How do I properly set the cell size that I want when converting polygons to raster files?

Also on the raster file Layer Properties what exactly does the Cell Size indicate, as it doesn't seem to correlate when I measure a cell?

Here is the background to my question.

I'm converting a shapefile that represents radio signal strength to a raster file. The shapefile is made up of polygons that each represent average signal strength inside that polygon. Each polygon is 3 x 3 arc-seconds with a single value to represent signal strength. In my area 3 x 3 arc-seconds equates to about a 76.8 meter x 92.6 meter rectangle. When I convert to raster I would like to have similar resolution, so I was hoping that when I converted the shapefile each cell could be approximately the same size or smaller than the 76.8 meter x 92.6 meter rectangle polygons.

Using the "polygon to raster tool" Figure 1, it automatically sets the cell size to .0052. What units is that in?

Figure 1

When I look at the new raster file, Figure 2, it clearly states that the cell size is .0052 x .0052 but I see nothing that specifies what units .0052 represents.

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Measuring the individual cells however, I get measurements that don't seem to correspond to .0052 of any units I've tried, Figure 3. Here using the pixel inspector I identified an individual cell and found it to be about 577.86 x 475.1 meter or 1,885.4 x 1,559.03 feet.

enter image description here

Just to be complete here are the Dataframe setting in Figure 4 showing that the units are in Feet.

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  • 1
    It's a long question.. I lost interest about halfway through. From what I did read you're confused about the cell size, you can specify an existing raster to match the cell size (don't forget environment SnapRaster as well) but if you use a numeric value it's always a square cell. If you want a 3x3 second cell project your input data into geographical (WGS84/Geographic should be good) then use a cell size of 0.000833333 (3 seconds as decimal degrees) then project the raster to your desired projected coordinate system (or not, it should still be mostly usable with project on the fly). – Michael Stimson Sep 6 '18 at 23:55
  • Yeah, maybe I added too much information. But the main point is I'm trying to figure out how to specify cell size. My conversion specifies cell size of .0052 but I have no idea what that means. The cells it does render are about 577.86 x 475.1 meters ( 1,885.4 x 1,559.03 feet). So what does .0052 mean?? – Frank Sep 7 '18 at 4:49
  • 1
    0.0052 would be degrees (geographic units), perhaps your data or data frame is geographic and its using that as a measure, as for where ArcGIS gets the suggested default number 0.0052 from, it's a division of the extent of your dataset (wide or tall) by a constant number of pixels. Try changing 0.0052 to 0.000833333 to get cells approximately what you're after. What coordinate reference system is the derived raster in? I would hazard a guess and suggest that your output raster is in a geographic CRS which is why you're seeing rectangular cells. – Michael Stimson Sep 7 '18 at 5:11
  • Thanks! That didn't solve all my problems, but at least now I know what I'm working with. – Frank Sep 7 '18 at 5:42

Using the "polygon to raster tool" Figure 1, it automatically sets the cell size to .0052. What units is that in?

It is in decimal degrees. One degree of latitude is equivalent to approximately 111,111 m.
(see for example, whuber's answer in Algorithm for offsetting a latitude/longitude by some amount of meters).

The current pixel size of your raster in north-south direction is equivalent to:

0.0052 degrees x 111,111 meters/degree = 577.8 meters

So, if you want the pixel to be 92.6 meters in north-south direction, then set the resolution to:

92.6 meters / (111,111 meters/degree) = 0.0008334 degrees

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