Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Karl Newman]

On Wed, Apr 29, 2009 at 5:31 AM, Lambertus  wrote:

> Maarten Deen wrote:
> > Lambertus wrote:
> >> Maarten Deen wrote:
> >>> Not to diminish your work on that front, but I find the tilelayout on
> >>> your site very strange. Of course it is a work of the splitter, but I
> >>> would opt for a manual layout, guided by an initial automated process.
> >>>
> >> Please forgive me for relying on the automated Splitter layout
> >> mechanism as I have no intention to manually divide the world into 500
> >> tiles (317 America + 182 Europe/Asia/Africa/Oceania currently).
> >> Optimizing the tiles would result in even more, so you'd be talking
> >> about e.g 750 tiles.
> >
> > I'm certainly not complaining about your work. It's the reason why I
> > bought a Garmin Nüvi and not a TomTom.
> >
> See Garmin...this is why you need to publicize your map format :-)
>
> >> Needless to say: patches welcome ofcourse. The definition files for
> >> Splitter are:
> >> - 
> >> http://planetosm.oxilion.nl/~lambertus/america.list
> >> - 
> >> http://planetosm.oxilion.nl/~lambertus/eurasia.list
> >>
> >>> IMHO the strategy that the Mapsource tiles use is much more logical.
> >>> Take one big tile, if that has too many nodes, split it in half
> >>> horizontally, if that has too many nodes split it in half
> >>> vertically... repeat until you have a sufficient small amount of nodes.
> >>>
> >> This strategy is afaik exactly what Splitter does.
> >
> > Then it does it in a strange way. I'm sure you've noticed that the edges
> > of the tiles don't line up by just a few 1/100th of a degree in a lot of
> > places. That is inconsistent with a strategy of dividing a tile in half
> > if it has too many nodes.
> > E.g. tiles 63240113 and 63240116. One has a north border of 51.679688,
> > the other  51.635742. And then two tiles further east, 63240120 has a
> > north border of 52.679688 again.
> >
> Well, maybe not exactly in half, but the idea is the same. Afaik, the
> reason why Splitter doesn't split exactly in half is that there is less
> chance that a polygon is present in too many tiles.
>
> > BTW: have you seen that Mapsource draws the maps as overlapping? I've
> > attached a screenshot of how Mapsource displays maps 63240105 (yellow),
> > 63240175 (blue, continuing to the top) and 63240179 (green).
> > They all overlap eachother. According to their definitions, they should
> > not overlap, but mapsource apparently disagrees.
> > Any idea why that is?
> >
> I've seen this with topo maps made with older versions of Mkgmap as
> well. This might be a bug in Mkgmap or a misunderstanding of the Garmin
> map format but I don't think it's harmful though.
>

Probably the reason for the overlap is nodes shared on a polyline which
crosses a tile boundary, to prevent gaps. These shared nodes would extend
the boundaries of each tile somewhat into the space of the neighboring tile.
Otherwise, each tile would have to have a node exactly on the border, and
the map resolution might not allow that. Shared nodes are required in
routable maps (the shared nodes are marked as "external" to allow routing
across tiles).

Another reason I just thought of, which may explain why the overlap looks so
large (larger than could be explained by shared nodes) is possibly the map
projection used by MapSource. The projection might distort the map
boundaries from a rectangle into something warped, but for simplicity
MapSource only draws a straight line (not great circle) between the map
boundary segments.

Karl
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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Lambertus]

Maarten Deen wrote:
> Lambertus wrote:
>> Maarten Deen wrote:
>>> Not to diminish your work on that front, but I find the tilelayout on 
>>> your site very strange. Of course it is a work of the splitter, but I 
>>> would opt for a manual layout, guided by an initial automated process.
>>>
>> Please forgive me for relying on the automated Splitter layout 
>> mechanism as I have no intention to manually divide the world into 500 
>> tiles (317 America + 182 Europe/Asia/Africa/Oceania currently). 
>> Optimizing the tiles would result in even more, so you'd be talking 
>> about e.g 750 tiles.
> 
> I'm certainly not complaining about your work. It's the reason why I 
> bought a Garmin Nüvi and not a TomTom.
> 
See Garmin...this is why you need to publicize your map format :-)

