Category: Uncategorized

GPSMAP 66sr and 67 accuracy compared

To prepare for hiking in the mountainous area of Madeira, I bought a Garmin GPSMAP 67. Same GPS chip as my Fenix 7 and Edge 1040, but a better antenna. Due to the observation of some unexpected odd behavior with respect to the Fenix 7 and Edge 1040 and a disturbing error in the device, I do not trust it. Unless Garmin solves this error I am reluctant to use it. Therefore, I also bought its predecessor the Garmin GPSMAP 66sr as well, second hand. Both devices look the same, but differences exist. On some fora I found indication that this device should be more accurate. So lets put it to the test!

Serving your own PDOK maps

I am fascinated by navigation and maps. When I visit a new location one of the first things I do is getting a topographical map of the region. Sometimes I use historical maps, like the Werbata map (dating from 1911, see also Wikipedia) for my trips to Curacao. Since 2007 I log my activities (like running, hiking, cycling, swimming, surveying) using GPS (TomTom watch) and I like to plot these on a map online. Since surroundings change, I like not only to have the most current maps, but also historical maps. As a Dutchy a found the Kabouterbond maps worthwhile. Since 2012 the PDOK Basisregistratie Topografie (BRT) maps which can be downloaded for free in raster or vector format. PDOK is a cooperation between het Kadaster and the Dutch government.

So I end up with a collection of digital maps which I like to use with OziExplorer (for route planning e.g.) and online on my own websites. This post describes the way I proceeded to serve my maps for online usage.

PDOK based vector map from my server, described in this post

White balance underwater

A well known phenomenon to divers is the fact that water absorbs light, the red component in the light the most. This makes water appear blue or greenish. The deeper we get, the stronger the effect: it gets darker and it gets more blue. Diver eyes cope with it, cameras do not, as can be seen from the left picture. Therefore we need correcting the whitebalance, so we end up with something presentable.