[Talk-us-massachusetts] aerial comparisons

[Peter Cooper Jr.]

On 7/15/2022 11:12 AM, hobbit at techno-fandom.org wrote:
> Our default imagery layer in iD seems to be the MassGIS 2021 set, but I've
> found that the 2019 layer seems to have much better visibility.  The newer
> images seem much darker and less distinct.  Do your own observations concur
> with this?  I'm trying to figure out which set is best for spotting where
> "woods" begin and end in a reliable way.

I haven't looked at many places, but if anything the 2021 seems brighter 
and better to me than the 2019 at the spots I'm most likely to map. It 
wouldn't shock me if this was highly dependent on where you're looking, 
though, and exactly which day the plane was flying over the area you're 
looking at.
<https://www.mass.gov/doc/2021-aerial-image-flight-lines/download>

There's also imagery available for several past years. I derived some 
links you can just put into the "Custom" background field of iD that are 
listed in an older version of the MassGIS Wiki page:

<https://wiki.openstreetmap.org/w/index.php?title=MassGIS&oldid=2160851#Imagery_&_Background_Layers>

(Information on this older imagery has been removed from the current 
version of the page, and I'm not ambitious enough to bother restoring 
it, but if someone else wanted to I certainly wouldn't object.)

Sometimes looking at the same spot across multiple years tells you 
something more than just one. But I'm not sure I myself think of "woods" 
as beginning and ending at distinct points (I mean, I might say that "I 
live in the woods" and be correct in a sense, though more accurately I 
live in a house that's surrounded by a lot of woods). Though 
OpenStreetMap's database doesn't deal well with "fuzzy" boundaries, so 
just putting the best guess you can in there of a line is probably as 
good as one can do.

> Turning on the parcel boundaries layer is also fascinating; I had no idea
> those maps were so complex, even in the middle of parks/reservations.

Sometimes parcels are separate but have the same owners, and sometimes 
there are errors in the mapping the assessor's departments provide. But 
it's certainly a nifty tool.

The other really nifty tool, if you haven't seen it already, is the 
LiDAR Shaded Relief map, which is a bit older (from 2010 through 2015) 
but can help one see under the trees and such in a helpful way.

-- 
Peter C.