I can only partially agree with your statement that multiple GPS traces are more
accurate that some satellite imagery.

Mapping even medium density suburban areas with high resolution imagery is
generally more accurate than GPS, and allows up to add significantly more
detail than any GPS survey could complete. If you think about it, there are
only two errors the picture can have, one of position and of scale. Assuming
that the GPS trace confirms that the Image is correct on the 4 corners of a
chosen square area, the rest in the middle must be pretty much right, or at
least to acceptable tolerances.

My recent experience of mapping Kaduna served as a good example of this.
Kaduna was a town I used to visit frequently some years ago, then I noticed
that it was in high res Yahoo imagery. A number of OSMers started contributing
and generated the map you see below

osm.org/?lat=10.5221&lon=7.4339&zoom=13&layers=B000FTF

Recently I spent three weeks there and devoted my spare time to adding the
details such as street names and amenities. My GPS traces confirmed that
there was no significant error in the positioning of the Sat imagery over
the scale of the town.

However what it did teach me was that there would have been absolutely
no way to have mapped this medium sized town extensively on GPS alone.

There is still much work to be done on Kaduna and only limited resources.

GPS traces give us excellent information for areas not imaged and for
assistance in adding the extra information such as amenties, on the ground
surveying and streetnames. But for high detail work the image is essential.

This essentailly explains why Abuja and Lagos, the capitals of Nigeria
are not on the map yet.

Cheers b

OS maps - they should be good and how long has it taken - too little to late me thinks.

But you know what the OS doesn't have? All the implicit data that OSM maps do, such as the Amenities, free routable maps via Cloudmade etc The OS map is just that, a map, of the UK only.... OSM has the potential to be much more assuming we can keep up the pace of contributions, we should also remember it is also global....

How did I miss this? :(.......Copy that... Ditto - Harry??

Yep - The roads are just the start, the 'Meta Data', the detail of your area is the key to success of this map. Amenities, shops, Supermarkets, Post offices Public toilets, Cash Machines, paths etc. It can all be tagged. Try JOSM for more enhanced editing features over the Web based Potlatch. Good luck and keep up the good work

http://downloads.cloudmade.com/

All the OSMs, Garmin IMGs etc
also for your phone try GPSMID
http://gpsmid.sourceforge.net/

Terrific news for OSM and great forward thinking from Advantage West Midlands. My Father does some work for Yorkshire Forward, an agency with similar regional objectives.

One more example Open Source, GIS and Open Street Map in particular making a difference in this highly competitive world.

Great posting

cheers bri

Public // Private Traces
Hi I understand your desire to remove your home from traces,Using JOSM with the plugin 'EditGPX' will allow you to edit and remove parts of trails that are either noisy and thus misleading, or simply stuff you don't want to put up.
Ideally as much of your traces should be public thus everyone can benefit from the data, but very glad that you are putting back in and have become an OSMer. ( See my entry today @bri%20g/diary/8592 )

RE Maps have a look at the pre-made Cloudmade files here for Garmin / Tomtom etc - http://downloads.cloudmade.com/

Cheers bri

Many thanks for all the comments so far - quick replies are as follows

Bass - I will check out the rock if I can - that part of town is dense and a bit of the beaten track even though it looks so close to the centre

The police college does extend both sides of Independence way at the southern end

Wynndale, Agbo, i don't know where to start, access to Internet for Nigerians is limited or very expensive, and lets face it, mapping, even to the scant detail I work to is time consuming. If I had more time here i would get people on board and interested. i guess it needs a critical mass of people to start contributing, even GPX traces of the main roads would be a great start.

Yep the 'D's are common - but strangely more at nighttime. Update your Legend or Legend HCX software ( sorry I only know Garmins ) as older firmware will not support or find the 'D' signals. Yes it it does improve accuracy. Note there is V3.10 firmware for Garmin HCX users as of last month ( I only noticed yesterday )

Bri

An Old Post of mine ( I have a Legend HCX )

@bri%20g/diary/6486

Took me two days to work out how to convert an OSM map in JOSM into the Garmin IMG format - it is easy when you know how ( and this is just one free method of many ).

Download into JOSM the area you are working on or wishing to update or just want to have a map of in your Garmin. Export the area as an OSM file. Use Mkgmap to convert the OSM into a Garmin IMG file and copy the IMG file onto the GARMIN Micro SD Card:\garmin\gmapsupp.img ( Windows users ).

This allows you to have the current OSM basemap of the area that you need in your Garmin so that you can see what has and more importantly what has yet to be logged in your area - especially in towns and cities which are a challenge.

