Splitting an irregular polygon into smaller polygons of a size

[Thiru_P]

Hi fellow members,

I would like to split an irregular polygon into smaller uniform sized polygons i.e dividing a land parcel into many 1sqkm rectangular polygons and leaving the residual polygon as it is.

Is there a script or function that can accomplish this task. I only have ArcGIS Basic and do not have a Parcel Editor extension or anything.

Thanks in advance for pointing me in the right direction.

[AnthonyCheesman1]

Gday

Yes there is a way. I would use the 'fishnet' tool to make the grid.

Can't immediately help with the coding, but I would use the following process.

# determine extent of your irregular polygon
# create fishnet within that extent with your 1km parameters
# clip fishnet polygon to the extent of your irregular polygon
# union the clipped fishnet and your irregular polygon
# clean up any unwanted fields

Good luck!

[ChristopherThompson]

Using the intersect tool will accomplish, in one step, the same result as:

# clip fishnet polygon to the extent of your irregular polygon
# union the clipped fishnet and your irregular polygon

I'm concerned about the 'uniform sized polygons' requirement and not sure what you mean about leaving the 'residual polygon' as is... Do you mean, anything that doesn't end up as a 1km square should be a single polygon that rings those regularly sized/shaped portions?

If so, then you have to add to the steps already given a process to calculate area, then select everything that has an area < 1km^2 and then merge those into a single polygon.

And hopefully these are not overlapping polygons.  Regardless, depending on how 'clean' the topology is for your polygon data you may want to wrap all this up in a cursor so that you can process the features one by one.  And then of course you have to ask yourself if the fishnet you create is a grid to overlay the dataset as whole, or do you want create that for each feature you have to do this for.  Depending on how these data will be used, that could be a significant issue I think.

[ChrisSnyder]

Also, look into the Dice tool (new in v10.0): http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//001700000037000000.

It will split a polygon into smaller polygons based on vertex counts...  but you will not have any direct control on their size. As a post process, you could append polygons that were too small with their larger neighbors. The logic of that may be more work than you are willing to put into it though...

[Thiru_P]

Thanks Anthony, looks like I could use your logic.

Christopher, the bigger ones are non-overlapping polygons. If the residual is one big polygon that doesn't make the 1 km by 1 km size, then it is fine. If there are many fragments that could make a combined total of more than a 1 km by 1 km grid I would like to have it split it subsequently.

Thanks, Chris. The dice tool works only with ArcINFO. We don't have it.

I wish I had the ArcEditor licens that has the Parcel Fabric tool..**sigh**

Gday

Yes there is a way. I would use the 'fishnet' tool to make the grid.

Can't immediately help with the coding, but I would use the following process.

# determine extent of your irregular polygon
# create fishnet within that extent with your 1km parameters
# clip fishnet polygon to the extent of your irregular polygon
# union the clipped fishnet and your irregular polygon
# clean up any unwanted fields

Good luck!