Dividing A Polygon In Any Given Number Of Equal Areas (medial axis theory)

[Claus Bloch]

I have a concave polygon that i want to split in areas of equal size. I know that i has to be of way by medial axis as explained on http://www.khetarpal.org/polygon-splitting/

Does anyone have anyone have any experience with this in MapInfo?

Here is my polygon:

It is a road with parking areas along. The equal sized areas is for taking samples of the soil to analysis for different substances.

[rinus deurloo]

Maybe Subdivider.MBX (see attachment) can help you?

Rinus Deurloo

Amsterdam.

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M.C. Deurloo

i-mapping / MapGrove

Stuurboord 19

1316 VC Almere

The Netherlands

T: +31 87 7848742

M: + 31 6 23018952

E: m.c.d...@i-mapping.com

I: www.i-mapping.com  www.mapgrove.com

[Albert Tabino]

you can probably start by this: 

create the smallest grids you can(~5x5 feet)

[Claus Bloch]

Hi Rinus.

One problem is that i have an area of total 7229 Square meters, so i have some challenges with the Tool.

I managed to get some out of it:

But the slices are not equal in size. And the slices are not necessarily one unique object, but sometimes to objects with some distance apart. 

I have attached the tab. Maybe you can tell me what settings I Subdivision I need to us. The goal is to end up with 226 equally sized object / objects with roughly 32 m2 each.

/Claus  

Den onsdag den 3. august 2016 kl. 16.52.41 UTC+2 skrev rinus deurloo:

[Albert Tabino]

apologies...hit the send button...lol

try this:

  - create a gird table about (3x3 feet) and split your boundary with this table;

  - this would result into your boundary split into 3 x 3 feet grids;

  - determine the number of grids that would be distributed into the number of areas you need ( count of grids / number of areas) which would give you a decimal result.

  - the result ( which is grids per area) will give you a count of grids that would create areas  that would be more or less equal.. 

  - create a mapbasic routine (see figure) to capture the number of grids per area and that the routine should run in a direction along the centerline of your original boundary;

  - you may also set the routine to run in order according to a set of coordinates of your preference...

this should be doable, haven't tried it yet, but let us know if you get it to somewhere...enjoy!  

[Peter Horsbøll Møller]

If you create a grid, select the grids that are “within”, convert these to points and then use voronoi to split the polygon you get a split like this:

 

 

Peter Horsbøll Møller

EMEA Channel Enablement Specialist

Location Intelligence | MapInfo

 

M: +45 29 133 769

peter....@pb.com | @phorsbollmoller

pitneybowes.com/dk | mapinfo.com

[Albert Tabino]

Peter,

very nice results....cheers!

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M.C. Deurloo

i-mapping / MapGrove

Stuurboord 19

1316 VC Almere

The Netherlands

T: +31 87 7848742

M: + 31 6 23018952

E: m.c.d...@i-mapping.com

I: www.i-mapping.com  www.mapgrove.com

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[Peter Horsbøll Møller]

If you want to divide your area into a number of rectangles, have a look at the GridMaker tool that comes with MapInfo Pro.

 

Here’s an articles describing how to use it:

http://web.pb.com/mapinfopro-nov-2012/Toolbox-GridMaker

 

Peter Horsbøll Møller

Pitney Bowes

 

From: mapi...@googlegroups.com [mailto:mapi...@googlegroups.com] On Behalf Of Christina Fjorbak
Sent: 23. februar 2017 14:23
To: MapInfo-L <mapi...@googlegroups.com>
Subject: [MI-L] Re: Dividing A Polygon In Any Given Number Of Equal Areas (medial axis theory)

 

I'm kind of having the same problem, but i'm unfortunately not very experienced in mapinfo. 

 

I have  many stables i need divided into an equal sized squares (or whatever shape possible). 

I guess i need to specify my area (only the ground area where chickens are located) and then use the "subdivision" function, but i cannot make it work. Can anybody help me? Preferably with many details or even a step by step guide. 

Thanks!

 

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[Christina Fjorbak]

Thanks - i'll try!  

Right now i only have a picture of the stables (PNG files). How can i change them so i can use them in mapinfo?

Since i am not using coordinates, i have a problem every time mapinfo wants coordinates as well

[Christina Fjorbak]

I need a picture similar to the one Claus got. 

I use "Mapinfo professional" - can i go it with this or do i need to download the other program? 

Den torsdag den 23. februar 2017 kl. 14.44.21 UTC+1 skrev Peter Horsbøll Møller:

[Peter Horsbøll Møller]

You can use the images directly in MapInfo Pro.

When opening the image, you can either show it or register it.

 

If you go with the first option, the image will be shown in a map using a Non Earth coordinate system and therefor it will not be related to anything.

 

If you go with the second option, you’ll need to pin point orientation points in the image and find the matching point in a map.

When you have created at least four of these, MapInfo Pro will be able to orientate your image.

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[David Sherrod]

Christina,

To follow upon Peter's suggestion, you could make a simple map of your chicken pen.  As an example, see the attached image, which is a crude rendition along the theme of your overhead photo.  You need control points on your map so that GIS can add spatial data. In my map, I chose your pen edges where the struts come down along the sidewall.  You'll need a tape measure (on mine the distance was guessed). Then establish four corners. You can see the coordinate pairs (x, y) on my map.

Open your map in Mapinfo Pro, as raster (it will be a jpeg or tif or something like that, yes?). When Pro asks if you wish to register it, say yes. Your map will appear in the registration window.  FIRST, pick your projection, which would likely be nonearth-meters (my map would; yours might be in inches or feet or something else). PICK YOUR PROJECTION FIRST.   THEN establish your first point and assign it X, Y.    NEXT, hit the button for Add A Point, drop your mark there, and assign coordinate value to that point.  Complete the task for all four of your corners, each time hitting the button for Add a Point before placing the point.  Your task is simple, so four points will be sufficient. (I doubt you or the chickens will need greater precision or accuracy.)

Et Voila.  If done correctly, you'll end up with a geospatial map.  You can measure the area of the pen floor.  You can divide it into equal areas and even get the square meters of each area.  You could even ask MapInfo to calculate the average number of chickens per square meter.

[Christina Fjorbak]

I have made a polygon and used the Subdivider package this way:

Draw polygone> safe: Map> save cosmetic objects> New>

 

Open “subdivider” > click on folder > open polygone > mesh of equal area polygons > choose dimensions  (w*H) > (do not check of the two lower options) OK > Dice region  

But after trying it the first time it worked fine but now i cannot make it work. I get out squares as i want but they are not equal size. I tried the other functions as well but non of them seems to make equal squares in my polygon. 
Can anybody solve my problem?

PS thank you all for your help. Dave i could try your solution but then i need to make paint drawings of all stables, instead of drawing polygons in mapinfo? otherwise i will not have it as a raster file. Also, what do you mean with "tape meassure"? I don't really have any more informations than you do, having this picture. I know the lenght of the stable and the objects inside, but because of the video data, it is not really that usefull.

Thanks!