Great discovery Gerd!
Enviado do meu iPhone > Em 16 de jul de 2016, às 14:28, Gerd Petermann > <[email protected]> escreveu: > > Hi all, > > > during the last days I tried to find more about the way how mkgmap stores > polygons, esp. why we have some limits. While doing that I stumbled over an > > old comment in LinePreparer.java: > > // I don't care about getting the smallest possible file size so > // err on the side of caution. > which made me curious because I do care ;-) > > > I found out that Garmin offers a "trick" in the delta encoding which allows > to reduce the needed bytes in some cases, the imgformat-1.0.pdf > > explains this in detail, search for " only the sign bit is set ". > > This "trick" helps esp. well when coastline polygons or rivers are stored. > > > I can explain this more detailed if somebody likes to know more, > > for now I'd like to hear if the trick causes any problems, I did not find any > > so far. > A binary with this and a slightly improved overview_levels_v2.patch > can be found here: > > http://files.mkgmap.org.uk/download/301/mkgmap.jar > > > Depending on the data a single tile with size ~5MB may be reduced by 50 - > 500+kB. > > Gerd > <reduceImgSize_v1.patch> > _______________________________________________ > mkgmap-dev mailing list > [email protected] > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
_______________________________________________ mkgmap-dev mailing list [email protected] http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