Mail me if you need further assistance

cheers bri

Doesn't look malicious - there will be mistakes like this - some of us forget that there is a bit of a learning curve on this stuff - especially if using more powerful editors like JOSM - I was responsible for some howlers around Bangladesh when I first started - no one noticed because I was the only one working on it.
An Annoyance for sure - notice there a re no GPS for this area traces to guide a new user -

JOSM is a bit fiddly to begin with - but very powerful once you know its quirks, and yes downloading of large areas is difficult, but you can always 'download along a GPS track'. The ability to add extra nodes on a way is very useful, somethig Potlatch cannot do. For long trails I find it easier to draw a straight line ( especially on a long road ) between two points and then bend the line into shape. Stick with it as the ability to megrge layers, export the OSM and convert this into a Garmin map ( of potentially a whole city ) is perfect.

Merging nodes, making buildings perpendicular and all the Plugins ( WMS / Edit GPX etc ) are great

There is a learning curve but once you are familiar with the tools you wwill not go back

The other tip is to start JOSM with extra memory ( 512 MB or more if you have it ) ( I will post a diary entry for this ).

Cheers bri

Hi - great work re your town - As per Ianlopez comments - POTLATCH, the web based editor is a little limited ( or not as flexible ) as say JOSM for doing detailed editing of town. Out of interest I downloaded your town and noted that the street intersections are not nodes - some of which I have corrected - but this is your town, not mine so I stopped!

There will be a bit of a learning curve with JOSM if you have not used it before but a road being essentially two points can be split into multiple nodes by clicking of the mid sections between nodes, which then turn into nodes themselves. These nodes can be MERGED at intersections with other nodes using the Tools Merge option, thus the junctions are joined and thus nodes.

Why is this important? you ask - I am not entirley sure but presume that it is important for routing programs which use the node information to know if direction changes can be made at intersections. If you have flyovers etc these are marked by bridges or tunnels etc and of course there is no node joining these items where they cross.

Keep up the great work

Cheers bri

RE JOSM moving ways, Ævar Arnfjörð Bjarmason is quite correct, there is a warning dialogue to prevent you moving a whole way - but if I had one change request in JOSM it would be a preference option to never move whole ways - ie by default you cannot move a whole way and as an 'opt in' you can.

Another request would be a preference removing the new confirmation dialogue for merging layers.

I sound like I am moaning now - for what it does JOSM is very very good and very stable - the WMS plugin is great ( a YAHOO imagery overlay ) - great for city editing ) - and other comments talk of the EditGPX which is useful for deleting clusters of points in a CAD environment or GPX trails that are inaccurate due to being in a city etc

cheers bri

Ditto above - I thought coming back to London would be boring after Dhaka - nothing to add - nothing no one else has added - its all been done init? - but NO - loads of detail to add - mused about adding the telephone numbers of public phone boxes - but that would be just too creepy! - As for House numbers - we all have our personal lines that must not be crossed - and that is mine!

Jancis

Nothing beats a personal survey of streets, roads cities etc. Your personal knowledge of a city or town is key and the more that you map the more detail that you will add in a way that no commercial survey can ever do. Also bear in mind that survey data is often out of date, and that OSMers can update information on a daily basis.

Keep up the good work -

Hi Dan - not so long ago ( May / June 09 ) updates were every Wednesday - now 24 hours seems about the norm

Don't forget MKGMAP which allows conversion of downloaded OSM's ( from the website or saved from JOSM etc) to be uploaded to your Garmin HCX Micro SD card
as garmin\gmapsupp.img. Great for going somewhere pre mapped or allowing you to 'audit' an existing place and see what you can add.

Have fun - bri

Grebble - good luck - this is a highly addictive pastime - once you start......
If you need any assistance just ask the group - I am Windows / Josm / GPSBABEL / Garmin HCX user - and upload my OSMs to my Garmin using the converter MKGMAP - all tools listed are Freeware and work well, though it does take a little time to get to grips with it all - I am one of those mapping Dhaka and general Bangladesh ( I have been working here for about a year ) - best regards - bri

Ignis - the HCX are good units - I bought mine two weeks ago and just getting up to speed with it - check out the Garmin webiste - there is new firmware available
for it ( version 3 ). A whole day of logging at 3 second intervals generates a file which is less then 1 M Byte so it will take a while to fill the card - read my entry here on how to upload maps from JOSM to your HCX which is really useful as it chows what has and what has not been mapped

@bri%20g/diary/6486

Cheers brian