Does square root of cell size = cell area?

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07-21-2014 10:23 AM
ShawnGazzano
New Contributor II

Considering this statement, "suppose we use an output cell size of 0.5 kilometers, and we see that one cell receives a value of 16 crimes per square kilometer.  Since the area of the cell is 0.25 square kilometers (0.5 km * 0.5 km = 0.25 km2), we can multiply the density by the area to get an expected count of 4 crimes (16 crimes/km2 * 0.25 km2 = 4 crimes)...."

 

....does the square root of Cell Size (Kernel Density tool) equal the area of each cell (I'm using square miles for Area Units)?

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5 Replies
DanPatterson_Retired
MVP Emeritus

Cell size does not describe the area of the cell but ... for square cells ... the length of its sides, hence, cell area = cell size squared

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ShawnGazzano
New Contributor II

Where do I find the length of a cell's sides?

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DanPatterson_Retired
MVP Emeritus

the cell size is the length of the side of cell...it is an unfortunately use of the term...but you are stuck with it

More information can be obtained in the help files by searching "cell size"...for example

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

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ShawnGazzano
New Contributor II

Ok.  I think I'm reading too much into this, and overlooking the simplicity.

To clarify, if I'm running the kernel density tool, and using 100 has my cell size and square miles as area map units, then the cell area is 10000 square miles? (per your first reply, cell area = cell size squared)

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DanPatterson_Retired
MVP Emeritus

One last try...I doubt that your cell size is 100 miles wide, hence, your estimate of area is incorrect.  Examine the units of your raster...depending upon the source, I suspect that they are either in meters or feet...this information can be found in arccatalog amongst other places.  The units that you set the data frame in are not relevant and I would strongly suggest setting them to anything other than native units.  So when you find out what units the raster is in, the area will either be 10,000 square meters or 10,000 square feet...both of which can be converted to square miles using an online calculator.  Good luck again

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