>> Needless to say: patches welcome ofcourse. The definition files for 
>> Splitter are:
>> - http://planetosm.oxilion.nl/~lambertus/america.list
>> - http://planetosm.oxilion.nl/~lambertus/eurasia.list
>>
>>> IMHO the strategy that the Mapsource tiles use is much more logical. 
>>> Take one big tile, if that has too many nodes, split it in half 
>>> horizontally, if that has too many nodes split it in half 
>>> vertically... repeat until you have a sufficient small amount of nodes.
>>>
>> This strategy is afaik exactly what Splitter does.
> 
> Then it does it in a strange way. I'm sure you've noticed that the edges 
> of the tiles don't line up by just a few 1/100th of a degree in a lot of 
> places. That is inconsistent with a strategy of dividing a tile in half 
> if it has too many nodes.
> E.g. tiles 63240113 and 63240116. One has a north border of 51.679688, 
> the other  51.635742. And then two tiles further east, 63240120 has a 
> north border of 52.679688 again.
> 
Well, maybe not exactly in half, but the idea is the same. Afaik, the 
reason why Splitter doesn't split exactly in half is that there is less 
chance that a polygon is present in too many tiles.

> BTW: have you seen that Mapsource draws the maps as overlapping? I've 
> attached a screenshot of how Mapsource displays maps 63240105 (yellow), 
> 63240175 (blue, continuing to the top) and 63240179 (green).
> They all overlap eachother. According to their definitions, they should 
> not overlap, but mapsource apparently disagrees.
> Any idea why that is?
> 
I've seen this with topo maps made with older versions of Mkgmap as 
well. This might be a bug in Mkgmap or a misunderstanding of the Garmin 
map format but I don't think it's harmful though.


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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Maarten Deen]

Lambertus wrote:

Maarten Deen wrote:

Lambertus wrote:

Splitter tries to automatically determine the maximum tile size for a
specific area but the data in that area is giving Splitter false clues.
This might be caused by e.g. a combination of many POI's but few roads.


Not to diminish your work on that front, but I find the tilelayout on your site 
very strange. Of course it is a work of the splitter, but I would opt for a 
manual layout, guided by an initial automated process.


Please forgive me for relying on the automated Splitter layout mechanism 
as I have no intention to manually divide the world into 500 tiles (317 
America + 182 Europe/Asia/Africa/Oceania currently). Optimizing the 
tiles would result in even more, so you'd be talking about e.g 750 tiles.


I'm certainly not complaining about your work. It's the reason why I bought a 
Garmin Nüvi and not a TomTom.


Needless to say: patches welcome ofcourse. The definition files for 
Splitter are:

- http://planetosm.oxilion.nl/~lambertus/america.list
- http://planetosm.oxilion.nl/~lambertus/eurasia.list

IMHO the strategy that the Mapsource tiles use is much more logical. Take one 
big tile, if that has too many nodes, split it in half horizontally, if that has 
too many nodes split it in half vertically... repeat until you have a sufficient 
small amount of nodes.



This strategy is afaik exactly what Splitter does.


Then it does it in a strange way. I'm sure you've noticed that the edges of the 
tiles don't line up by just a few 1/100th of a degree in a lot of places. That 
is inconsistent with a strategy of dividing a tile in half if it has too many nodes.
E.g. tiles 63240113 and 63240116. One has a north border of 51.679688, the other 
 51.635742. And then two tiles further east, 63240120 has a north border of 
52.679688 again.


BTW: have you seen that Mapsource draws the maps as overlapping? I've attached a 
screenshot of how Mapsource displays maps 63240105 (yellow), 63240175 (blue, 
continuing to the top) and 63240179 (green).
They all overlap eachother. According to their definitions, they should not 
overlap, but mapsource apparently disagrees.

Any idea why that is?

Maarten
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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Lambertus]

Maarten Deen wrote:
> Lambertus wrote:
>> Splitter tries to automatically determine the maximum tile size for a
>> specific area but the data in that area is giving Splitter false clues.
>> This might be caused by e.g. a combination of many POI's but few roads.
> 
> Not to diminish your work on that front, but I find the tilelayout on your 
> site 
> very strange. Of course it is a work of the splitter, but I would opt for a 
> manual layout, guided by an initial automated process.
> 
Please forgive me for relying on the automated Splitter layout mechanism 
as I have no intention to manually divide the world into 500 tiles (317 
America + 182 Europe/Asia/Africa/Oceania currently). Optimizing the 
tiles would result in even more, so you'd be talking about e.g 750 tiles.

