Changeset: 49549101
Nepal (east), tidy over-noded natural=wood
Closed by bdiscoe
Tags
created_by | JOSM/1.5 (12275 en) |
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source | Bing |
Discussion
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Comment from marek kleciak
Stop destroying detailed map using generalization tools. In developing countries like Nepal eactly map can save human life. Please first ask, then act.
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Comment from SomeoneElse
Hi Marek,
Can you please explain what were the actual problems caused by this changeset and the others on which you have similarly commented?
Also, you may find that that using emotive language such as "stop destroying" is less effective at communicating what you want to get across than a simple question asking why a certain change was made.
Best Regards,
Andy Townsend, on behalf of OSM's Data Working Group. -
Comment from imagico
I would like to add that what bdiscoe did here was not in any way destroying a detailed map. He removed nodes which had a very little influence on the overall geometry because they were almost exactly in the middle between the next and the previous node. See http://nrenner.github.io/achavi/?changeset=49549696
Since the original mapping here contains a mixture of too few and too many nodes (too few in the sense that there are many sharp corners in the mapping which do not actually exist in reality, too many in the sense that the influence they have on the shape is small compared to the level of detail of mapping) this is a sensible step. If it is worth the trouble is a different question of course.
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Comment from SomeoneElse
For info, see also https://www.openstreetmap.org/user_blocks/1385 .
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Comment from bdiscoe
For what it's worth, I wrote OSM messages to marek kleciak explaining these edits, and even described the detailed steps he can do in JOSM to do the cleanup himself.
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Comment from marek kleciak
We are in touch with bdiscoe now. I wrote him about reasons for this mapping. We have opportunity to make an very exactly example for nepali authorities and show the results during SOTM Asia 2017. All old, too less forest areas should be removed/modified. I hope for help of you all: The goal would be to introduce our map for the administrative purposes. In Nepal we have an special situation because of activity of KLL. So we can help from outside with precisely mapping.
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Comment from imagico
Who is 'we' here?
Keep in mind that planning and organizing of mapping activities and development of mapping conventions should be public.
Although there is not yet a formal policy on organized mapping activities it is good practice to document such activities and reference this in changeset comments/tags. If you develop a mapping system for woodlands in Nepal for others to take cue from this needs to be documented and open for scrutiny, critique and modification by other mappers.
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Comment from marek kleciak
We, is Kathmandu Living Maps. As you probably know from german forum I do a lot for Nepal and try to inform communities in Germany and Poland about recent situation there.
What you wrote about mapping activities is a part of old OSM communication problem, but you´re absolutely right, I should write a comment to the changesets. -
Comment from marek kleciak
Hi everybody, KLL wil post information about this Project in the Wiki Project Nepal. Meanwhile I analyzed approach described by bdiscoe. Using generalization factor of 1.0 m we change the areas of smaller Farmlands in forests by up to 5%. I suggest the generalization factor of. 0.3m which make changes by around 1% od smaller areas. The goal of this projest is to achiee a map with whole landuses like:
- Forest
- Scrub
- Farmland
- Residential
- Scree
- Sand
- WaterThis can allow the observation of this area and analyzing it.
An example are climatic changes and destruction of forest and water areas.
Calculation of farmers productivity
With other words, an new paradigm of OSM use. -
Comment from SomeoneElse
@marek - having nodes closer together doesn't make for a map that matches reality better; it just makes it more difficult to edit. If you've got some specific examples perhaps write it up as a diary entry?
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Comment from marek kleciak
Absolutely. This matter needs an proposal and discusion of the community.
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Comment from bdiscoe
Marek the starting point of your analysis is incorrect. It assumes that the existing, hyper-noded wood areas are precisely correct with no uncertainty or error bars. Consider the factors involved - imprecise criteria, human variability, seasonality, poor resolution, loose rectification, etc. it is absurd to claim certainty or accuracy within 20%, or for some parts of Nepal with even worse imagery, 50%. A change of 5% in the area only reflects the mathematical adjustment due to a larger number of convex than concave polygons in the digitization. It is completely dwarfed by the uncertainty.
Apply a strong simplification to these bad landuse polygons, or the community will have to do it for you (again).
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Comment from marek kleciak
Ben wrote: imprecise criteria, human variability, seasonality, poor resolution, loose rectification.
We have Premium Digital Globe images from last year for whole Nepal. Factors like human variability or seasonality are general for all OSM maps. Only activation of the community AND in this case local authorities, can help with such problems. Let´s talk with local community about.
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