On Tue, May 22, 2012 at 10:28 AM, Joe Larson <[email protected]> wrote:
> hello OAM community!
>
> We have processed public domain 12-inch imagery acquired last year,
> for our entire County & significant areas of 6-inch imagery through
> the OpenAerialMap workflow. About 50GB worth.
>
> We have a place to house the imagery, at Cal Poly - on a Computer
> Science Department SAN.
>
> Some questions have come up, I wanted to ask those here. Also wanted
> to have some of you `pro's` take a look at some sample tiles.
>
> Here's a 6-inch:   http://dl.dropbox.com/u/38388156/5622_2426.tif
> Here's a 12-inch: http://dl.dropbox.com/u/38388156/5622_2426.tif

As best as I can tell, the above links are exactly the same.

> One question that's come up..The imagery's original SRS is EPSG:2229
> and we think we should have applied a step in the creation-workflow to
> add an alpha with the warp to 4326. This would get rid of the black
> collars? And does this seem necessary?

I see you do have a nodata mask for 5622_2426.tif which seems to be
working properly for the above file so I'm guessing you do not need
an additional alpha mask.

> Not sure if this is useful, but we loaded a draft-set of the imagery
> into a MapServer/MapProxy WMS - here's what it looks like
> http://mapproxy.slocountyfire.org/demo/?srs=EPSG%3A4326&format=image%2Fjpeg&wms_layer=slocounty-12in

I do see painful tile edge white slivers that seem to indicate some
sort of masking problem.  I'm not sure if it is in a processing step
after the 5622_2426.tif or in MapServer.

Modern MapServer should honour the nodata mask in the .tif file
you provided.

I will note that your overviews appear to be created with nearest
neighbour downsampling which, I think, is not as visually pleasing
as averaging.  Consider using -r average when you run gdaladdo.

Nice to see a great dataset so nearby!

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, [email protected]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Software Developer

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