Needless to say: patches welcome ofcourse. The definition files for 
Splitter are:
- http://planetosm.oxilion.nl/~lambertus/america.list
- http://planetosm.oxilion.nl/~lambertus/eurasia.list

> IMHO the strategy that the Mapsource tiles use is much more logical. Take one 
> big tile, if that has too many nodes, split it in half horizontally, if that 
> has 
> too many nodes split it in half vertically... repeat until you have a 
> sufficient 
> small amount of nodes.
> 
This strategy is afaik exactly what Splitter does.


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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Maarten Deen]

Lambertus wrote:
> Splitter tries to automatically determine the maximum tile size for a
> specific area but the data in that area is giving Splitter false clues.
> This might be caused by e.g. a combination of many POI's but few roads.

Not to diminish your work on that front, but I find the tilelayout on your site 
very strange. Of course it is a work of the splitter, but I would opt for a 
manual layout, guided by an initial automated process.

IMHO the strategy that the Mapsource tiles use is much more logical. Take one 
big tile, if that has too many nodes, split it in half horizontally, if that 
has 
too many nodes split it in half vertically... repeat until you have a 
sufficient 
small amount of nodes.

Regards,
Maarten


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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Lambertus]

Splitter tries to automatically determine the maximum tile size for a
specific area but the data in that area is giving Splitter false clues.
This might be caused by e.g. a combination of many POI's but few roads.

One way of working around those problem areas is to force Splitter to
dimension the tiles so that they fewer nodes using the --max-nodes
option. This is what I've done and now most of the world is rendered by
Mkgmap without problems, except the ones in Denmark.

Carsten Nielsen wrote:
> Very nice, but what is the reason for exactly those maps not beeing
> generated yet ?
> 
> Carsten Nielsen
> 
> Lambertus skrev:
>> I plan to have those missing tiles for Denmark on
>>  fixed with the next update
>> which is within a week.
>>



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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Lambertus]

I plan to have those missing tiles for Denmark on 
 fixed with the next update 
which is within a week.

Carsten Nielsen wrote:
> Why is there nolonger any OSM based Garmin maps (img), available for
> download ?
> 
> I am just wondering why all the usual places for download of maps
> nolonger are providing
> files for Denmark ?
> 
> http://www.osm4you.com/Europe/Denmark/denmark_gmapsupp_img.zip   Only
> 330 bytes and useless file
> http://garmin.na1400.info/routable.php  As the only place in
> europa no files area vailable for Denmark
> http://emexes.powweb.com/osm/ Is totally gone
> 
> This is not a big problem for me because I can create my own maps with
> mkgmap, but it made wonder
> about som problems I have had.
> 
> I have made my own garmin map files for some time (I want a bit more
> than just denmark) without problems,
> but after someone made a major import of public address information I
> was unable to create maps
> with mkgmap (even when using the splitter). I have made a little program
> that remove all the address nodes
> from my downloaded osm files, and now I can create garmin maps again.
> 
> Is it the same problem that hit me which tis causing problems at themap
> sites aswell ?
> 
> Are there anybody else out there that can make garmin maps of denmark
> with mkgmap ?
> 
> ablansinger  / Carsten Nielsen
> 
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Re: [OSM-talk] OSM maps of Denmark for download to Garmin devices

[Ed Avis]

Carsten Nielsen  toensberg.dk> writes:

>Why is there nolonger any OSM based Garmin maps (img), available for
>download ?

Have you tried ?

-- 
Ed Avis 


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[OSM-talk] OSM maps of Denmark for download to Garmin devices

[Carsten Nielsen]

Why is there nolonger any OSM based Garmin maps (img), available for
download ?

I am just wondering why all the usual places for download of maps
nolonger are providing
files for Denmark ?

http://www.osm4you.com/Europe/Denmark/denmark_gmapsupp_img.zip   Only
330 bytes and useless file
http://garmin.na1400.info/routable.php  As the only place in
europa no files area vailable for Denmark
http://emexes.powweb.com/osm/ Is totally gone

This is not a big problem for me because I can create my own maps with
mkgmap, but it made wonder
about som problems I have had.

I have made my own garmin map files for some time (I want a bit more
than just denmark) without problems,
but after someone made a major import of public address information I
was unable to create maps
with mkgmap (even when using the splitter). I have made a little program
that remove all the address nodes
from my downloaded osm files, and now I can create garmin maps again.

Is it the same problem that hit me which tis causing problems at themap
sites aswell ?

Are there anybody else out there that can make garmin maps of denmark
with mkgmap ?

ablansinger  / Carsten Nielsen

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