[mkgmap-dev] DEM: performance with bicubic interpolation

Tue Jan 23 11:21:13 GMT 2018

Hi all,

the bicubic interpolation that was introduced with r4072 is quite slow compared to bilinear interpolation.
I have already changed the code to use a faster method in r4076 but 
you should still expect that run time for DEM calculation increases by up to ~100% compared to code r4071, 
actual values depend on hgt resolution  and your dem-dists values.
So, I wonder if I should add an option that allows to switch this - probably better - interpolation off 
or maybe add an option to switch it on so that faster interpolation is used by default.
The differences in the map are rather small and may be smaller than the errros that come with 
the input hgt data.

Gerd