I have an assignment to create a simplified depth scheme. The calculation has to be done for a large area automatically.

There are depth points every 0.5 meters (marked black in the picture). By using “point to raster” function I can generate a raster layer with defined size cells (e.g. 4x4 m) and also request to calculate lowest (shallowest) values for each cell.

Then I can create points layer from the raster generated before, which results is a layer of depth every 4 m (points in red) with lowest values. However the points are generated in the center of the cell. They do not represent the actual place within the cell with lowest value (yellow points).

How can I get the points with lowest value and exact location for each cell?

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  • 2
    If you don't mind me asking, what is the application of this? I don't see why the 4m raster matters when you already have the values in the points. Do you really need to average across all potential configurations of 81 point neighborhoods? – jbchurchill Sep 16 '16 at 13:15
  • I have raw data with points every 0.5 meters. Earlier it was enough to show just minimum depth's values in grid of 4x4 meters. But now our client also wants to see a map with exact places of minimum depths. – Viaceslav Jurkin Sep 19 '16 at 8:04

You could use "Generate Fishnet" to create 4x4 polygons, then do a spatial join to get the stats on points within each polygon. Then select where value of the point = min within that fishnet polygon.

Or use "Block Statistics" (neighbourhood = rectangle and statistics = Minimum) and "extract values to points" to get the block minimum value (I.e the minimum value in a 4x4 cell) attributes in the point layer. Then query your point layer and when point value = block min (extracted), that is the point you're looking for.

| improve this answer | |
  • Please add more info about what and how to use – Midavalo Sep 16 '16 at 20:54
  • Jae, second method worked perfectly. But using first method I don't understand how to do last step - "select where value of the point = min within that fishnet polygon." – Viaceslav Jurkin Sep 19 '16 at 7:13

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