MnGCA Home MnGCA
Minnesota Geocaching Association
 
 FAQFAQ   SearchSearch   User listUser list   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

GIS
Goto page 1, 2  Next
 
Post new topic   Reply to topic    MnGCA Forum Index -> Tech Talk
View previous topic :: View next topic  
Author Message
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 11:39 am    Post subject: GIS Reply with quote

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.
Back to top
View user's profile Send private message
Pear Head
Past MnGCA President


Joined: 04 Apr 2004

Posts: 5676
Location: north of Duluth

PostPosted: Fri Apr 27, 2007 11:47 am    Post subject: Re: GIS Reply with quote

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?
_________________
Hmm...
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 12:00 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message
pfalstad
Geocacher


Joined: 02 Feb 2006

Posts: 1007
Location: Edina

PostPosted: Fri Apr 27, 2007 12:23 pm    Post subject: Reply with quote

http://local.wasp.uwa.edu.au/~pbourke/geometry/insidepoly/

solution 1 looks good..
Back to top
View user's profile Send private message Visit poster's website
pfalstad
Geocacher


Joined: 02 Feb 2006

Posts: 1007
Location: Edina

PostPosted: Fri Apr 27, 2007 12:25 pm    Post subject: Reply with quote

What is this for? I know fidian has written something like this already.
Back to top
View user's profile Send private message Visit poster's website
ghost640
Geocacher


Joined: 03 Nov 2006

Posts: 270
Location: Independence, north of Twig

PostPosted: Fri Apr 27, 2007 1:04 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message
Pear Head
Past MnGCA President


Joined: 04 Apr 2004

Posts: 5676
Location: north of Duluth

PostPosted: Fri Apr 27, 2007 1:19 pm    Post subject: Reply with quote

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.
_________________
Hmm...
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger
Marsha and Silent Bob
Past MnGCA President


Joined: 02 Sep 2003

Posts: 6261

PostPosted: Fri Apr 27, 2007 3:46 pm    Post subject: Reply with quote

merkman,

Contact the guy that does itsnotaboutthenumbers.com (or apparently fidian based on pfalstad's post).
_________________
Sad state of affairs.
Back to top
View user's profile Send private message
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 4:51 pm    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 4:53 pm    Post subject: Reply with quote

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!!!
Back to top
View user's profile Send private message
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 4:58 pm    Post subject: Reply with quote

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?
Back to top
View user's profile Send private message
pfalstad
Geocacher


Joined: 02 Feb 2006

Posts: 1007
Location: Edina

PostPosted: Fri Apr 27, 2007 5:49 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message Visit poster's website
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 6:10 pm    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
pfalstad
Geocacher


Joined: 02 Feb 2006

Posts: 1007
Location: Edina

PostPosted: Fri Apr 27, 2007 6:41 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message Visit poster's website
merkman
Past MnGCA Board


Joined: 03 Jun 2006

Posts: 2032

PostPosted: Fri Apr 27, 2007 7:15 pm    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    MnGCA Forum Index -> Tech Talk All times are GMT - 6 Hours
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2002 phpBB Group
Geocaching Cache Icons, Copyright 2009, Groundspeak Inc. All rights reserved. Used with Permission.