With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool.

The output polygon will follow the cell edges of the raster.

I'd like to create a polygon which follows the centres of the raster's edge cells.

Any idea how to do this?

I'm agnostic as to whether it uses arcgis, postgis, python, C, whatever...

The input can be an Esri 'Raster Dataset' or any gdal-supported format...

  • Using a negative buffer of half your raster cell size on the resulting polygons should get you pretty close.
    – Martin
    Sep 11 '14 at 10:18
  • Check from the lower right corner if output polygon follows the outmost edges of pixels or the top-left corners of pixels. Top-left is the tiepoint in GeoTiff's pixel is point model.
    – user30184
    Sep 11 '14 at 11:29

Some Arc options.

1) As Martin states above with a negative buffer (close).

2) Convert to points and use Feature Outline Masks or another convex hull tool (Info license).

3) Shift a copy of the raster by half the cell size in the x,y direction then convert.

4) Spatial Ecology has an option of doing 2 without Info license.

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