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Thread: Does any GPS do this?

  1. #1

    Does any GPS do this?

    I work for a small company and want to use a handheld GPS to plot points as I walk around a site then, having stored the information, go back to the office and download the shapes/polygons onto a 1:10,000 OS Vectormap. This would produce an accurate representation of the features on the site I am trying to map.

    The points are likely to be fairly far apart (as you can tell from the fact I'm using 1;10,000 mapping) so I don't think the GPS should be confused by a series of points that could almost be 'in the same place'.

    As said small company - limited resources - so the GPS and any software package to translate the info onto the OS tiles needs to be at the cheaper end.

    So:

    1. Is this possible?

    2. What GPS and system to make it work?

    3. What cost?

    4. What shop to visit if it is possible? - I'd prefer to deal with a person not instructions and online advice (rueful smile!) - somewhere between Leeds and Newcastle.

    Finally I have already contacted the OS - they were no help beyond suggesting I talk to the retailers/manufacturers of GPS systems.
    Thanks - long first post!

  2. #2
    Super Moderator captain paranoia's Avatar
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    Essentially, all you seem to be after is a collection of points that you can import into a GIS to mark polygons.

    If you have a smart phone and a GPS mapping app, most of them will come with POI (point of interest) or waypoint entry dialogues. You'd just drop a POI at your current position, and then export the set of POIs to your GIS and convert them into shapes/polygons.

    Essentially free if you already have a GNSS-equipped smartphone. There are loads of free GPS-related apps; get playing.

  3. #3
    Quote Originally Posted by captain paranoia View Post
    Essentially, all you seem to be after is a collection of points that you can import into a GIS to mark polygons.

    If you have a smart phone and a GPS mapping app, most of them will come with POI (point of interest) or waypoint entry dialogues. You'd just drop a POI at your current position, and then export the set of POIs to your GIS and convert them into shapes/polygons.

    Essentially free if you already have a GNSS-equipped smartphone. There are loads of free GPS-related apps; get playing.
    Thanks for the response - I understand though that such apps do not necessarily work when there is no mobile signal. And there is no mobile signal - most of the places I work have no or patchy mobile signals. Given that is a dedicated GPS unit preferable?

  4. #4
    Initiate padstowe's Avatar
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    To the best of my knowledge (which aint much) gps apps on phones work through the gps signal not the phone radio signal. You can of course set your phone to work off both but its not necessary to do so.

  5. #5
    Super Moderator captain paranoia's Avatar
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    > I understand though that such apps do not necessarily work when there is no mobile signal. And there is no mobile signal - most of the places I work have no or patchy mobile signals. Given that is a dedicated GPS unit preferable?

    I think your understanding is incorrect, or outdated.

    GNSS is not reliant on the mobile phone reception (unless you're using the mobile data to get A-GPS ephemeris data to speed up a cold start; even then, all you have to do is wait a bit for the GNSS receiver to acquire the ephemeris and almanac from the satellite constellation broadcasts, which most modern phone GNSS receivers will do very quickly).

    The only reception problem is if you cannot see the sky (and hence the satellite constellations), and that will apply to a phone GNSS receiver or a dedicated GNSS receiver.

    Some phones will use a fused location service, relying on GNSS signals, mobile mast and WiFi triangulation/power analysis, to fuse a single position to deal with the loss of sky view in an urban environment (the 'urban canyon').

    [edit]

    To give you an example, I've just opened the 'GPS Status' app on my cheap Moto-E, which turned on the GNSS location service. It immediately downloaded the A-GPS information via WiFi. I then turned on aeroplane mode, thus disabling the GSM and WiFi systems, and put it near a window in the house, and within a few seconds, it had acquired a fix.

    I have a fair bit of experience with GNSS over my professional career as an electronic design engineer, including working on the 'golden reference' constellation simulator for ESA's Galileo system (GSVF-2), so I'm commenting from a position of some knowledge...
    Last edited by captain paranoia; 20-10-2016 at 08:11 PM.

  6. #6
    Ultra King Martin Carpenter's Avatar
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    I've certainly used a phone with viewranger/mobile data turned off to track sundry walks by now

  7. #7
    Mini Goon andrew_s's Avatar
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    Bear in mind that the GNSS will produce data in a different coordinate system (WGS84) than is used by OS Vectormap (OSGB36), and if you don't get the transformation right, your positions will be wrong. There are various online converters (eg http://www.gridreferencefinder.com/b...tchConvert.php )

    You will want to take positions at a number of control locations that you can identify on the map so you can make sure you are getting the transformation right. These locations should NOT be close to the road, as Vectormap uses standardised road widths (about 16 m), with the marked road edge not being shown in its true position. This may mean that features next to the road get moved over to make room. Similarly, the shapes of most buildings will get simplified, so that houses are almost all simple rectangles regardless of protruding kitchens, garages etc.
    Wall junctions and corners can make good reference points.

  8. #8
    Super Moderator captain paranoia's Avatar
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    > Bear in mind that the GNSS will produce data in a different coordinate system (WGS84) than is used by OS Vectormap (OSGB36)

    Doesn't OS Vectormap import WGS84 coordinates into its local coordinate system? That would be a very basic function of a modern GIS tool.

    Ah, OS Vectormaps says:

    "OS VectorMap products are designed as a backdrop map for GIS".

    So your GIS should be doing the coordinate transformation. If it can't import WGS84 and overlay onto OSGB36 mapping, look for a better GIS... Or convert the GPX file to a compatible format using something like GPS Babel.

  9. #9

    Does any GPS do

    Hi,I work for a data recovery lab and was experimenting with A Seagate ST3100528AS model with firmware CC44. Initially I could access some sectors at the end of the drive, but not at front. I ran a Format User Area after backing up the resources to see what it does. Now I cant access any sectors. Any way we can recover it with saved resources? I tried translator regeneration, which doesnt work.

  10. #10
    Widdler
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    Does any GPS do this

    How does this guy play at the highest level of competition. And put tones of effort into defense without any expression lol.

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