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Author Topic: Format of Lon/Lat  (Read 3079 times)

The Foster Bear

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Format of Lon/Lat
« on: January 30, 2012, 06:45:50 AM »
I guess this covers a couple of different but related questions. The Foster Preservation Society is trying to map historic buildings, historic cemeteries (153) and ruins of old farms and mills in our town. We are 54 square miles with a low population density of 4600 residents (about 1600 households). The town was originally settled at the turn or the century (1700), it was incorporated originally as Scituate, RI in 1737 and incorporated as a the town of Foster in 1781, dividing Scituate on a north/south line equally.

I would like to make this available through our web site. I am using Basecamp with a GPSmap 62sc to fix the location of the sites, I am then setting them up in Google Earth Pro.

First question is the format of the Lat/Lon coordinates. Since I have a choice of 3 formats, is one most commonly used for automotive GPS units? I can enter any format into Google and it goes right where it is supposed to, but folks with a TomTom or Magellin in their cars may not be able to or understand how to. We want this information useable to everyone.

The second question involves the best program for the intended purpose. For example, I can turn categories on and off in Google and so make the map less cluttered with markers. I can go to a category and pick a single location to turn on.

I have a variety of overlays in Google and find the Topo most useful in seeking the sites. Google's overheads are all blocked by foliage. They don't seem to put up a sattelite view in the dead of winter with bare ground. I can scroll a timeline backwards but when I finally get a clear view, the image won't zoom close enough due to available technology at the time it was created.

I also have overlays of Historic maps from the mid to late 1800s, town maps showing open spaces land with their ownership and historical district maps.

I would like to share these as well, but I love the functionality of Basecamp in being to switch from Auto routes to walking routes when sites are not accessible by auto. I love the ability to set up routes to locations long overgrown. I guess, like a kid in a toy store, I want it all and be able to share it freely. Any thoughts???

Sorry for rambling, The Foster Bear

Boyd

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Re: Format of Lon/Lat
« Reply #1 on: January 30, 2012, 03:27:35 PM »
For starters, you will need to learn the terms of use associated with any imagery you place on your own website. In the case of Google, for example, you couldn't download their imagery and then serve it from your site, you need to use their own interface.

Are you familiar with Historic Aerials? They have imagery going back through the years and some of the old stuff is surprisingly high resolution. It isn't particularly cheap, but if you are only trying to covers a small area it won't be too bad. I purchased a small amount myself for personal project recently.

If nothing else, it's fun to browse with free viewer: http://www.historicaerials.com/aerials.php?op=home

Before you purchase anything however, you should check and see what free imagery your own state and county have available. Some google searches with keywords like

GIS data download orthoimagery orthophotography

in combination with the name of your town and state will probably lead you to some interesting things. You can also see what is available on the USGS seamless server, which would also be free: http://seamless.usgs.gov/website/seamless/viewer.htm

The user interface is a little baffling... zoom in on the area you want, then draw a box with the download tool which will open a data request window. Click Modify Data Request, then scroll way down to the bottom and see what is listed under Orthoimagery and Satellite imagery, where you can check the items you want.

You would need to learn a bit about making maps and have the right kind of software to use this data however.

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Re: Format of Lon/Lat
« Reply #2 on: January 30, 2012, 04:58:46 PM »
Boyd is spot on with all of his content BUT to answer your original question I advocate using DDD.DDDDDD or DDD HH MM.MMM but NOT DDD HH.HHHH.  I think the default on the auto units is DDD.DDDDDD but the optimal would be to provide a download file with points of interest.
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Indrid Cold

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Re: Format of Lon/Lat
« Reply #3 on: February 08, 2012, 08:01:30 AM »
Boyd is spot on with all of his content BUT to answer your original question I advocate using DDD.DDDDDD or DDD HH MM.MMM but NOT DDD HH.HHHH.  I think the default on the auto units is DDD.DDDDDD but the optimal would be to provide a download file with points of interest.
If making a POI file, here is the format: LINK

If you are going to have .gpx files as a download, they will end up being converted to Decimal degrees as per the schema: LINK
« Last Edit: February 08, 2012, 08:08:17 AM by Indrid Cold »

 

anything