topic Re: Converting Raster/Map to Lower Resolution in Data Management Questions

Converting Raster/Map to Lower Resolution

AshleyBerg — Tue, 21 Jun 2011 23:09:58 GMT

Note: I am new to GIS and using ArcMap, so I know very little.

I recently used ArcMap to convert a Raster dataset to a lower resolution, from a cell size of about 0.07 to 0.5. I then converted this Raster to an ASCII file (because I wanted it to be a 0.5x0.5 degree grid for input into a model). Does anyone know the exact technique that ArcMap uses to convert a dataset/map from higher resolution to lower resolution? The resulting lower resolution map looks great compared to the high res just from eyeballing it, but I'd like to know how the program does it, if anybody could enlighten me.

Thank you!

Re: Converting Raster/Map to Lower Resolution

TimothyHales — Wed, 22 Jun 2011 11:45:09 GMT

A change in cell size like that will cause you to loose some of your data. The process of using the Resample tool will determine the centroid of the cells for the output raster. Then based upon the location of the output centroid it will determine the value by looking at the cell centroids of the input raster using the chosen resampling technique. Here are the techniques you can use:

NEAREST �??Nearest neighbor assignment
BILINEAR �??Bilinear interpolation
CUBIC �??Cubic convolution
MAJORITY �??Majority resampling

You can read more on the techniques and see examples in the Cell size and resampling in analysis help document.

Re: Converting Raster/Map to Lower Resolution

AshleyBerg — Wed, 22 Jun 2011 17:37:38 GMT

Thanks for the help!

I have one more question. If I use the Export Raster Data option, and change the cell size of the output raster to a larger one this way, is this essentially the same as using the Resample tool?