[talk-ph] mobile mapping rig / buddy-system mapping tip (warning: long email)

Rally de Leon ralleon at gmail.com
Mon May 18 07:30:50 BST 2009


Ronny,

If I use a car on a long trip (mapping), a small laptop/notebook is
definitely an advantage in mapping because of the wider screen (as long as
you have somebody typing for you). You can see farther and visually plan
your target area. You save gas because you don't go to areas further than
necessary. You ride in tandem, so that one concentrate in driving
as-centered-as-possible to the road (for quality tracks), while
concentrating on safety and minimizing traffic obstruction; while the other
person concentrates in typing directly on laptop with good eyesight for the
correct spelling of the POI, far signboards and street signs. You can do
more with less movements if you do a buddy while mapping.

I use an Eeepc that runs on 12v DC (3A). the older eeepc that runs on 9v is
easier to power since it's fairly resistant to the voltage drops (9-10v)
from the car's cigarette lighter plugs (every now and then). You will notice
your laptop (switching in-and-out of battery power) which is very annoying.
Clean/regulated 12v DC is hard to achieve (from a 12-13.5v power source); so
I am forced to use a less elegant solution: DC-AC converter (bulky aluminum
case).

Neil (my good navigator encoder) suggested that I use a "voltage multiplier"
to push the voltage up to maybe 17-20v DC then force it back down again to
12v using any cheap commercial lighter-plug DC regulator. That way, the
laptop won't notice the voltage drops. Your digital VOM will not tell you
how dirty your car's voltage is. I had to bring an oscilloscope to our
garage to verify this (out of desperation). I will work on this DC regulator
project next week. I need help from any ECE or electronic hobbiest here. :-)

BTW, I'm a windows users, so Nroute works best for me because I can easily
load OSM's latest garmin map as reference in the background; and it can do
1-sec tracklogs. Garmin stopped support for nroute, so you may need to
download it somewhere. Equivalent linux mapping software will also work, and
it may be worth it because of the bigger-screen size advantage of laptop.

For antenna, you can use an ordinary standalone-garmin receiver placed on
your dashboard, connected to your laptop via serial or USB cable. Advantage:
it's easy to use. No need for GPSproxy. the garmin signal is read directly
by Nroute. Disadvantage: older garmin receivers need separate batteries to
power itself, unlike the newer ones that can be powered via USB from your
laptop. I think you may also use a magellan receivers paired with gpsproxy.

But for my case, I just bought the cheaper generic gps USB roof antenna
(amazon @ $30+ sent via balikbayan box) that can be placed at the left edge
of the car (nearest the center of the road). The advantage of a roof mounted
antenna can be realized when entering urban canyons (streets with high
buildings on both sides). Sometimes, one of the few available/critical
satellites are positioned 45-degrees at the back of your car. A dash-mounted
antenna cannot see this satellites.

Downside of this is when you go out of your car every few stopovers. If you
shutdown your laptop, you have an additional program (gpsproxy) to turn-on
before you run nroute again. (it will take a minute or so before you can
drive again) unless your navigator can do it for you always. Solution: buy
the original garmin external usb antenna to get rid of gpsproxy, but this is
expensive because it is bundled with a software.

Other issues: laptop generates heat. Bring a thick leather folder or
clipboard that can be placed on the lap of your navigator to insulate from
heat. His hands are free anyway (to eat, and to type) since he doesn't need
pen, paper and a clipboard to write data, as he is encoding POI's directly
to nroute in real time.

Always bring a backup gps if you have a spare, eg a phone gps. (it's like
your sidearm when your long firearm runs out of ammo). When there are road
obstructions, eg. broken glasses, road repairs, road blocks, etc. You can
supply the missing tracks by going out of the car... walking to the end of
the street and unpassable alleys.

Another advantage of laptop mapping: it also serves as props when explaining
to the guard that you are a mapping-volunteer etc (and not a spy). (With a
smiling face) talk about google, the internet, mapping, ignorace of LGU's,
etc, etc. Normally, the guards don't want to hear your tech stuff and
politics blah blah, he will just let you in. Sometimes, saying that it would
be disadvantageous for their marketing people, subdivision owner, and the
existing residents that their area is not yet on the city map. In under
5mins of convincing, you will normally be allowed to roam freely inside the
gated community. :-)

But I'm telling you, laptop mapping is not for everyday mapping. Dragging
your dc-ac inverter and your roof cables to your car every now and then can
be a hassle. You may want to try using those cheaper bluetooth sirf very
sensitive antenna (no wires, no roof cables, and very long battery life that
is sold on amazon around $45). All you need to do is rig a permanent
clean-12V DC cable plug in your car. Just bring out your laptop from your
bag, place the BT antenna on your dashboard, and you are good to go.

Rally

On Mon, May 18, 2009 at 5:27 AM, Ronny Ager-Wick - Develo Ltd. <
raw at develo.ltd.uk> wrote:

>  Rally,
> This "mobile mapping rig" sounds interesting!
> Any info about that would be great as I'm looking at making a low cost
> setup like that in the near future.
> I've never connected a GPS to a Linux laptop (well, any laptop actually)
> before so it's good to know about what has already been done to avoid
> unnecessary compatibility problems.
> Ronny.
>
> maning sambale wrote:
>
> Did anybody got a picture of the GPS units we used?
>
> @ rem, can I get a copy of Rally's mobile mapping rig (laptop, gps,
> encoder, etc.)
>
> On Sun, May 17, 2009 at 1:54 PM, Andre Marcelo-Tanner<andre at enthropia.com> <andre at enthropia.com> wrote:
>
>
>  Ah great video! suggestion ko lang yung first image yung old map ng tagaytay
> tapos biglang fade to black tapos yung mga tracks natin tapos fade back sa
> new map :)
>
> Eugene Alvin Villar wrote:
>
> Great start for the video! I knew you couldn't get your hands off in trying
> the mapping party video renderer, maning. Hehehe.
>
>
> On Sun, May 17, 2009 at 10:42 AM, maning sambale<emmanuel.sambale at gmail.com> <emmanuel.sambale at gmail.com> wrote:
>
>
>  Mapping party preview video;http://www.flickr.com/photos/esambale/3537844490/
>
> @ ed, Please send me your gpx so I can add them in the video.
>
> To all, please edit this week so the output map in the last segment is
> updated.
>
> Thanks to all who attended.
>
> On Sun, May 17, 2009 at 12:34 AM, Andre Marcelo-Tanner<andre at enthropia.com> <andre at enthropia.com> wrote:
>
>
>  Hi all,
>
> I want to congratulate everyone on a job well done today as we went
> around Tagaytay and mapped the place out. It was a pleasure meeting all
> of you: Maning, Eugene, Ian, Rally, Neil, Ed, and the photographer guy
> from the Inquirer whose name I forgot (sorry!) and the family members
> who were there. It was fun, exciting, and also a great learning
> experience. This is only the beginning and I know we'll be able to do
> more events to bring OSM Philippines to a wider audience and map more of
> the Philippines than anyone else could have imagined.
>
> Best Regards,
>
> Andre
>
> P.S. Pa post ng pics sa Facebook or somewhere :)
>
> _______________________________________________
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>
>          --
> cheers,
> maning
> ------------------------------------------------------
> "Freedom is still the most radical idea of all" -N.Branden
> wiki: http://esambale.wikispaces.com/
> blog: http://epsg4253.wordpress.com/
> ------------------------------------------------------
>
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