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Geocoding - Setting the Accuracy

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#1 MVS

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Posted 30 July 2015 - 03:35 AM

I cannot see a previous thread on this issue (but I may be wrong).

 

It seems to me that it is great when you can accurately identify a specific place for an activity, event, specific building or even down to a specific location for, say, a gravestone; and then record that in Rootsmagic.

 

However, there are lots of activities where only a general location is known and recording a precise latitude and longitude through geocoding gives the impression of an accuracy that is not actually known. 

 

An example might be recoding an old family photograph; I can record an event and give a date range (between x and y) to show that "uncertainty" of the date; but if I know the location was near the town of Newhaven, Sussex and actually enter Newhaven, Sussex the geocoding will ascribe a very accurate location to the centre of the town that is not true.  If I decide just to put the country of Sussex as the location then the geocode just points to the centre of the county. 

 

So I think that geocoding could be enhanced by allowing an additional field to enable to users to record the "uncertainty" of the precise location in the same way that putting "about 1923" or "between 1921 and 1925" allows us to record the uncertainty of dates. Perhaps we need a "within x miles/kilometres/yards/metres" field as an adjunct to the geocode? 

 

Potentially this could be used in future mapping enhancements to show an "area" rather than a "pin" location for such an entry?  This would make it easy to see the difference between a "pin" that showed a precise geocode was known (ie a specific building, point of interest, gravestone, church etc) and an "area" which reflected a degree of certainty but not the precise location.

 

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#2 mjashby

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Posted 31 July 2015 - 03:40 AM

But geocoding is always precise by definition; and can only be useful for interfacing with and recording locations precisely on modern maps provided by other developers, e.g. Google. The display dependancy is controlled by what facilities the individual map provider allows through its interface with other software, so I am not really clear how you could visually map uncertain locations/areas.  The conundrum: Modern mapping sites are specifically developed to provide pointers to modern (current) locations and require precision. - None are (currently) designed specifically for historical/generalised mapping purposes and so all genealogy software can to is provide the best possible interpretation of where events took place by overlaying historic detail on modern maps, using the specific facilities and controls of the mapping site.

 

Perhaps there could be an option/flag to exclude individual events from being mapped, but then you also lose any visual approximation of where the event occurred.


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#3 MVS

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Posted 31 July 2015 - 06:20 AM

RM and many other mapping applications just use a one type of marker display.  However there are other sites which use a lot more of the mapping features that are available. A quick look at, for example, the Google Maps API shows that it is possible to set individual styles for the location markers.  Therefore it is perfectly possible to show a small, marker in a specific colour to illustrate this is a precise location and also show other markers in different colours and different sizes to show "this is the rough area as defined in RM" for this event.

 

I have seen just this type of display in a Microsoft CRM mapping extension for Bing Maps so if the additional "accuracy" data was stored in RM the code can be constructed to show the difference between a precise, known location and an approximate one  (Indeed a quick google search on "Bing Pushpin control" shows sample code needed to put custom markers on a map).  The different sizes and features of pushpins can be a computed size or a different image; there are many options.

 

Although the scale of this marketing image from a Bing maps display is not quite what we need from genealogy the example here shows the type of thing that can be easily achieved : http://d1ftgt94wd5jm...cubes_qmapr.jpg.  Or another one here, again with the wrong scaling, but a general idea of how things can be displayed in different sizes -  http://bingblog.blob...ip_image024.jpg.

 

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#4 TomH

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Posted 31 July 2015 - 06:09 PM

It is one thing to have a marker that is sized proportionally to some value and quite another to define an area that could factor into calculations such as events near a given geo location. RootsMagic's own feature for reporting events near a location requires the user to enter a radius. All pinpointed events falling within the circle defined by that radius and the given coordinate are then included in the report; all those outside are excluded. So what if each event had a radius parameter related to one's uncertainty about the location? Then both graphical display and events near a location could take that radius into account.

Of course that is not ideal, given that no city, county, state, province, country is in the shape of a circle. A much higher level of sophistication could be developed using GIS technology (Geographic Information Systems).

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#5 MVS

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Posted 04 August 2015 - 09:28 AM

That is a fair point and I am not sure what either Bing or Google offer in terms of searching for the proximity of "areas" rather than "points".  However, even if the mapping technology does not yet easily exist at this level, I still think there is a valid argument for allowing the user to record within RM that the location is approximate rather than known to be 100% accurate (e.g. the unmarked grave is in this cemetery - but the precise location is not known).

