Hi Ticker, Funny, I would have used Integer.MinValue for maxDx/maxDy to make it less confusing. Do you have an explanation for the change in size? My understanding is that your patch just skips a test which will never find a better encoding? Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Donnerstag, 8. April 2021 13:58 An: mkgmap development Betreff: [mkgmap-dev] Polyline base optimisation Hi Gerd If starting with unsigned deltas in polyline encoding, and attempting to reduce the length by testing reduced x/yBase values, there isn't any point in testing Base-1, as the normal number of bits will be the same (added sign bit) and there will be some overflows. Patch attached to change this - it gives me a very slight reduction in RGN size and might give a performance improvement (I didn't detect any). I've also fixed a couple of log. logic errors and changed minDx/y initial to 0, which is much less confusing because they are symmetric with maxDx/y which do use 0. Ticker