FT's GOTOPO30 data not accurate? Or is it Peak & Depth parameters?
GOTOPO30 is very high resolution data, but I found some area is not correct. Like the Peloponesean Peninsula, the Corinth Bay is way too narrow..... and Gibraltar is connected to Spain. Is it because of the peak and depth parameter (+30000 and -30000) when loading the data into FT3?
Comments
Because a height value given in a grid point is a mean of all the heights in the surrounding up to 500 meters in all directions (plus that sea values are zero) you will always get a higher value than zero for grid points near the coast.
That means that the (default blue) water areas (h=0 m) are up to 1 km smaller.
This is the effect that you get aware of in FT3 especially in narrow parts of the sea.
So it is not an error in FT3 - this is due to the limitations of the GTOPO30 resolution and that it has no negative values for the depths of the sea.
/André
I put all of the GTOPO30 into QGIS and combine them together, this is the final image.