StefanDarecki

Thank you all for your comments. Based on them I think I will do the following: 1. I will get GPS unit with barometric altimeter. It looks like the GPS is not as accurate when it comes to altitude as it is for x/y coordinates. I hope go get better *relative* results with the barometric altimeter. 2. I won't carry the unit in a backpack. In order to not to obstruct the view of satellites, maybe I will fix it discreetly on my neck, or maybe under a baseball cap (I hope it won't look suspicious or ridiculous ). Of course I will subtract my height from the recorded data. But since I'm more about relative altitudes (relative to some starting point with well-known altitude), this shouldn't be a big problem. 3. I will carefully read instructions for calibrating the altimeter, and do as many tests before actual measurements as needed. One of the tests I was thinking about was to start walking from point A, go uphill to point B and return down to point A. In theory when returning to point A I should have the same altitude recorded as at the beginning. If the path is short enough I should avoid (or minimize) the negative impact of changes of atmospheric pressure. 4. I will also try to make the measurements on days when weather forecast predicts stable atmospheric pressure. Avoiding the measurements in the morning and evening seems to be a good idea. Thanks again to all commenting people. I will continue to watch the discussion about calibration of barometric altimeter.

Hello, I know that this question is not related directly to geocaching, but I thought that I may try ask it here. Here is what I want to achieve (short version): to create a map (x/y coordinates + height) of specific area Here is what I want to achieve (long version): There is a rural area, 5x5 km large. Not many trees, some low buildings, tourist paths and some dirt roads. Altitudes ranging from ~200 to ~250 m. GPS coverage seems to be good, I can easily get 5-6 satellites on my mobile phone. Central Europe. I would like to create a map of the tourist paths and roads, with exact x/y coordinates, as well as altitudes along the paths. I don't want to create a grid of x/y/z values, it would look more as an irregular mesh or spider web. I don't want to have coordinates of every point in that area, just paths and roads. I want to collect the data by just carrying the GPS device in my backpack, and walking with it in the terrain. Technical side of extracting the data from the device and then processing it further is out of scope of this post, I think that I can solve it myself. I know that I could adapt data from existing sources, but I want to do this entirely on my own, just for fun. I've been thinking about using devices such as Garmin Dakota, or Garmin eTrex - this type of devices, more or less in this price range. I don't need to have a military-grade resolution, but the more I can get from this kind of devices, the better. Now here is the question #1: in order to achieve this goal should I get a device equipped with barometric altimeter? Will I gain much from having it in my device? Does it increase precision of measurements of altitude (or, to put it another way, does it provide better *relative* accuracy than pure GPS)? By "relative" I mean "I know that this point here has altitude 220m, I want to know the height of that point over there". Question #2: how slow should I walk to ensure correct acquisition of data by such devices (devices in this class)? Could you please share your thoughts on this topic? I will be grateful for any input and advice. Edit: "as well as latitudes along the paths" -> "as well as altitudes along the paths"