / polygon, you would require a terrain mesh BGL with at least a LOD-12 output resolution (to allow 9.6 Meters between Area Points in the FS quad matrix grid "
if" the terrain mesh resolution slider of FSX is
also set at 10 Meters or less with the FSX mesh complexity slider set at 100 %).
IIUC, one would also need to pre-configure SBuilderX to allow use of a smaller inter-point sample distance interval of
ex: 10 Meters (31.34731 Feet) between FS terrain vertices when defining a poly-line / polygon ...by editing this
SBuilder.ini file parameter to read:
[Main]
SampleDistance= 10
However, the terrain mesh elevations resulting from over-sampled ASTER GDEM2 data may have anomalies (such as was the original basis for this thread); IMHO, correcting / minimizing those anomalies might best be done via CVX vector 'sloped flatten' polygons.
BTW: If you wish to preserve the details of the rocks extending out into the water at the base of the cliffs along the coast of your island(s), you must re-work the default and/or other underlying water hydro polys to allow the terrain mesh to "
pop up through the water" and enable display of the raised terrain mesh elevations (rather than being displayed as textures draped over the
flat water surface); AFAIK, this is all to be achieved via vector / raster exclusion / replacement / masking processes which require precision shaping and alignment using
ex: SBuilderX.
And, as Rhumbaflappy points out, the ASTER GDEM2 still has not been revised as extensively as other DEM sources to minimize various anomalies, and some world areas may require more work to clean it up than in other areas.
I would
not try to use sloped flattens
along the shoreline at the level of the water, as that should IMHO, be fixed via terrain scenery component layers of vector and raster excludes / polygons / textures / masks.
Instead, you may wish to make
smaller local sloped flattens to attenuate the extent and shape of the anomalous vertical elevation "peaks" discussed above.
And rather than including the shorelines themselves
within the sloped flattens, you may wish to try simply having the edges of the sloped flattens "
meet" the vertices of the underlying terrain mesh at the "in-land" edges of the shorelines ...
before they drop down to sea level.
PS: I would again encourage you to consider testing the ideas regarding
pre-alignment of one's terrain vector vertices (for
ex: sloped / tilted flattens) onto the known vertex positions of the FS quad matrix grid, to minimize possible additional run time terrain engine rendering anomalies which may
complicate the excessive "vertical exaggeration" incurred when oversampling DEM data in FSX SDK Resample ...as discussed in this thread:
http://www.fsdeveloper.com/forum/showthread.php?p=632968#post632968
FYI: If the geographic coordinates of one's custom vector vertices '
fall in-between' the terrain vertices of the FS quad matrix grid, at run time during a flight, the FS terrain rendering engine may create pits, spikes, or otherwise exaggerated negative
or positive elevations either close to (or wildly out of keeping with)- the elevation "requested" at our own specified terrain vector vertex positions ...resulting in terrain anomalies via a mechanism independent of those induced by Resample due to over sampling of terrain mesh source data.
Thus, we may sometimes need to use a FS SDK Resample higher LOD resolution output for a terrain mesh BGL (even if source data resolution is lower than the intended output LOD) to create a greater density of terrain vertex positions which are closer together, in order for our custom terrain vector points to be able to align with the FS quad matrix grid Area Point positions, thereby allowing us to render and display the desired shape for our terrain at run time during a flight ...with less risk for anomalies.
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Hope this helps !
GaryGB
