Setting raster resolution in meters when working in a Geographic Coordinate System

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09-26-2014 02:27 AM
CharlyParra
New Contributor II

Hi, I work in WGS 84 (Geographic Coordinate System) in ArcGIS 10.1. I need to create a raster specifying its cell size in meters, and output it in WGS84.

 

Is it a good solution (towards a less shape/area distortion of the final result) to proceed in this way?: Create the raster from the shape which is in a Geographic CRS (WGS84), having set before the CRS of the Data Frame to a projected one (WGS84 UTM) in order to be able to give cell size in meters, which be a small value in relation with the actual required resolution in order to get accurate result when the expected resampling happens; then, once the raster is in a projected CRS, reproject it to WGS84 (the resampling is expected that involves a low shape/área distortion)?

 

IMPORTANT for this implementation to be practical: In the last step (reproject the raster to WGS84), when specifying the Cell size of the resulting projected raster, the units of the default value that appears are decimal degrees. Are this value coincident with the Cell size in meters of the raster from which I am projecting to WGS 84?

 

Another doubt to solve: Which would be the proper projected coordinate system through the raster would pass, better than WGS84 UTM? A equal area one? an equal distance one? Or would UTM (which is a equal shape one) be the best?

 

Tahnk you in advance for any help given.

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2 Replies
DanPatterson_Retired
MVP Esteemed Contributor

I would not try to mix geographic and projected coordinates in your analysis.  If you intend to work with geographic coordinates you will have to resolve the fact that your cell width in planar units is decreasing as you head poleward.  If your intent is to work ultimately in projected coordinates, use that data prior to rasterizing

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CharlyParra
New Contributor II

Dan, Thanks. Anyway, I need to handle both planar measurements (for cell size of the raster) and Geographic Coordinate System (for outputting  results).

So, I was trying to know the suitability of the proposed procedure, even assuming that it wouldn't be absolutely perfect. I would need to find the less imperfect method for this purpose.

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