 

MVS



#6 Renee Zamora

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Posted 04 August 2015 - 10:32 AM

There are Place and Place Detail notes. You could note that the geocode is approximate rather than 100% accurate in these situations. 


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#7 CADesertRat1

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Posted 13 November 2016 - 03:10 AM

I cannot see a previous thread on this issue (but I may be wrong).

 

It seems to me that it is great when you can accurately identify a specific place for an activity, event, specific building or even down to a specific location for, say, a gravestone; and then record that in Rootsmagic.

 

However, there are lots of activities where only a general location is known and recording a precise latitude and longitude through geocoding gives the impression of an accuracy that is not actually known. 

 

An example might be recoding an old family photograph; I can record an event and give a date range (between x and y) to show that "uncertainty" of the date; but if I know the location was near the town of Newhaven, Sussex and actually enter Newhaven, Sussex the geocoding will ascribe a very accurate location to the centre of the town that is not true.  If I decide just to put the country of Sussex as the location then the geocode just points to the centre of the county. 

 

So I think that geocoding could be enhanced by allowing an additional field to enable to users to record the "uncertainty" of the precise location in the same way that putting "about 1923" or "between 1921 and 1925" allows us to record the uncertainty of dates. Perhaps we need a "within x miles/kilometres/yards/metres" field as an adjunct to the geocode? 

 

Potentially this could be used in future mapping enhancements to show an "area" rather than a "pin" location for such an entry?  This would make it easy to see the difference between a "pin" that showed a precise geocode was known (ie a specific building, point of interest, gravestone, church etc) and an "area" which reflected a degree of certainty but not the precise location.

 

MVS



#8 CADesertRat1

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Posted 13 November 2016 - 03:23 AM

I couldn't find a forum for this subject--yours was the closest.  I tried to manually add latitude and longitude on the "Edit--Place list" page. The space turned pink and then rolled all the numbers back to 0 (zero). My ancestors liked to live in out of the way places where there was no population center nearby. I went out of my way to obtain their latitude and longitude.  How can I add them to the places you don't have covered?  CADesertRat1



#9 Jerry Bryan

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Posted 13 November 2016 - 07:35 AM

I can't replicate your scenario where the space turned pink and then rolled all the numbers back to 0. In my experience, you can edit either a Place or a Place Detail and having done so you can manually add GPS coordinates or manually change existing GPS coordinates just fine.

 

It seems to me that the problem rather is that each Place or each Place Detail can only contain a single set of GPS coordinates. For example, suppose you have Augusta County, Virginia in your database and it is already geocoded by RM. The coordinates will be exact, but will be at some rather amorphous place somewhere at or near the geographic center of the modern day county. No degree of uncertainty will be included in the coordinates, and the coordinates will not reflect the approximate center of the county at any time other than the present. But suppose your exact GPS coordinates are for the Smith family farmhouse on the old family farm in Augusta County in 1750. If you change the coordinates for Augusta County to the exact coordinates of the farmhouse, then the GPS coordinates will be changed to that of the farmhouse 1750 and will be changes for all references to Augusta County. To avoid the problem you would have to do something like add old Smith family farmhouse as a Place Detail under August County, Virginia and geocode the new Place Detail. Or if you prefer not to use Place Details, you would have to add a new place called something old Smith family farmhouse, Augusta County, Virginia and then enter you exact coordinates for that place.

 

I'm using Augusta County because it very nicely illustrates some of the many perils of geocoding. I have ancestors who owned property in what was then Augusta County. I have the exact coordinates of the land, but the property now lies in modern day Rockingham County, Virginia. And the problem is even worse than that because a 1744 deed for the property was recorded in Orange County, Virginia even though Augusta County was created from Orange County in 1738. RM's automatic geocoding is not very useful for such situations. Similar situations exist in my database where I have exact coordinates (or as exact as my GPS device) for many different burials in the same cemetery. Even entering all the coordinates manually into RM, I would have to create a separate place  or a separate place detail for each burial.

 

My solution for these problems is to enter my exact GPS data into fact notes in RM so the data will print in narrative reports, but I create my maps with Google Maps from outside of RM.

 

Jerry