[OAM-talk] OpenAerialMap questions

[Christopher Schmidt]

I've CCed my response to the OAM-talk list, where further followup can
go.

On Fri, Dec 07, 2007 at 10:40:53AM -0800, Matthew Perry wrote:
> Are any other input formats supported? I'm looking into the licensing
> on the NAIP imagery, which is huge so compressed formats would be
> crucial ... I think it is average 35 GB of imagery uncompressed per
> county.

Anything that GDAL opens is supported, but there are limitations to what
the repository can do anything useful with. (BigTIFF isn't here yet,
etc.) 

Instead of hosting all the data locally, the longer term plan is that
any sizable dataset for which there is a willing provider will be
populated by connecting to a remote WMS. This 'distributed' style of
data loading is something that we're currently working on building the
infrastructure for, after which there is a plan to document how you
should set up your own data -- after that OSGeo/OpenAerialMap is only
responsible for hosting datasets for which there is no willing provider 
available. We have not yet discussed how to scale that aspect of it: my
hope is that we can avoid it for a while, since I think for the most
part there are organizations that are able to provide WMS of most large
datasets, meaning that OAM hosts the small stuff directly, and the big
stuff is shared. 

> What projections are supported for the input data? 

EPSG:4326. 

> Likewise would it
> be possible to support on the fly projection for all layers to get the
> main map in a non-geographic projection? 

The main map is going to continue to be in a geographic projection until
someone provides a reasonable alternative based on the source data being
in EPSG:4326. Reprojecting the source data into mercator looks like
crap. (I know because I've tested it.) 

> What are the storage limits and scalability of the site?

I'm not sure what you mean by 'storage limits and scalability'.
Currently, there is enough space to host any imagery that users could
reasonably upload, but there are plans to change a lot of the
infrastructure once GDAL 1.5 is out: specifically, to using JPG encoding
for storing data, which gains us an order of magnitude in terms of what
we can do with the storage we have available. Again, the goal is not to
have all the data hosted at OAM in the long term, but instead to move to
a situation where the data is hopefully requested via WMS instead.

> Are there going to be any other methods for retrieving the data? WMS?
> WCS? simple web service to download by bbox?

Using with WMS is already covered in links from the site. WCS is not
terribly hard, I don't think, just changing a mapfile, though I'm not
sure if it's useful and I'd prefer to have a use case before offering a
service. Downloading data by bounding box is on the 'Things that are
being pondered' plate, but not near term.

Regards,
-- 
Christopher Schmidt
Web Developer