[OSM-talk] [Talk-us] Sourcing Open Aerial Imagery

Bryan Housel bryan at 7thposition.com
Thu Jul 27 14:23:00 UTC 2017

Thanks Kevin for the followup - sourcing imagery for use in editors is indeed a complicated topic! 

I think the key takeaways (TL;DR):
- there are lots of public sources of aerial imagery available, especially at the us-state level, and we could use help collecting them.
- https://github.com/osmlab/editor-layer-index <https://github.com/osmlab/editor-layer-index> is the place where we coordinate these efforts.
- anybody can lookup what imagery their state makes available, and open an issue on that GitHub repository.

replies inline below:

>> There is lots of public imagery out there, but we need volunteers to:
>> 1. find it in the first place
> I know where it is for my state:
> http://gis.ny.gov/gateway/mg/index.html <http://gis.ny.gov/gateway/mg/index.html>

Great!   The first step is making sure we know about it.  Anybody, even non-technical, can go to https://github.com/osmlab/editor-layer-index <https://github.com/osmlab/editor-layer-index> and open an issue. This is immediately helpful!

(I already did this for the NY State Orthos: https://github.com/osmlab/editor-layer-index/issues/345 <https://github.com/osmlab/editor-layer-index/issues/345>)

>> 2. contact state GIS agencies for permission, if the website does not make
>> license clear
> I have contact information, which I'm not going to share here.
> A template for the letter requesting permission would be very helpful,
> since it's not immediately clear how to describe the intended use to
> an agency. It would be even more helpful to be able to have contact
> information for a resource person to answer any legal questions that
> the agency might have. Surely someone's done this before, for the
> specific case of a state's orthoimagery with this being the intended
> use!

Yes, this can get a bit legally complicated.  I got lucky with NJ, because their “metadata” sheet makes it very clear that the orthoimagery has no use or access constraints, and that attribution is appreciated but not necessary.  Absent of a clear statement like that, we do just need to contact someone in the state GIS office to ask for permission.

TODO:  We don’t have a template letter, or clear guidelines on which imagery licenses are compatible with our use, and we should.  See https://github.com/osmlab/editor-layer-index/issues/166 <https://github.com/osmlab/editor-layer-index/issues/166> .  Like you said in your other email, tracing is very different from importing, so the existing ODBL advice is not what we need.

>> 3. figure out whether the WMS server can serve the imagery (some serve
>> TMS/WTMS tiles that can be consumed directly in iD, others serve WMS which
>> can sometimes be proxied)
>> 4. add the source to editor-layer-index, along with a boundary polygon where
>> the imagery is valid.
> This question seems to be asking for technical details about which I'm
> rather ignorant -
(... snipped ...)
> subtleties that may be obvious to someone accustomed to maintaining
> the software stack, but surely are not obvious to the average
> mapper. When I look at it, I wind up mentally saying, "yeah, maybe one
> of these days I'll have time to tool up with all this stuff.”

You’re absolutely right that a layperson won’t be able to help much with steps 3 and 4, as this requires some technical knowledge.  We could use more volunteers on https://github.com/osmlab/editor-layer-index <https://github.com/osmlab/editor-layer-index> who want to learn about this, and there is a backlog of work for adding imagery sources to the index.

TODO:  I should write up a getting started guide for the editor-layer-index project that can bring people up to speed, including examples.  I think I can put something together that make this topic accessible to anyone with a bit of free time, basic knowledge of how computers talk to each other, and not too afraid of acronyms.

> I'm sorry if I'm sounding harsh here. I really would like to see this
> move forward. Help me to help you!

No apology needed!  Your responses are very helpful, and it made clear some next actions for us to work on..

Thanks, Bryan

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