USGS maps and aerial photos for PA

[John Swindler]

Concerning topo maps, stumbled across another yesterday on link from 
ancestry.com:  called "topozone"  Loads at glacial speed, but seems to have 
topo maps for all states.  For those of us into "industrial archaeology":
- The Lancaster topo map showed the Manheim trolley line as an abandoned 
railroad from Delp Road to East Petersburg.
- Same goes for Hagerstown and Frederick's Thurmont line.
- Oley Valley line between Reading's Carsonia Park to just south of Oley 
shown as dashed line (possible power line). (Now I know where to look for 
some bridge piers)
- West Penn in vicinity of Hecla Jct. shown as abandoned railroads, but one 
needs to know what is really ex-railroad and what is ex-West Penn. Also, 
West Penn embankment on north side of turnpike overpass south of Hecla very 
evident in topo.
- Map for south Pittsburgh does not show Drake line as existing, but easy to 
follow terrain features from Washington Jct. to Drake Loop and onto route 
19. Same goes from Simmons Loop to top of hill above Finleyville.
- Also easy to pick out Liberty Bell route near Coopersburg.

Concerning USGS website, it includes link to Microsoft Terraserver site, 
which was recently changed to include both aerial photos and topo maps.  But 
coverage is not complete, and image not as sharp as "Topozone" site, but 
loads much quicker.

Other relics visible from aerial photos on the internet are the Marietta 
trolley bridge piers north of Chickies Creek and string of about a dozen 
bridge piers on Oley Valley line east of Oley. More often, the aerial photos 
may reveal the probably path of an old trolley line as a tree line.  For 
more modern viewing, the San Diego east line shows up very plainly in the 
aerial photos.

The topo maps and aerial photos are just a couple additional tools for those 
who are intrigued by trying to discover what evidence remains of the trolley 
era.  Sure does help to look in the right area!

John S.


>From: Derrick J Brashear <shadow at dementia.org>
>Reply-To: pittsburgh-railways at dementia.org
>To: pittsburgh-railways at dementia.org
>Subject: USGS maps and aerial photos for PA
>Date: Sun, 13 Feb 2000 13:56:26 -0500 (EST)
>
>This is specifically for Bob Dietrich, but as others may be interested and
>it's at least theoretically on topic I'll share it with all of you.
>
>Now that I typed it I see it's a big wordy, and I'm sorry about that. As
>we discovered yesterday you still find interesting stuff, like a set of
>piers outside Millersville (near Lancaster) from a line which is of course
>long since gone.
>
>The Pennsylvania Spatial Data Access system is hosted at the Deasy
>Geographics Lab at Penn State. Their home site is http://www.pasda.psu.edu
>and they have an archive with includes all 7.5' series quadrangles for PA,
>both collared and collarless, and all of the aerial photo quadrangle
>quadrants (a.k.a. USGS DOQs)
>
>Quadrangle maps can be found in
>ftp://penne.deasy.psu.edu/pub/pasda/drg24k
>and versions of these with collars clipped in
>ftp://penne.deasy.psu.edu/pub/pasda/drg24k-c
>
>The files are zip files named for the quadrangle contained therein, e.g.
>lancaster_pa.zip. Unzipping the file will give you generally a .tif file
>and a .tfw file. Some may also have a .met or .mgd file, which are
>metadata (like the date of the quadrangle). The .tif file is a TIFF image
>file with GeoTIFF tags added. The GeoTIFF tags are essentially
>georeferencing information, sufficient such that a suitably equipped piece
>of software can know the coordinates of any point in the image.
>
>For Windows users (of which I am not one) I know of at least 2 free data
>viewers which can handle this information (note that any TIFF viewer can
>be used if you don't care about the georeferencing, and since TIFF is a
>standard format your Windows system might come with a viewer. I don't
>know)
>
>http://mcmcweb.er.usgs.gov/viewers/dlg_view.html is the USGS's map viewer
>software.
>
>http://www.esri.com/software/arcexplorer/index.html is from ESRI, the
>largest GIS software maker probably in the world.
>
>The latter package is probably more refined.
>
>The latter package can also be used to view all of the aerial photos. They
>come in 3 formats. One is the aforementioned .tif/.tfw style. The other 2
>are ESRI "proprietary" formats, called .bil and .bsq (band interleaved by
>line and band sequential). .bil and .bsq files come with a .hdr file with
>some header information in it.
>
>The aerial photos can be found at
>ftp://penne.deasy.psu.edu/pub/pasda/doq
>
>The files are again zip files, this time named by a quadrant of a 7.5'
>quadrangle, e.g. lancaster_pa_nw.zip. They will contain either a .tif/.tfw
>pair or a .hdr file with a .bil or a .bsq file.
>
>The resolution of the 7.5' quadrangles is 1 pixel equal to about 2.1
>meters squared. The resolution of the DOQs is 1 pixel equal to 1 meter
>squared.
>
>I expect to be able to burn custom CDs of these in the future, as I'm am
>about 3/4 of the way through having a complete set of DOQs downloaded, and
>I already have virtually all of the mid-Atlantic region's 7.5' quadrangles
>downloaded. With non-standard TIFF "deflate" compression a DOQ file is
>about 30 megs, meaning about 14 can be fit on a CD, or the equivalent of 3
>and a half 7.5' quadrangles worth. When I get to the point where I have
>all the maps and can burn CDs useable under Windows I will mention it to
>the list, and can hopefully make up CDs for those of you who have some pet
>area you're after. Oh, and I'll have to provide a TIFF inflator for you.
>
>Theoretically this means that all of West Penn coke region territory could
>be covered on 2 cds. I intend to try it. Note though, that even with 1m x
>1m resolution it's not obvious from the air where the main line ran after
>leaving 119 before it reached the street again in Dunbar (which is to
>say, the stretch where it crossed the PRR, B&O and WM in short order)
>
>Must of the same data is available from the Microsoft Terraserver
>(http://terraserver.microsoft.com), but they don't yet cover all of PA
>last I checked, their data is tiled into small JPGs, which means if you
>want a large area you either have to capture an image or paste them
>together, and at least one of the satellites they got source image data
>from seems to have been a bit wacky when it passed near my house and
>potentially elsewhere: a nearby corner doesn't mate nicely.
>
>Note that all USGS data is freely redistributable, since your tax dollars
>bought it.
>
>You can send me any questions you have on the subject; As you might have
>guessed this is an area of personal interest to me;-)
>
>-D
>
>
>

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