[Talk-us] Vegetation/landuse import

Thea Clay thea at cloudmade.com
Thu Dec 3 17:24:17 GMT 2009


Ian,
I totally agree that the import I referenced is not perfect. I really just wanted to show a place that had already completed an import for reference. The points you bring up are very relevant and you were not belittling the effort in the least :) If nothing else we have an example to improve upon. That particular import was done some time ago and a lot has changed on the ground and the dataset is low resolution.

Do you have any recommendations for how we might fix it?
Best,
Thea


On 12/3/09 11:08 AM, "Ian Dees" <ian.dees at gmail.com> wrote:

On Thu, Dec 3, 2009 at 11:01 AM, Thea Clay <thea at cloudmade.com> wrote:
Hi guys,
I am so excited that more land use imports are in the works. They make such a huge visual difference. Check out the border between a state with the import complete and one without: http://www.openstreetmap.org/?lat=34.896&lon=-85.408&zoom=9&layers=B000FTF

Although the lower-detail zooms might look marginally better (I would say they're way too cluttered right now...), the import was not done very well for two main reasons:

1. All of the areas were imported with overlapping edges. This means there is *tons* of duplicate information in the database. I learned my lesson with the counties import: overlapping edge imports like this should be broken apart and use relations for the borders.

2. The resolution of the landuse information is very low. If you zoom in and use Potlatch to see what the aerial images look like, you can see that in most cases the polygons don't come close to matching the actual landuse. in the future, we should make sure that imports are high-enough resolution to be useful in our datasets. 1:24k is the minimum and even that is not useful in some cases.

I'm not trying to belittle the effort, I just want to make sure we don't repeat the same mistakes on other huge imports like this.


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