[Tagging] How is the tag landuse=farmland being used?

[johnw]

Mappers in Japan are tagging seemingly square kilometers of rice fields (or whatever the largest editable area is in ID for some users) and very roughly filling in farmland a to show it at a very low zoom (z12-10) for a good looking map - but so much of the data at high zoom is a 25 year old approximate road & wood area import that looks like spaghetti - so the extra inaccurate polygons roughly placed over the top of the whole mess doesn’t help.  Even when mapping smaller ones, the mappers will draw the polygon so roughly that all the roads, streams, and small houses are inside the farmland polygon - half the time. 

https://www.openstreetmap.org/edit#map=16/35.8678/140.4290 <https://www.openstreetmap.org/edit#map=16/35.8678/140.4290> one farmland polygon there encompasses ~ 200 blocks of rice fields, roughly 10-20 individual fields per block, which is super lazy. it even includes the river. I will fix it as I map up from Narita airport in the coming year, but it is outside the newer updated square of big aerial imagery that is around Narita airport (the big international airport for Tokyo). I wish there was better imagery outside of Tokyo. 

If the field has a drain/stream (since these are rice terraces) I will sometimes adjust the larger ones to include just it, but trim it and make new smaller polygons if it is over a service road or better. But if I am mapping it from scratch, I usually will map each individual block that is separated by a dirt berm or small drain. In some places it is little field by field (about the area taken for 4 houses) because of mixed landuse. As a rule, landuse dictates my mapping. If it’s a house, forest, scrub, or something not farmland, I don’t include it in the polygon. 

However, If I start mapping just rice fields that way now, I might finish the area around Tokyo by the time I’m dead, so making them a bit larger and more inclusive is a balance many mappers figure out for themselves. 

If you can easily map it field by field do so - otherwise try to make a polygon with at least accurate edges of the area. 


Javbw

> On Sep 12, 2015, at 7:13 PM, Dave F. <davefox at madasafish.com> wrote:
> 
> Hi
> 
> How are mappers using the tag landuse=farmland? To map individual fields or large swathes of arable land?
> 
> A user has recently added a large area as a multipolygon relation with woods, villages etc as 'inners' Is this common practice?
> 
> Wiki is precise on this:
> http://wiki.openstreetmap.org/wiki/Tag:landuse%3Dfarmland
> 
> And field redirects to:
> http://wiki.openstreetmap.org/wiki/Vegetation
> 
> My preference is to map individual fields. They can then be individually named or assigned to a particular farm/farmer.
> 
> Thanks
> Dave F.
> 
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