Forgot to mention, if one suspects a geometry error in NVDB one can as a
Swedish citizen (not sure about availability in foreign countries) take
a peek at minkarta.lantmateriet.se and use "terrängskuggning" overlay
with semi-transparancy so you see the road geometry below. The
goverment's 1x1 meter DEM is very accurate measured via diff-gps + laser
from airplane (lidar), and you can usually discern the roads in that.
The DEM is not refreshed as often as NVDB though, so if there are new
roads or a road is moved etc the DEM may be outdated.
On 2025-03-20 21:56, Anders Torger wrote:
While there quality in NVDB does vary (it's a collection of multiple
sources) and geometry simplifications does occur, it's on average very
good. You cannot get the same accuracy from Bing or ESRI imagery, if
you want to get similar precision from ortophoto you would need
lantmäteriet's own. Sure if you have your own diff-GPS system you can
get more precise, but most maps from some sort of orthophoto, usually
with limited elevation correction leading to fairly large positional
errors.
Ideally you should use NVDB + Orthophoto + strava heatmap for sanity
checking + local knowledge where available. I've mapped tens of
thousands of roads in this manner in northern Sweden and quality of
NVDB is very good, while roads mapped on (especially older) ortophoto
in hilly regions can be very far off the mark. In city geometry stuff
get a bit more complicated, because there may be simplifications made
for navigation which may not match with OSM tradition, and there you
need to deviate at times. We have an ongoing manual import project with
documentation of limitations and caveats. You should never import
blindly, that's why the NVDB import project (or rather manual merging)
takes such long time. If you see errors like duplicated geometries,
clearly the mapper hasn't paid much attention to his or her merging
effort. Any source if misused leads to poor results.
It's best to use multiple sources and if working in Sweden NVDB should
for sure be one of them, and if the only positional data you have is
NVDB and an ortophoto from Bing or Esri, NVDB is nearly always better
positioned, with the exception of geometry simplification possibly
occurring on multi-lane roads, or sometimes very new forestry roads
with preliminary geometry and other rare exceptions. Naming of forestry
roads can be wonky in places, as the reporting can be patchy and
approximate depending on forestry company responsible for the
reporting. Naming of roads in cities are usually of very high quality.
The problem with OSM in Sweden is that the coverage can be patchy in
places where there are few active mappers, and some mapping can be
rather outdated. The big cities are usually well covered, or home
cities of super mappers. There are large areas in Sweden which is only
occasionally paid attention to, and there mapping work from people
without access to the ground is needed, and in such a situation using
NVDB in a responsible way as one of the key sources is the best way to
go.
However, if the mapper doesn't really want to make the effort to use
NVDB responsibly and not knowing about its limitations or how you
relate to existing mapping, it's best to not use it of course.
/Anders
On 2025-03-20 13:07, Peter Svensson wrote:
I disagree. The only things that shows exact locations of Swedish roads
are the ground itself. Everything else is approximations and
simplifications which are by definition "not exact". I've lost count of
how many things I've cleaned up after various NVDB import efforts, such
as incorrect names and duplicated/questionable geometries.
I encourage use of other sources than NVDB for mapping missing roads.
With regards,
zvenzzon
Den tors 20 mars 2025 12:31Markku Siipola via Talk-se
<[email protected]> skrev:
Your answers shows you are not aware of NDBD, the National road
database. This source should always be used, and not any source. The
NVDB shows the exact locations of Swedish roads. It's waste of time of
not using this db.
Den 2025-03-20 kl. 08:38, skrev Valeria Yukovich via Talk-se:
Hello, Snusmumriken! Thank you for the questions.
We will be using available sources which are appropriate for mapping on
OSM (satellite and street-level imagery, for example). Besides that, we
will be also using Mapbox telemetry data and GPS traces in cases when
there is limited evidence. More information about Mapbox telemetry data
can be found here: https://www.mapbox.com/telemetry [1].
Speaking about our experience with other countries, we mostly
encountered missing roads in newly built residential areas and around
commercial objects, which we did not map in cases if the evidence
(street-level imagery or up-to-date satellites, information from the
telemetry) was not enough for mapping.
On Wed, Mar 19, 2025 at 12:18 PM Snusmumriken
<[email protected]> wrote: On Tue, 2025-03-18 at 16:46
+0300, Valeria Yukovich via Talk-se wrote:
Hello from the Mapbox team!
Our team has been mapping missing roads since May (as described
here: https://community.openstreetmap.org/t/mapbox-organized-editing-
missing-roads/113678) and currently we are preparing to expand the
effort to Sweden.
Hi
I have basically two questions:
- What sources will you be using in Sweden?
- What are the most common problems you've encountered in other
countries?
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Links:
------
[1] https://www.mapbox.com/telemetry
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