Hot answers tagged dem
As whuber mentioned, often statistics found in the raster properties are sometimes approximate or are out-of-date. They are predetermined properties that can be misleading to the actual raster values. Calculated your own min / max values from 100% of the actual data using NumPy arrays. See Working with NumPy in ArcGIS, and RasterToNumPyArray (arcpy). E.g.: ...
Note that both methods below will export non smoothed polygons boundaries. You may have to resample your DEM file to get smoother lines or use further smoothing techniques. Step 1: Spatial Analyst (Classification) You could use Spatial Analyst to classify your data in 2 classes: 1 = data within the boundary values (example : elevation < X meter) 0 = ...
As the other replies say the statistics are likely out of date. If you prefer using ArcGIS try the Calculate Statistics tool in the Data Management toolbox. This should update the statistics for you.
Your main question title indicates you're looking at sea level and coastal areas. But we'll start at the bottom of your question and work backward. Consider lakes and rivers. Many of them may be significantly above sea level, even their bottoms, thus relying on elevation alone in the DEM cannot tell you if an area is water or not. Plus in a DEM large water ...
Now, the answer from the developers of the tool, who kindly allowed me to forward the answer here. I translate and do my best to reproduce what I learnt from Dr. Conrad: The only expected input-dataset is the DEM. The tool runs an interative procedure which works with relative relief-position. The same procedure is used to calculate - the vertical distance ...
You can use the function ST_DumpAsPolygons: SELECT (ST_DumpAsPolygons(rast)).* FROM road_linestring_table,dem WHERE ST_Intersects(rast, geom); Afterwards you can rasterize the result.
I imported my raster file to PostGIS and I used this function to make vectorization of my raster. I used this query SELECT (ST_DumpAsPolygons(rast)).geom,(ST_DumpAsPolygons(rast)).val from my_raster
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