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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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 Posted: Fri Apr 27, 2007 11:39 am Post subject: GIS |
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If this makes sense to you please e-mail me.
You'll need to find someone to do some programming for you. It's pretty straightforward. County outlines are available at http://deli.dnr.state.mn.us/metadata.html?id=L220000030201 Your programmer needs to run a point-in-polygon routine and return the polygon (aka county) name for each point. |
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Pear Head
Past MnGCA President
Joined: 04 Apr 2004
Posts: 5600
Location: north of Duluth
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| Posted: Fri Apr 27, 2007 11:47 am Post subject: Re: GIS |
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| merkman wrote: |
If this makes sense to you please e-mail me.
You'll need to find someone to do some programming for you. It's pretty straightforward. County outlines are available at http://deli.dnr.state.mn.us/metadata.html?id=L220000030201 Your programmer needs to run a point-in-polygon routine and return the polygon (aka county) name for each point. |
The county outlines are simply a collection of polygons, each of which makes up the borders of a county.
A point-in-polygon routine will determine if the point (ie. coordinates) falls within the polygon definition for that county (ie. does it fall within the borders for that county).
I just saw a short discussion about this on an unrelated list I was on. There is a fairly simple routine to handle it that had something to do with 'drawing' a line from your point to a far away point (such as the north pole) and seeing how many times this imaginary line crossed the polygon borders. I've never seen the actual code to do it though.
I've never tried this as I'm not familiar with shapefiles, which is what I'm assuming the polygons are given in (I didn't look at them). I would think that you could probably find free code out there that will do this though.
That help?
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 12:00 pm Post subject: |
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I guess I don't even know what software to start with.
It would be cool to find someone who has access to all the "big boys toys" to whip something like this up for me. |
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pfalstad
Geocacher
Joined: 02 Feb 2006
Posts: 967
Location: Edina
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pfalstad
Geocacher
Joined: 02 Feb 2006
Posts: 967
Location: Edina
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| Posted: Fri Apr 27, 2007 12:25 pm Post subject: |
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| What is this for? I know fidian has written something like this already. |
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ghost640
Geocacher
Joined: 03 Nov 2006
Posts: 268
Location: Independence, north of Twig
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| Posted: Fri Apr 27, 2007 1:04 pm Post subject: |
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| Shapefiles are GIS files used by ESRI products - ArcGIS (techy-programmer-type required), ArcView (sort of user friendly), and ArcExplorer (a free viewer at www.esri.com). You'd need ArcView or higher to do the point-in-polygon operation. |
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Pear Head
Past MnGCA President
Joined: 04 Apr 2004
Posts: 5600
Location: north of Duluth
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| Posted: Fri Apr 27, 2007 1:19 pm Post subject: |
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| ghost640 wrote: |
| Shapefiles are GIS files used by ESRI products - ArcGIS (techy-programmer-type required), ArcView (sort of user friendly), and ArcExplorer (a free viewer at www.esri.com). You'd need ArcView or higher to do the point-in-polygon operation. |
I'm guessing here that merkman wants to determine points in a county on the fly for some application. Although I don't have experience with ESRI products, I'm guessing that it may be hard to code them into software. Maybe merkman can expand on the application?
You can also manipulate a shapefile without the software - it's not a proprietary format. I have other software that does it although I've never looked at the code that does it.
Finding other code would be the way to go.
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Marsha and Silent Bob
Past MnGCA President
Joined: 02 Sep 2003
Posts: 6261
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| Posted: Fri Apr 27, 2007 3:46 pm Post subject: |
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merkman,
Contact the guy that does itsnotaboutthenumbers.com (or apparently fidian based on pfalstad's post).
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Sad state of affairs. |
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 4:51 pm Post subject: |
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| Marsha and Silent Bob wrote: |
merkman,
Contact the guy that does itsnotaboutthenumbers.com (or apparently fidian based on pfalstad's post). |
Great idea I tried it but he didn't respond.
merk |
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 4:53 pm Post subject: |
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| pfalstad wrote: |
http://local.wasp.uwa.edu.au/~pbourke/geometry/insidepoly/
solution 1 looks good.. |
I need to look at this. Indepth.
Thanks for the link!!! |
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 4:58 pm Post subject: |
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| pfalstad wrote: |
| What is this for? I know fidian has written something like this already. |
It is to find out what Minnesota County a certain point in Minnesota falls into. Not on the fly but I have a large batch of points (just under 5000) I would like to process. ie a "one time batch"
Maybe someone has done this before? |
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pfalstad
Geocacher
Joined: 02 Feb 2006
Posts: 967
Location: Edina
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| Posted: Fri Apr 27, 2007 5:49 pm Post subject: |
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| merkman wrote: |
| pfalstad wrote: |
| What is this for? I know fidian has written something like this already. |
It is to find out what Minnesota County a certain point in Minnesota falls into. Not on the fly but I have a large batch of points (just under 5000) I would like to process. ie a "one time batch" |
Caches? If so, I would use itsnotaboutthenumbers.com or http://rumkin.com/tools/gps/analyze.php . If not, then I would generate a gpx file from the points and use the rumkin site. |
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 6:10 pm Post subject: |
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| pfalstad wrote: |
| Caches? If so, I would use itsnotaboutthenumbers.com or http://rumkin.com/tools/gps/analyze.php . If not, then I would generate a gpx file from the points and use the rumkin site. |
I don't have just under 5000 finds |
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pfalstad
Geocacher
Joined: 02 Feb 2006
Posts: 967
Location: Edina
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| Posted: Fri Apr 27, 2007 6:41 pm Post subject: |
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| merkman wrote: |
| pfalstad wrote: |
| Caches? If so, I would use itsnotaboutthenumbers.com or http://rumkin.com/tools/gps/analyze.php . If not, then I would generate a gpx file from the points and use the rumkin site. |
I don't have just under 5000 finds |
Doesn't matter, generate a gpx file from the points, zip it and feed it in there anyway. Add ?debug=1 to the end of the URL if you need county info for each point, instead of just total # points for each county. Not sure it'll work, but it would save a ton of time if it did. |
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merkman
Past MnGCA Board
Joined: 03 Jun 2006
Posts: 2032
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| Posted: Fri Apr 27, 2007 7:15 pm Post subject: |
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| pfalstad wrote: |
| merkman wrote: |
| pfalstad wrote: |
| Caches? If so, I would use itsnotaboutthenumbers.com or http://rumkin.com/tools/gps/analyze.php . If not, then I would generate a gpx file from the points and use the rumkin site. |
I don't have just under 5000 finds |
Doesn't matter, generate a gpx file from the points, zip it and feed it in there anyway. Add ?debug=1 to the end of the URL if you need county info for each point, instead of just total # points for each county. Not sure it'll work, but it would save a ton of time if it did. |
I will give it a shot. |
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