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I have a county polygon and a grid containing 1M cells that I want to overlay inside of the polygon. I have tried using the clip feature to cut the grid in the shape of the polygon. I continually get an NOT RESPONDING message after it seems to freeze on step 3 of 16.

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Hi Patrick, what version of ArcMap are you using? –  djq Aug 9 '11 at 19:25
    
I am using ArcMap 9.3 –  PatrickW Aug 9 '11 at 20:06
    
Have you tried clipping the same grid using a smaller polygon? If that works, then try a few intermediate size polygons as your clip layer to see if (and when) system resource issues appear to be kicking in. Also, is your grid 1 metre cells or 1 million cells? It would be useful to know how big that dataset is, and how many vertices in your clipping polygon. –  PolyGeo Aug 9 '11 at 22:36
    
@Patrick, are you wanting to clip the grid to calculate something or just for cartographic purposes? –  artwork21 Aug 9 '11 at 23:35
    
@PolyGeo The grid cell size is 1 meter and the total number of cells is around 350,000. The polygon is roughly 1/4 of the whole grid. Ultimately, I want to have the grid cell in the shape of the polygon so I can create centroids in each cell and give them a X,Y value. –  PatrickW Aug 10 '11 at 21:24
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2 Answers 2

Oh my. It is not freezing, you have 1million polygons and it is testing one by one! Normally, I would write a simple custom script to make it more eficient or do it in PostGIS. A faster way ia to grab the outer polygon ring as a polyline and only clip the grids that intersect that one, the features inside will stay the same and the features outside will be ommitted. Or you can just wait until it finishes :)

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I would suggest using the Polygon to Raster tool with a 1 meter cell size using your study area as input, then using the Raster to Point tool to arrive at points spaced one meter apart within your study area.

It should avoid the relatively expensive clip operation, however if your study area is large or with complex geometry, it might take a while to create the initial raster. I just performed this on a basic polygon which created 19,020 points (19,020m2) and it took a total of about 30 seconds to perform both steps - for what that's worth.

Edit to add: I tried this on a much larger polygon (6708490978.49684 m^2) and it took 12 minutes to create the raster (in a VM). However, the Raster to Points operation failed after ~9min because it exceeded the 2GB filesize limit of shapefiles. I'm about to try again using a geodatabase output. It doesn't seem like it will lead to an out of memory error either way, though.

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