arcgis-10.0arcgis-desktopproximity
I am using ArcGIS 10, and trying to do the following:
I have a layer file of points (industrial facilities), and I would like to calculate the distance from each point to the nearest "eastern" polygon (U.S. state). I know there are tools for calculating distances from points to polygons, but I don't know how (or, if you can) specify direction of the polygon.
Any advice?
I don't believe there's a single command to do this, but we can still accomplish it expediently. The idea is that the distance to the nearest different cell equals the distance to the nearest location whose immediate neighborhood contains more than one cell type.
Well, this is not quite true, but it's close: you might want to add approximately one cell width to such a distance. If you can live with such an approximation, here's the workflow:
Compute a focal variety grid using as small a neighborhood as possible, which would be a 2 by 2 square neighborhood.
Nullify all locations with a focal variety of 1 or less: these are the "inside" cells.
Compute the Euclidean distance grid to all remaining cells: these are the distances to locations along boundaries.
(Optional) Add the cellsize to the distance grid.
Extract the values at any points you choose.
To illustrate, here is a small piece of a grid colored by cell type. The black areas are the cells with focal varieties of 2 or greater (computed at step 2):
A hillshaded Euclidean distance grid looks like this:
It reaches peaks (maximum values) within the centers of each patch of the original raster and decays to zero along the patch boundaries, still shown with black.
You would use the Near GP tool which:
Calculates distance and additional proximity information between the input features and the closest feature in another layer or feature class.
If you would like to calculate the distance from the centroid of every polygon (there are many variations on how a centroid could be defined - center of gravity or geometric center), you would need to create first those points (either using Feature To Point or other methods such as using Calculate Geometry).
Best Answer
Perhaps do a distance to all polygons (not sure if this returns a line or just a distance) then filter them by the angle of the line greater than 45 but less than 135 (everything easterlyish). Then order by distance and select the top 1... that is the logic, now you just need to code it.