Limiting extent of Kriging to Polygon

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08-01-2012 08:16 AM
DeanMorgan
New Contributor
Hi,

I am hoping this is straight-forward, fairly new to GA.

I want to limit the extent of my kriged surface to the boundaries of my polygon. The problem is, the polygon is an Archipelago, thus when I choose limit extent to 'polygon name', it merely limits the kriged surface to the far reaches of the Archipelago in a rectangular shape. I only want to keep the kriged surface covering the islands (i.e. land) not the sea. Is this possible?

Any guidance would be greatly appreciated. Thank you in advance.
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8 Replies
SteveLynch
Esri Regular Contributor
Dean

A Geostatistical layer cannot be masked per se. You can, however, clip the data frame. (in ArcMap, right click the Layers in the TOC and choose Data Frame Properties and supply a clipping polygon).

In 10.1 you can supply a MASK via the environment when using the GALayerToGrid tool. Pre 10.1, you can use Spatial Analyst's Plus tool to add zero to your exported raster and supply a MASK in the environment.

Steve
DeanMorgan
New Contributor
Steve,

Thank you very much. Via the Data Frame Properties I supplied the country outline as the mask, or shape to clip to. It gave exactly the coverage I wanted.

BUT, having applied this, ArcMap 10 became inoperable, in that it became unbelievably sluggish, and so had to force close. This happened each time I tried. My system was flying through other programs which were open, suggesting it is more than capable of operating. Does this task require large amounts of memory and processing??

..............just tried from scratch assuming I had too many layers in the TOC. Just with one kriged layer the program literally becomes unresponsive! How can this be so?? The worst part is, I saved my workspace with all my previous work on, with this clipped data frame, now I cannot even access it! Everytime I click anywhere on the screen the program becomes unresponsive!
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DeanMorgan
New Contributor
Wow, literally took 20 minutes to open ArcMap again with this clipped data frame, as opposed to 5 seconds before. Is there something I am missing, this is certainly not the intended or desired performance of this tool I know. Any help hugely appreciated at this time....

...The program finally unfroze, changed to no clipping, and everything runs smoothly again. Not a tool I will use again in a hurry! But I still need a kriged surface limited to land areas of my polygon.

I previously tried the raster option as you stated Steve, but my classes (in this case, precipitation) were vastly altered....

How can I retain the classes when exporting to raster?? The kriged surface prior to export is fantastic, as are the true values of the rainfall data, I just want to limit the display of this surface to the outline of my polygon, with no preference to how I get to there!

Is there anyway I could invert the colours of my polygon. Perhaps having the areas around the land coloured white to isolate the kriged surface?? [ATTACH=CONFIG]16687[/ATTACH]


This is what I want to achieve [ATTACH=CONFIG]16688[/ATTACH], but this was using the data frame cliping, and ArcMap simply fails to operate, probably due to the intricacy of the polygon used to clip
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DeanMorgan
New Contributor
This is want I want to achieve [ATTACH=CONFIG]16689[/ATTACH]

But, this is via data frame clipping, and I now assume that due to the intricacy of the polygon shape, ArcMap simply fails to operate, essentially crashing.
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EricKrause
Esri Regular Contributor
I've experienced this slow-down when doing data frame clipping.  The issue for me was that the polygon had way too many vertices. If you use the Simplify Polygon tool on the clipping polygon, it should start working quickly again.
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DeanMorgan
New Contributor
Bingo! Thank you Eric!
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SolanaFoo4
New Contributor III

Odd, I am seeing tremendous slow down kriging with either data frame clipping, or setting the environment variable for extent or mask to my polygon layer.  My polygon was quickly hand-drawn and does not have a lot of vertices.  Process takes less than a minute without any of those restrictions, and going on over an hour with them in both catalog and arcmap.

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SteveLynch
Esri Regular Contributor

Solana

Please tell me;

  • what version of ArcGIS
  • which geoprocessing tools are you using
  • do all the data have the same spatial reference

Thanks

-Steve

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